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Regeneration of Assembled, Molecular-Motor-Based Bionanodevices
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  • Mohammad A. Rahman
    Mohammad A. Rahman
    Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden, 39182
    NanoLund, Lund University, Lund, Sweden, 22100
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    Orcidhttp://orcid.org/0000-0002-2797-2294
  • Cordula Reuther
    Cordula Reuther
    B CUBE − Center for Molecular Bioengineering, Technische Universität Dresden, Sachsen, Germany, 01062
    Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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  • Frida W. Lindberg
    Frida W. Lindberg
    Division of Solid State Physics  and  NanoLund, Lund University, Lund, Sweden, 22100
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    Orcidhttp://orcid.org/0000-0001-5617-6337
  • Martina Mengoni
    Martina Mengoni
    B CUBE − Center for Molecular Bioengineering, Technische Universität Dresden, Sachsen, Germany, 01062
    Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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  • Aseem Salhotra
    Aseem Salhotra
    Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden, 39182
    NanoLund, Lund University, Lund, Sweden, 22100
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  • Georg Heldt
    Georg Heldt
    Fraunhofer Institute for Electronic Nano Systems, Chemnitz, Germany 09126
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  • Heiner Linke
    Heiner Linke
    Division of Solid State Physics  and  NanoLund, Lund University, Lund, Sweden, 22100
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  • Stefan Diez*
    Stefan Diez
    B CUBE − Center for Molecular Bioengineering, Technische Universität Dresden, Sachsen, Germany, 01062
    Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
    *Tel: +4935146343010. Fax: +49351463 40322. E-mail: [email protected]
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    Orcidhttp://orcid.org/0000-0002-0750-8515
  • Alf Månsson*
    Alf Månsson
    Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden, 39182
    NanoLund, Lund University, Lund, Sweden, 22100
    *Tel: +46708866243. Fax: +46480446262./ E-mail: [email protected]
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    Orcidhttp://orcid.org/0000-0002-5889-7792
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Nano Letters

Cite this: Nano Lett. 2019, 19, 10, 7155–7163
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https://doi.org/10.1021/acs.nanolett.9b02738
Published September 5, 2019

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Abstract

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The guided gliding of cytoskeletal filaments, driven by biomolecular motors on nano/microstructured chips, enables novel applications in biosensing and biocomputation. However, expensive and time-consuming chip production hampers the developments. It is therefore important to establish protocols to regenerate the chips, preferably without the need to dismantle the assembled microfluidic devices which contain the structured chips. We here describe a novel method toward this end. Specifically, we use the small, nonselective proteolytic enzyme, proteinase K to cleave all surface-adsorbed proteins, including myosin and kinesin motors. Subsequently, we apply a detergent (5% SDS or 0.05% Triton X100) to remove the protein remnants. After this procedure, fresh motor proteins and filaments can be added for new experiments. Both, silanized glass surfaces for actin–myosin motility and pure glass surfaces for microtubule–kinesin motility were repeatedly regenerated using this approach. Moreover, we demonstrate the applicability of the method for the regeneration of nano/microstructured silicon-based chips with selectively functionalized areas for supporting or suppressing gliding motility for both motor systems. The results substantiate the versatility and a promising broad use of the method for regenerating a wide range of protein-based nano/microdevices.

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Protein adsorption to surfaces is a ubiquitous and extremely important phenomenon. (1−4) Whereas it may be unwanted in several instances, it has also been widely exploited in biotechnology as well as in fundamental biophysical and biochemical investigations. (5) For instance, antibodies, or other protein-based recognition molecules, are adsorbed to detector surfaces in biosensing (6−10) and proteomics (11,12) applications. In addition, fundamental functional studies often rely on surface adsorption of receptors and protein nanomachines. (13−15) One widely used assay of the latter type is the in vitro gliding motility assay. In this assay, (16) biomolecular motors isolated from cells are adsorbed onto a surface, enabling the propulsion of cytoskeletal filaments that can be observed by microscopy. Two commonly studied systems are actin filaments propelled by myosin motors (16−19) and microtubules propelled by kinesin (20) or dynein motors. (21) These motor systems are responsible for cell motility, muscle contraction, and intracellular cargo transport. Modified versions of the assay may also be applied to noncytoskeletal motors, such as processive DNA enzymes. (22) In vitro gliding motility assays have also enabled a variety of nanotechnological applications, for example, in nanoseparation and biosensing (6,23−30) and more recently, parallel biocomputation. (31) Many of these applications require nano/microstructured surfaces for physically and chemically confined filament transport along predefined paths, involving widely differing surface materials and chemistries. It is also expected that such devices will become increasingly complex in the future, for example, by integrating (opto)- electronic components for automated read-out of filament positions and velocities. (31)

The nano/microstructures used for molecular-motor-based devices are both expensive and time-consuming to produce. Furthermore, processes to fabricate them (such as electron beam lithography) consume a fair amount of energy. (32) It is therefore highly desirable to develop methods that enable the effective regeneration and reuse of these nano/microstructures. In such processes, all proteins that have deteriorated over time are ideally replaced by fresh, functional proteins without the need to disassemble the chips from their microfluidic environments. At the same time, it is important that the surface regeneration is achieved without destroying the nano/microstructures. Ideally, the process also preserves the motility-contrast between motility-supporting and motility-suppressing areas, which are often sustained by the use of different surface chemistries. (33−35)

In previous efforts to regenerate protein-coated surfaces, various approaches have been tested. These range from gentle methods, such as incubation with high-ionic-strength solutions (36) and detergents (37−39) or a combination of detergents and acids (39), (40) to harsher methods including highly concentrated acids, oxygen plasma, (41) or laser treatment. (42) Whereas the gentle methods often fail in effectively removing all aged proteins, harsher methods often alter the surface chemistry as well as the physical properties of the nano/microstructures and electronic components. Moreover, some of the procedures, such as oxygen plasma treatment, require disassembly of the devices.

We present here a novel method for regenerating molecular-motor-based nano/microdevices that keeps both the surface chemistry and surface topography intact and that does not require disassembly of the devices. We applied the described regeneration procedure to in vitro motility assays with both the actin–myosin and the microtubule–kinesin systems. Furthermore, we varied the substrates as well as the chemically and topographically structured surfaces. In the case of actin–myosin assays, we use the soluble myosin motor fragment heavy meromyosin (HMM), chymotryptically cleaved off from myosin. This is the most commonly used motor fragment in nanotechnological applications of actin–myosin as well as in most fundamental studies using the in vitro motility assay. Different surface chemistries were tested because the most optimal HMM-driven actin-motility is obtained on a distinct surface chemistry compared to kinesin-driven microtubule motility, investigated here by using kinesin-1. Likewise, the required surface chemistry for motility-suppression varies for the two motor systems. It was also essential to verify that the latter chemical properties are not altered by the regeneration procedure because motility-suppressing areas are central in functional devices. Importantly, using our approach, we find that repeated regeneration is possible for both motor systems, with maintained selectivity of motor function between different areas on a chip. The extension of the regeneration method to a range of nonmotor applications is discussed in view of the importance of protein adsorption in diverse fields.

To investigate and optimize different protocols for surface regeneration, we compared the performance of motor-driven filament gliding before and after surface treatment. Specifically, we adhered motor proteins to the surfaces, added fluorescently labeled filaments in the presence of the chemical energy molecule adenosine triphosphate (ATP) and recorded the gliding motility on a fluorescence microscope. Subsequently, for surface regeneration we aimed to clean the surface without device disassembly, by application of proteinase K and/or PMSF and/or detergents to the devices, including intermediate washing steps. After reapplication of fresh motors and filaments to the same device we recorded the resulting gliding motility.

In initial studies, using the actin–myosin system, we found that treatment with proteinase K or with different detergents alone only led to partial regeneration (Figures S1–S3, Table S1). Proteinase K treatment prevented surface binding of newly added actin filaments if no fresh HMM motors had been added after the treatment. In partial analogy, newly added microtubules exhibited only rare binding (with no motility), if no fresh kinesin motors had been added after the treatment. These findings suggest that functional motors are effectively digested by proteinase K. If fresh HMM motors were added after proteinase K treatment, however, there was motor-driven transport of subsequently added actin filaments albeit with lower velocity and increased filament lengths compared to our controls. The latter characteristics suggest a low density of functional motors, (43,44) likely due to protein remnants on the surface with inhibition of high-density binding of fresh HMM. This is consistent with results from Coomassie brilliant blue staining to assess the total protein, peptide, and amino acid surface binding. Such staining (Figure 1) reveals only limited removal of motor protein remnants following proteinase K treatment. Because we expected the remnants to be removed by detergents, (2) we cleaned the surfaces with detergent after proteinase K treatment. A subsequent Coomassie stain corroborated the idea that almost all protein remnants had now been removed (Figure 1). Also, the contact angle of water droplets after full regeneration of a trimethylchlorosilane derivatized surface was largely unchanged when measured on one control surface in three different locations (71.3 ± 1.5°; mean ± SD) compared to the preregeneration value (72.8 ± 2.0°). This supports the idea that the regeneration procedure preserves the key surface properties. In accordance with this idea, the motor propelled actin filament velocity, the fraction of motile filaments, and the average filament length all recovered to the initial control values after regeneration. Intermediate PMSF treatment (to terminate proteolysis; Figure 1) was of value by yielding higher relative gliding velocities after regeneration and was therefore included as a standard step in our optimized protocol.

Figure 1

Figure 1. Optimized method for regeneration of molecular-motor-based nano/microdevices. (a). After performing an in vitro motility assay (left panel), the main steps of the regeneration process (right panel) are (i) incubation with proteinase K (200 μg/mL; preactivated by Ca) for 1 h at 37 °C to digest the surface-adhered proteins, followed by (ii) incubation with PMSF (5 mM) for 5 min at room temperature (RT) to inactivate any remaining proteinase K, and (iii) incubation with SDS (5%) or Triton X100 (0.05%) for 5 min at room temperature to remove protein fragments from the surface. Afterward, fresh proteins can be added for new motility assays. Inset photos: Coomassie brilliant blue stain (0.1%) of the flow cell before addition of HMM or any other component (control), immediately after incubation with HMM at surface-saturating concentration (120 μg/mL) and after steps (i) and (iii) of the regeneration process. (b) Flow-cell opacity (average intensity measured from region of interest (ROI) in flow cell area subtracted by the average intensity in similar ROI on the glass outside the flow cell). Data from two experiments using Triton X100 (0.05%) as detergent (given ± pixel standard error of the mean) normalized to control value. See SI for details.

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More generally, using standard surface substrates, we found that the motile function (measured by gliding velocity, fraction of motile filaments, and filament lengths) after regeneration was fully restored compared to the control, both for actin–myosin on trimethylchlorosilane [TMCS] derivatized glass and SiO2 and for microtubule–kinesin on cleaned glass surfaces (Figure 2; Movies S1, S2, S3, and S4). With regard to their innate material properties, we here consider SiO2 and glass as equivalent substrates. (45)

Figure 2

Figure 2. Gliding motility assays before and after regeneration. (a,c) Fluorescence micrographs zooming in on five gliding actin filaments on an HMM-coated, TMCS-derivatized SiO2 surface before (a) and after (c) regeneration. The images show maximum projections (derived using ImageJ (46)) of time-lapse movies from time 0 s to the time points indicated. Actin filament positions at the latter time point are highlighted. (b,d) Maximum projections (from 4 s time-lapse movies at lower magnification) of gliding actin filaments before (b) and after (d) regeneration. (e,g) Fluorescence micrographs zooming in on few microtubules gliding on kinesin-coated glass substrates before (e) and after (g) regeneration. Again, the images show maximum projections of time-lapse movies from time 0 s to the time points indicated. Microtubule positions at the latter time point are highlighted. (f,h) Maximum projections (from 121 s time-lapse movies at lower magnification) of gliding microtubules before (f) and after (h) regeneration. Note that the time between frames for HMM-propelled actin filaments is appreciably shorter than for kinesin-propelled microtubules due to higher velocity. Also, the gliding paths are appreciably more curved for the actin filaments due to >10-fold lower persistence length than for microtubules. See Movies S1, S2, S3, and S4 for videos corresponding to data in this figure.

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We first consider the actin–myosin system in more detail. Regeneration restored smooth gliding with a high fraction of motile filaments and a gliding velocity that was similar as before the treatment (Figure 2a–d, Movies S1 and S2, and Figure 3a). Evaluation of filament lengths (Figure 3b) and plots of velocity versus filament lengths (Figure S4) provides more insight. Because of the short on-time of a myosin motor domain on the actin filament in each cyclic interaction, low actin gliding velocities are expected if only few motors interact with the actin filaments, such as in the case of short actin filaments and/or low motor densities. (44) Therefore, velocity versus filament-length plots sensitively reflect the HMM surface density. Moreover, if there are fewer motors on the surface, the average length of the gliding filaments is expected to be higher because of reduced filament fragmentation due to myosin imposed forces. (44)

Figure 3

Figure 3. Analysis of motility performance after regeneration. (a) Actin gliding velocity at 25.1–26 °C produced by HMM adsorbed to TMCS-derivatized SiO2 surfaces; “Surface 1” and “Surface 2” represent two different surfaces tested in two different experiments and were regenerated either once (no further regeneration was attempted intentionally) or three times. In each individual experiment, 10–24 actin filaments were analyzed. (b) Actin filament length distribution for filaments propelled by myosin adsorbed to one TMCS-derivatized SiO2 surface before and after each of three regeneration cycles for “Surface 2” in (a). (c) Average microtubule gliding velocity at 25 °C in a kinesin motility assay on glass surfaces. The control value shown is the mean gliding velocity of surfaces 1–3 before regeneration. Surface 1 was regenerated directly after the control gliding assay and was tested without letting the channel dry in between. Surface 2 was processed similarly but the channel was dried before the regeneration procedure. Finally, surface 3 was regenerated and dried afterward before performing a new gliding assay. Subsequently, surface 3 was regenerated a second time (drying before regeneration) and a third time (without drying). In each individual experiment, the velocity of 277–731 microtubules was analyzed. (d) Microtubule length distribution and median length of the assays depicted in (c). The control bar represents an assay before regeneration. Velocity data are given as mean ±95% confidence interval.

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Our results, showing that both the velocity versus filament-length relationship (Figure S4) and the average filament length (Figure 3b) are similar before and after regeneration, therefore support efficient regeneration. This finding is consistent with contact angle measurements and analysis by Coomassie stain discussed above (Figure 1). Moreover, we could demonstrate a proof-of-principle repeatability of the regeneration procedure without decline in HMM-driven actin filament velocity (Figure 3a) by studying three subsequent regeneration cycles. Because each cycle is, nevertheless, likely associated with some deterioration either due to minimal accumulations of protein remnants on the surface or accidental failure of some step in a given regeneration cycle it is not surprising that we find a slightly increased actin filament length after the third cycle in Figure 3b. However, importantly, the lack of any trend toward a decline in velocity with repeated cycles suggests (Figure 3a) that any accumulating negative effects are of limited significance.

The results with the microtubule–kinesin system (Figures 2e–h, 3c,d) were analogous to those with the actin–myosin system. After regenerating the flow cell using the optimized protocol (Figure 1) and adsorbing new kinesin molecules, microtubules moved smoothly and the fraction of nonmotile filaments did not increase (Figure 2e–h, Movies S3 and S4, and Table S2). The microtubule gliding velocities, which are independent of the kinesin density on the surface, (20) remained nearly constant upon regeneration (Figure 3c). Although the length distribution of gliding microtubules is generally dependent on the actual population, the length of the shortest gliding filaments allows some conclusion about the actual active kinesin density. (47) Thus, because the length distributions before (control) and in all conditions after the regeneration are comparable with respect to the shortest filaments (Figure 3d), we can assume that a similar motor density is achieved after regenerating the surface. When testing whether it was possible to repeatedly regenerate surfaces for kinesin-microtubule motility, we observe, in analogy to our results earlier for the actin–myosin system, no decrease in microtubule gliding velocities even after a third regeneration (Figure 3c). This suggests that there is no significant accumulation of negative effects in each regeneration cycle and that substantially more regeneration cycles will be possible than the three cycles demonstrated here. The small differences in velocity before and after regeneration (Figure 3c) are within the range of variability resulting from small temperature differences (1 K) in our setup. (48) The fact that repeatable regeneration was verified for both motor systems suggests no critical dependence of the regeneration procedure on the motor system or on the underlying surface substrate.

Because the motility-supporting surfaces may dry out between repeated cycles of usage, we examined the possibility of drying the surfaces before or after regeneration. The procedure was tested for the microtubule–kinesin system on glass surfaces and was found to yield almost as successful a regeneration as without drying (Figure 3c,d; Table S2). However, a slight decrease of microtubule gliding velocity was observed, especially in the case of drying the surface before regeneration. The decrease of the mean velocity was probably due to some transiently nonmotile, short filaments as the fraction of permanently nonmotile filaments was only slightly increased. Therefore, regenerating the device immediately after usage and subsequently drying it for storage might be more reliable.

After having demonstrated the successful regeneration of planar surfaces, we tested our optimized protocol on topographically structured surfaces that were also chemically patterned to support motility only in predefined areas. For the microtubule–kinesin system, this was realized using structured SiO2 on top of a gold-coated silicon wafer (Figure 4a). The SiO2 walls were chemically modified with PEG to prevent protein binding, that is, to restrict motility to the gold floors of the structures. Similar structures have been used earlier for kinesin-based nano/microdevices. (31,49) The control motility assay showed smooth gliding of filaments and motility was restricted to the gold-coated floors of the “flower” structures (Figure 4b). The microtubule gliding velocities were around 700 nm/s and remained approximately constant over time (Figure 4c). After regenerating the surface and adsorbing new proteins, motility was still observed only on the floors, clearly demonstrating that the chemical selectivity due to the PEG-coating of the SiO2 walls was not compromised by the regeneration procedure. The microtubule gliding velocities after regeneration slightly increased above the control value to about 740 nm/s but remained constant over time. The small velocity increase may again be explained by a slight increase of the ambient temperature in the course of the experiment. Moreover, microtubules were reliably guided at the silicon oxide walls (Figure 4d) and did not get stuck more frequently: the fraction of stuck microtubules after regeneration fregeneration = 0.09 was comparable to the control value fcontrol = 0.07. Besides the flower structures, with rather large motility-supporting areas, structures with narrow channels (<1 μm in width) are useful for nano/microdevices, for example, in biocomputation and biosensing. When regenerating such structures we likewise obtained fully restored motility (Figure 4e) and the number of nonmotile filaments did not increase.

Figure 4

Figure 4. Regeneration of an assembled nano/microdevice with embedded microstructures for the microtubule–kinesin system. (a) Schematic cross-section of a microstructured SiO2 surface used for regeneration. On these surfaces, motility was restricted to the gold layers on the patterned, gold-coated floor. The rest of the surface was rendered protein-repellent by a PEG coating. (b) Maximum projections (from 10 min time-lapse movies) of fluorescently labeled microtubules gliding on kinesin-coated gold floors before (“Control”) and after regeneration. (c) Microtubule gliding velocity at different time points before and after regeneration; N = 3 surfaces. At each individual time point, 637–1216 microtubules were analyzed. Data are given as mean ±95% confidence interval. (d) Time series of fluorescence micrographs showing microtubule gliding within one “petal” of the flower structure as depicted in (b) before and after regeneration. The positions of three microtubules are marked along with their trajectories. (e) Average projections as well as maximum projections of fluorescently labeled microtubules gliding within 1 μm wide channels with kinesin-coated gold floors before (“Control”) and after regeneration. The projections were derived from 30 min time-lapse movies. See also Movies S5 and S6.

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We also tested the method by regenerating a chemically and topographically patterned SiO2 surface adapted for the actin–myosin system and produced using selective spin-cleaning with PDMS (Figure S5). In this case, half of the surface was covered with the motility-inhibiting CSAR62 polymer resist (50) that may be used for nanofabrication of structures on a SiO2 chip. (51) We found that the motility inhibition in the area covered with CSAR62 polymer resist was not altered by the regeneration procedure whereas the TMCS derivatized SiO2 surface area without CSAR62 resist was fully regenerated. When regenerating a topographically and chemically patterned SiO2 surface produced using electron beam lithography (EBL; Figure 5), we found that a similar treatment as described above generally does not lead to successful regeneration of nano/microstructures for actomyosin motility with TMCS-derivatized SiO2 surrounded by motility suppressing CSAR62 polymer resist. We considered the possibility that this is due to a lack of compatibility of CSAR62 with extended aqueous treatment. To test this idea, we submerged nanostructures under water for 8 h but did not observe resist lift off or other changes. We then hypothesized that the use of SDS may cause the problem as the long hydrocarbon chains of SDS may interact with the ester groups of the CSAR62 polymer resist and change the polymer properties. Moreover, SDS is anionic with appreciable net negative charge and may transfer negative charges to the CSAR62 polymer resist. The idea that the use of SDS is the basis for the problems with regeneration of nanostructured surfaces is supported by results of experiments where SDS was substituted with the nonionic detergent Triton X100 (0.05%). In contrast to SDS, Triton X100 has neither the long hydrocarbon chains nor negative charges. Interestingly, we found that Triton X100 is equally effective as SDS for regeneration of both trimethylchlorosilane derivatized glass and SiO2 surfaces (Figure 5) that otherwise use the standard protocol (Figure 1). Both the actin gliding velocities and the mean filament lengths were maintained at the control value after regeneration suggesting that the HMM surface density is unchanged compared to motility assays before regeneration (Figure S4). Furthermore, motility was maintained on the TMCS-derivatized loading zone of the nanostructured chips (produced by EBL) with similar quality as before regeneration (Figure 5b,c; Movies S7 and S8). Most importantly, as desired there was no motility on the surrounding resist areas. It will be of value to test and, if necessary, optimize the regeneration protocol also for narrow, submicron-wide TMCS-derivatized channels applied for the actin–myosin system.

Figure 5

Figure 5. Regeneration of an assembled motility device with embedded nano/microstructures for the actin–myosin system applying the detergent Triton X100 (instead of SDS). (a) Schematic design of the structured SiO2 surface used for regeneration with topographically and chemically defined areas. The structure was produced by electron beam lithography to produce CSAR62 polymer walls and surroundings (pink) of trimethylchlorosilane-derivatized-SiO2 channels (blue). HMM motors bind to the TMCS-derivatized floors in a motility-promoting manner, whereas binding to the surrounding CSAR 62 polymer walls is inhibited. (51) The large heart shaped structure acts as a loading zone for the actin filaments with the aim to guide them into the 500 nm wide feedback channel. (b) Maximum projections (from 4 s time-lapse movies) showing actin filament gliding driven by HMM motors adsorbed to TMCS-derivatized SiO2 in the heart-shaped structure before (“Control”) and after regeneration. Feeding filaments into the channels were observed in this particular structure neither before nor after regeneration. Note, filaments floating in solution are seen as quite bright objects (due to relatively stationary position) above areas outside the loading zone in the Control. See also Movies S7 and S8. (c) HMM-propelled actin gliding velocity on TMCS-derivatized SiO2 surfaces; N = 2 surfaces, where the first surface was a flat chip and regenerated twice and the second surface had an embedded nanostructure. On the flat SiO2 chip, 18–25 actin filaments were analyzed and on the heart-shaped structure, 3–12 filaments were analyzed. Temperature 26.0–26.6 °C. Data are given as mean ±95% confidence interval.

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Taken together, our results indicate that the described regeneration procedure is equally suitable for topographically structured surfaces as for flat surfaces and that it preserves chemical selectivity. Although the use of SDS as detergent is suitable in most cases it may need to be substituted by other detergents (e.g., Triton X100; Figure 5). Regeneration of 1 μm wide channels, applicable in biosensing and biocomputation devices based on the microtubule–kinesin system, could be successfully demonstrated (Figure 4e) whereas the regeneration of nanoscale channels suitable for actin–myosin based devices remain to be evaluated.

In summary, we developed and tested a method to regenerate biomolecular-motor-based nano/microdevices, assembled together with a fluidic system. The method is useful for both the actin–myosin and microtubule–kinesin systems and it allows repeated use of the devices without damaging or dissembling the fluidic system. Our findings are important because the regenerated structures were surface-functionalized as in recent nanostructured devices (31,51) for motor-driven biocomputation or biosensing applications. In the future, possibly after further optimizations, the method may become even more important for more sophisticated bionanodevices, for example, devices with integrated nanowires and/or nanoelectronic structures for automated electrical or optical signal read-out. Furthermore, we expect that the method will find general use for the regeneration of bionanodevices as well as of nonpatterned surfaces, for example, in biosensors, also when nonmotor proteins are the key biological elements.

Supporting Information

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The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.nanolett.9b02738.

  • Methodological details for all parts of the manuscript, supplementary results considering Figures S1–S5 in greater detail. Supplementary figures and tables contain information as follows: Regeneration of trimethylchlorosilane derivatized glass surfaces only with SDS (Figure S1), efficiency of regenerating trimethylchlorosilane derivatized glass surfaces with only Proteinase K. (Figure S2), efficiency of SDS (0–5%) inclusion after Proteinase K (1h) treatment for regenerating trimethylchlorosilane derivatized glass surfaces (Figure S3), efficiency of the optimized regeneration protocol on flat as well as on micro/nanostructured surfaces with Triton X100 as detergent (Figure S4), regeneration of TMCS-derivatized and ARP (CSAR62) micropatterned surface for actomyosin motility (Figure S5), summary of findings with different approaches to test recycling of trimethylchlorosilane derivatized glass surfaces (Table S1), and fraction of stuck microtubules in a motility assay before (control) and after surface regeneration (Table S2) (PDF)

  • In vitro motility assay, using actin–myosin system, on HMM-coated TMCS-derivatized SiO2 surface before surface regeneration (AVI)

  • In vitro motility assay, using actin–myosin system, on HMM-coated TMCS-derivatized SiO2 surface after surface regeneration (AVI)

  • In vitro motility assay, using microtubule–kinesin system, on a glass-surface before surface regeneration (AVI)

  • In vitro motility assay, using microtubule–kinesin system, on glass-surface after surface regeneration (AVI)

  • In vitro motility assay, using microtubule–kinesin system, within channels (width = 1 μm) on a structured SiO2-surface before surface regeneration (AVI)

  • Representative in vitro motility assay, using microtubule–kinesin system, within channels (width = 1 μm) on a structured SiO2-surface after surface regeneration (AVI)

  • In vitro motility assay, using actin–myosin system, on HMM-coated TMCS-derivatized nanostructured surface before surface regeneration (AVI)

  • In vitro motility assay, using actin–myosin system, on HMM-coated TMCS-derivatized nanostructured surface after surface regeneration (AVI)

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Author Information

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  • Corresponding Authors
  • Authors
    • Mohammad A. Rahman - Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden, 39182;  NanoLund and , Lund University, Lund, Sweden, 22100;  Orcidhttp://orcid.org/0000-0002-2797-2294
    • Cordula Reuther - B CUBE − Center for Molecular Bioengineering, Technische Universität Dresden, Sachsen, Germany, 01062;  Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
    • Frida W. Lindberg - Division of Solid State Physics  and  NanoLund and , Lund University, Lund, Sweden, 22100;  Orcidhttp://orcid.org/0000-0001-5617-6337
    • Martina Mengoni - B CUBE − Center for Molecular Bioengineering, Technische Universität Dresden, Sachsen, Germany, 01062;  Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
    • Aseem Salhotra - Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden, 39182;  NanoLund and , Lund University, Lund, Sweden, 22100
    • Georg Heldt - Fraunhofer Institute for Electronic Nano Systems, Chemnitz, Germany 09126
    • Heiner Linke - Division of Solid State Physics  and  NanoLund and , Lund University, Lund, Sweden, 22100
  • Author Contributions

    M.A.R. and C.R. contributed equally

  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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This work was funded by European Union Seventh Framework FET Programme under contract 613044 (ABACUS) and the European Union Horizon2020 FET Program under contract 732482 (Bio4comp), The Swedish Research Council (Grant 2015-05290), The Faculty of Health and Life Sciences at The Linnaeus University, NanoLund at Lund University, and the Technische Universität Dresden.

References

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This article references 51 other publications.

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    Protein adsorption on solid surfaces
    Hlady, Vladimir; Buijs, Jos
    Current Opinion in Biotechnology (1996), 7 (1), 72-7CODEN: CUOBE3; ISSN:0958-1669. (Current Biology)
    A review with 67 refs. The research field of protein adsorption on surfaces appears to be as popular as ever. In the past year, several hundred published papers tackled problems ranging from fundamental aspects of protein surface interactions to applied problems of surface blood compatibility and protein adsorption process, such as kinetics and equil. interactions, can be accurately predicted, other aspects, such as the extent and the rate of protein conformational change, are still somewhat uncertain. The whole field is ripe for a comprehensive theory on protein adsorption.
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    Nakanishi, K.; Sakiyama, T.; Imamura, K. On the adsorption of proteins on solid surfaces, a common but very complicated phenomenon. J. Biosci. Bioeng. 2001, 91, 233– 244,  DOI: 10.1016/S1389-1723(01)80127-4
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    On the adsorption of proteins on solid surfaces, a common but very complicated phenomenon
    Nakanishi, Kazuhiro; Sakiyama, Takaharu; Imamura, Koreyoshi
    Journal of Bioscience and Bioengineering (2001), 91 (3), 233-244CODEN: JBBIF6; ISSN:1389-1723. (Society for Bioscience and Bioengineering, Japan)
    A review, with 91 refs. Adsorption of proteins on solid surfaces and their interaction are major concerns in a no. of fields such as biol., medicine, biotechnol. and food processing, and play an important role from various points of view. Based on practical viewpoints, information on the conformation of the adsorbed protein as well as adsorption characteristics is essential for a system's performance. Although there are still many problems to be solved, extensive studies in recent years, owing to the development in instrumentation and instrumental techniques, reveal the adsorption behavior of proteins in detail. Here, we stress the importance and interesting aspect of protein adsorption on solid surfaces by reviewing findings that have been obtained in recent years.
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    Rabe, M.; Verdes, D.; Seeger, S. Understanding protein adsorption phenomena at solid surfaces. Adv. Colloid Interface Sci. 2011, 162, 87– 106,  DOI: 10.1016/j.cis.2010.12.007
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    Understanding protein adsorption phenomena at solid surfaces
    Rabe, Michael; Verdes, Dorinel; Seeger, Stefan
    Advances in Colloid and Interface Science (2011), 162 (1-2), 87-106CODEN: ACISB9; ISSN:0001-8686. (Elsevier B.V.)
    A review. Protein adsorption at solid surfaces plays a key role in many natural processes and has therefore promoted a widespread interest in many research areas. Despite considerable progress in this field there are still widely differing and even contradictive opinions on how to explain the frequently obsd. phenomena such as structural rearrangements, cooperative adsorption, overshooting adsorption kinetics, or protein aggregation. In this review recent achievements and new perspectives on protein adsorption processes are comprehensively discussed. The main focus is put on commonly postulated mechanistic aspects and their translation into math. concepts and model descriptions. Relevant exptl. and computational strategies to practically approach the field of protein adsorption mechanisms and their impact on current successes are outlined.
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    Kasemo, B. Biological surface science. Surf. Sci. 2002, 500, 656– 677,  DOI: 10.1016/S0039-6028(01)01809-X
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    Biological surface science
    Kasemo, Bengt
    Surface Science (2002), 500 (1-3), 656-677CODEN: SUSCAS; ISSN:0039-6028. (Elsevier Science B.V.)
    A review. Biol. surface science (BioSS), as defined here is the broad interdisciplinary area where properties and processes at interfaces between synthetic materials and biol. environments are investigated, and biofunctional surfaces are fabricated. Six examples are used to introduce and discuss the subject: Medical implants in the human body, biosensors and biochips for diagnostics, tissue engineering, bioelectronics, artificial photosynthesis, and biomimetic materials. They are areas of varying maturity, together constituting a strong driving force for the current rapid development of BioSS. The second driving force is the purely scientific challenges and opportunities to explore the mutual interaction between biol. components and surfaces. Model systems range from the unique water structures at solid surfaces and water shells around proteins and biomembranes, via amino and nucleic acids, proteins, DNA, phospholipid membranes, to cells and living tissue at surfaces. At one end of the spectrum the scientific challenge is to map out the structures, bonding, dynamics and kinetics of biomols. at surfaces in a similar way as has been done for simple mols. during the past three decades in surface science. At the other end of the complexity spectrum one addresses how biofunctional surfaces participate in and can be designed to constructively participate in the total communication system of cells and tissue. Biofunctional surfaces call for advanced design and prepn. in order to match the sophisticated (bio) recognition ability of biol. systems. Specifically this requires combined topog., chem. and visco-elastic patterns on surfaces to match proteins at the nm scale and cells at the micrometer scale. Essentially all methods of surface science are useful. High-resoln. (e.g. scanning probe) microscopies, spatially resolved and high sensitivity, non-invasive optical spectroscopies, self-organizing monolayers, and nano- and microfabrication are important for BioSS. However, there is also a need to adopt or develop new methods for studies of biointerfaces in the native, liq. state. For the future it is likely that BioSS will have an even broader definition than above and include native interfaces, and that combinations of mol. (cell) biol., and BioSS will contribute to the understanding of the "living state".
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    Castner, D. G.; Ratner, B. D. Biomedical surface science: Foundations to frontiers. Surf. Sci. 2002, 500, 28– 60,  DOI: 10.1016/S0039-6028(01)01587-4
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    Biomedical surface science: Foundations to frontiers
    Castner, David G.; Ratner, Buddy D.
    Surface Science (2002), 500 (1-3), 28-60CODEN: SUSCAS; ISSN:0039-6028. (Elsevier Science B.V.)
    A review. Surfaces play a vital role in biol. and medicine with most biol. reactions occurring at surfaces and interfaces. The foundations, evolution, and impact of biomedical surface science are discussed. In the 19th century, the first observations were made that surfaces control biol. reactions. The advancements in surface science instrumentation that have occurred in the past quarter of a century have significantly increased our ability to characterize the surface compn. and mol. structure of biomaterials. Similar advancements have occurred in material science and mol. biol. The combination of these advances have allowed the development of the biol. model for surface science, where the ultimate goal is to gain a detailed understanding of how the surface properties of a material control the biol. reactivity of a cell interacting with that surface. Numerous examples show that the surface properties of a material are directly related to in vitro biol. performance such as protein adsorption and cell growth. The challenge is to fully develop the biol. model for surface science in the highly complex and interactive in vivo biol. environment. Examples of state-of-the-art biomedical surface science studies on surface chem. state imaging, mol. recognition surfaces, adsorbed protein films, and hydrated surfaces are presented. Future directions and opportunities for surface scientists working in biomedical research include exploiting biol. knowledge, biomimetics, precision immobilization, self-assembly, nanofabrication, smart surfaces, and control of non-specific reactions.
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    Kumar, S.; ten Siethoff, L.; Persson, M.; Albet-Torres, N.; Månsson, A. Magnetic capture from blood rescues molecular motor function in diagnostic nanodevices. J. Nanobiotechnol. 2013, 11, 14,  DOI: 10.1186/1477-3155-11-14
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    Magnetic capture from blood rescues molecular motor function in diagnostic nanodevices
    Kumar, Saroj; ten Siethoff, Lasse; Persson, Malin; Albet-Torres, Nuria; Maansson, Alf
    Journal of Nanobiotechnology (2013), 11 (), 14CODEN: JNOAAO; ISSN:1477-3155. (BioMed Central Ltd.)
    Background: Introduction of effective point-of-care devices for use in medical diagnostics is part of strategies to combat accelerating health-care costs. Mol. motor driven nanodevices have unique potentials in this regard due to unprecedented level of miniaturization and independence of external pumps. However motor function has been found to be inhibited by body fluids. Results: We report here that a unique procedure, combining sepn. steps that rely on antibody-antigen interactions, magnetic forces applied to magnetic nanoparticles (MPs) and the specificity of the actomyosin bond, can circumvent the deleterious effects of body fluids (e.g. blood serum). The procedure encompasses the following steps: (i) capture of analyte mols. from serum by MP-antibody conjugates, (ii) pelleting of MP-antibody-analyte complexes, using a magnetic field, followed by exchange of serum for optimized biol. buffer, (iii) mixing of MP-antibody-analyte complexes with actin filaments conjugated with same polyclonal antibodies as the magnetic nanoparticles. This causes complex formation: MP-antibody-analyte-antibody-actin, and magnetic sepn. is used to enrich the complexes. Finally (iv) the complexes are introduced into a nanodevice for specific binding via actin filaments to surface adsorbed mol. motors (heavy meromyosin). The no. of actin filaments bound to the motors in the latter step was significantly increased above the control value if protein analyte (50-60 nM) was present in serum (in step i) suggesting appreciable formation and enrichment of the MP-antibody-analyte-antibody-actin complexes. Furthermore, addn. of ATP demonstrated maintained heavy meromyosin driven propulsion of actin filaments showing that the serum induced inhibition was alleviated. Detailed anal. of the procedure i-iv, using fluorescence microscopy and spectroscopy identified main targets for future optimization. Conclusion: The results demonstrate a promising approach for capturing analytes from serum for subsequent motor driven sepn./detection. Indeed, the obsd. increase in actin filament no., in itself, signals the presence of analyte at clin. relevant nM concn. without the need for further motor driven concn. Our anal. suggests that exchange of polyclonal for monoclonal antibodies would be a crit. improvement, opening for a first clin. useful mol. motor driven lab-on-a-chip device.
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    Frasconi, M.; Mazzei, F.; Ferri, T. Protein immobilization at gold-thiol surfaces and potential for biosensing. Anal. Bioanal. Chem. 2010, 398, 1545,  DOI: 10.1007/s00216-010-3708-6
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    Protein immobilization at gold-thiol surfaces and potential for biosensing
    Frasconi, Marco; Mazzei, Franco; Ferri, Tommaso
    Analytical and Bioanalytical Chemistry (2010), 398 (4), 1545-1564CODEN: ABCNBP; ISSN:1618-2642. (Springer)
    A review. Self-assembled monolayers (SAMs) provide a convenient, flexible and simple system to tailor the interfacial properties of metals, metal oxides and semiconductors. Monomol. films prepd. by self-assembly are attractive for several exciting applications because of the unique possibility of making the selection of different types of terminal functional groups and as emerging tools for nanoscale observation of biol. interactions. The tenability of SAMs as platforms for prepg. biosurfaces is reviewed and critically discussed. The different immobilization approaches used for anchoring proteins to SAMs are considered as well as the nature of SAMs; particular emphasis is placed on the chem. specificity of protein attachment in view of preserving protein native structure necessary for its functionality. Regarding this aspect, particular attention is devoted to the relation between the immobilization process and the electrochem. response (i.e. electron transfer) of redox proteins, a field where SAMs have attracted remarkable attention as model systems for the design of electronic devices. Strategies for creating protein patterns on SAMs are also outlined, with an outlook on promising and challenging future directions for protein biochip research and applications.
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    Arlett, J. L.; Myers, E. B.; Roukes, M. L. Comparative advantages of mechanical biosensors. Nat. Nanotechnol. 2011, 6, 203– 215,  DOI: 10.1038/nnano.2011.44
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    Comparative advantages of mechanical biosensors
    Arlett, J. L.; Myers, E. B.; Roukes, M. L.
    Nature Nanotechnology (2011), 6 (4), 203-215CODEN: NNAABX; ISSN:1748-3387. (Nature Publishing Group)
    A review. Mech. interactions are fundamental to biol. Mech. forces of chem. origin det. motility and adhesion on the cellular scale, and govern transport and affinity on the mol. scale. Biol. sensing in the mech. domain provides unique opportunities to measure forces, displacements and mass changes from cellular and subcellular processes. Nanomech. systems are particularly well matched in size with mol. interactions, and provide a basis for biol. probes with single-mol. sensitivity. Here we review micro- and nanoscale biosensors, with a particular focus on fast mech. biosensing in fluid by mass- and force-based methods, and the challenges presented by non-specific interactions. We explain the general issues that will be crit. to the success of any type of next-generation mech. biosensor, such as the need to improve intrinsic device performance, fabrication reproducibility and system integration. We also discuss the need for a greater understanding of analyte-sensor interactions on the nanoscale and of stochastic processes in the sensing environment.
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    Sharma, S.; Byrne, H.; O’Kennedy, R. J. Antibodies and antibody-derived analytical biosensors. Essays Biochem. 2016, 60, 9– 18,  DOI: 10.1042/EBC20150002
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    Antibodies and antibody-derived analytical biosensors
    Sharma Shikha; Byrne Hannah; O'Kennedy Richard J
    Essays in biochemistry (2016), 60 (1), 9-18 ISSN:.
    The rapid diagnosis of many diseases and timely initiation of appropriate treatment are critical determinants that promote optimal clinical outcomes and general public health. Biosensors are now being applied for rapid diagnostics due to their capacity for point-of-care use with minimum need for operator input. Antibody-based biosensors or immunosensors have revolutionized diagnostics for the detection of a plethora of analytes such as disease markers, food and environmental contaminants, biological warfare agents and illicit drugs. Antibodies are ideal biorecognition elements that provide sensors with high specificity and sensitivity. This review describes monoclonal and recombinant antibodies and different immobilization approaches crucial for antibody utilization in biosensors. Examples of applications of a variety of antibody-based sensor formats are also described.
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    Hock, B.; Seifert, M.; Kramer, K. Engineering receptors and antibodies for biosensors. Biosens. Bioelectron. 2002, 17, 239– 249,  DOI: 10.1016/S0956-5663(01)00267-6
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    Engineering receptors and antibodies for biosensors
    Hock, B.; Seifert, M.; Kramer, K.
    Biosensors & Bioelectronics (2002), 17 (3), 239-249CODEN: BBIOE4; ISSN:0956-5663. (Elsevier Science S.A.)
    A review. Biosensor sensitivity and selectivity depend essentially on the properties of the biorecognition elements to be used for analyte binding. Two principally different applications are considered, effects monitoring with biol. components as targets for bioeffective substances, among them endocrine disruptors; and immunochem. anal. employing antibodies as binding proteins for a wide variety of analytes such as pesticides. Genetic engineering provides an elegant way not only for providing unlimited amts. of biorecognition mols. but also for the alteration of existing properties and the supplementation with addnl. functions. Instrumental applications were carried out with the optical sensor BIAcore. The first example deals with the characterization of receptors. For this purpose, the human estrogen receptor α was used. Binding studies were carried out with natural as well as xenoestrogens. An equil. dissocn. const. Kd of 2.3 × 10-10 (M) was derived for 17β-estradiol. A competition assay was performed with a bovine serum albumin (BSA)-17β-estradiol conjugate, immobilized at the optical sensor surface, and the free estrogen. The signals obtained represent estradiol equiv. This format was transferred to a microplate-based enzyme-linked receptor assay. It reached a detection limit of 0.02 μg l-1 17β-estradiol and proved suitable for the detection of natural and synthetic estrogens as well as xenoestrogens in field studies. The second example is targeted at kinetic and affinity measurements of recombinant antibody fragments derived from antibody libraries with s-triazine selectivities. Different strategies for the synthesis of antibody fragment libraries, followed by the selection of specific antibody variants, were examd. An antibody library was derived from a set of B cells. Chain shuffling of the heavy and light chains provided the best binders. An enzyme linked immunosorbent assay (ELISA) was achieved for atrazine with an IC50 of 0.9 μg l-1 and a detection limit of 0.2 μg l-1. The close relations between the optimization of recombinant antibodies by evolutionary strategies and genetic algorithms are considered.
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    Sugimoto, K.; Tsuchiya, S.; Omori, M.; Matsuda, R.; Fujio, M.; Kuroda, K.; Okido, M.; Hibi, H. Proteomic analysis of bone proteins adsorbed onto the surface of titanium dioxide. Biochem. Biophys. Reports 2016, 7, 316– 322,  DOI: 10.1016/j.bbrep.2016.07.007
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    Proteomic analysis of bone proteins adsorbed onto the surface of titanium dioxide
    Sugimoto Keisuke; Omori Masahiro; Matsuda Ryo; Fujio Masahito; Hibi Hideharu; Tsuchiya Shuhei; Kuroda Kensuke; Okido Masazumi
    Biochemistry and biophysics reports (2016), 7 (), 316-322 ISSN:2405-5808.
    Osseointegration is the structural and functional connection between bone tissues and implants such as titanium dioxide (TiO2). The bone-TiO2 interface is thought to contain proteoglycans. However, exhaustive analysis of the proteins in this layer has not been performed. In this study, we evaluated the bone protein adhered on the surface of TiO2 comprehensively. Pig bone protein was extracted by sequential elutions with guanidine, 0.1 M EDTA, and again with guanidine. The proteins obtained from these extractions were allowed to adhere to an HPLC column packed with TiO2 and were eluted with 0.2 M NaOH. The eluted proteins were identified by LC/MS/MS and included not only proteoglycans but also other proteins such as extracellular matrix proteins, enzymes, and growth factors. Calcium depositions were observed on TiO2 particles incubated with bone proteins, guanidine-extracted proteins adhered to TiO2 displayed significantly high amounts of calcium depositions.
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    Dodo, C. G.; Senna, P. M.; Custodio, W.; Paes Leme, A. F.; Del Bel Cury, A. A. Proteome analysis of the plasma protein layer adsorbed to a rough titanium surface. Biofouling 2013, 29, 549– 557,  DOI: 10.1080/08927014.2013.787416
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    Proteome analysis of the plasma protein layer adsorbed to a rough titanium surface
    Dodo, Cindy Goes; Senna, Plinio Mendes; Custodio, William; Paes Leme, Adriana Franco; Del Bel Cury, Altair Antoninha
    Biofouling (2013), 29 (5), 549-557CODEN: BFOUEC; ISSN:0892-7014. (Taylor & Francis Ltd.)
    In this study a label-free proteomic approach was used to investigate the compn. of the layer of protein adsorbed to rough titanium (Ti) after exposure to human blood plasma. The influence of the protein layer on the surface free energy (SFE) of the Ti was evaluated by contact angle measurements. Ti disks were incubated with blood plasma for 180 min at 37 °C, and the proteins recovered were subjected to liq. chromatog. coupled to tandem mass spectrometry anal. A total of 129 different peptides were identified and assigned to 25 distinct plasma proteins. The most abundant proteins were fibronectin, serum albumin, apolipoprotein A-I, and fibrinogen, comprising 74.54% of the total spectral counts. Moreover, the protein layer increased the SFE of the Ti (p < 0.05). The layer adsorbed to the rough Ti surface was composed mainly of proteins related to cell adhesion, mol. transportation, and coagulation processes, creating a polar and hydrophilic interface for subsequent interactions with host cells.
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    Wong, J. Y.; Kuhl, T. L.; Israelachvili, J. N.; Mullah, N.; Zalipsky, S. Direct Measurement of a Tethered Ligand-Receptor Interaction Potential. Science (Washington, DC, U. S.) 1997, 275, 820,  DOI: 10.1126/science.275.5301.820
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    Direct measurement of a tethered ligand-receptor interaction potential
    Wong, Joyce Y.; Kuhl, Tonya L.; Israelachvili, Jacob N.; Mullah, Nasreen; Zalipsky, Samuel
    Science (Washington, D. C.) (1997), 275 (5301), 820-822CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
    Many biol. recognition interactions involve ligands and receptors are tethered rather than rigidly bound on a cell surface. A surface forces app. was used to directly measure the force-distance interaction between a polymer-tethered ligand and its receptor. At sepns. near the fully extended tether length, the ligands rapidly lock onto the their binding sites, pulling the ligand and receptor together. The measured interaction potential and its dynamics be modeled with std. theories of polymer and colloidal interactions.
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    Bell, S.; Terentjev, E. M. Specific binding of a polymer chain to a sequence of surface receptors. Sci. Rep. 2017, 7, 17272,  DOI: 10.1038/s41598-017-17581-x
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    Specific binding of a polymer chain to a sequence of surface receptors
    Bell Samuel; Terentjev Eugene M
    Scientific reports (2017), 7 (1), 17272 ISSN:.
    This paper considers a biologically relevant question of a Gaussian chain (such as an unfolded protein) binding to a sequence of receptors with matching multiple ligands distributed along the chain. Using the characteristic time for a tethered ligand to bind to a surface receptor, we study the case of multiple binding to a linear sequence of receptors on the surface. The tethered binding time is determined by the entropic barrier for the chain to be stretched sufficiently to reach the distant receptor target, and a restriction on chain conformations near the substrate. Adsorption (multiple-site binding) is shown to be dominated by a simple zipper sequence, only occasionally accelerated by loop formation. However, when the number of receptors increases, a competing rate-limiting process takes over: the center of mass of the remaining free chain has to drift down the line of receptors, which takes longer when the receptors are close and the entropic pulling force is low. As a result, the time for the complete chain adsorption is minimised by a certain optimal number of receptors, depending on the distance to be traversed by the free end, and the chain length.
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    Xu, L.-C.; Bauer, J. W.; Siedlecki, C. A. Proteins, platelets, and blood coagulation at biomaterial interfaces. Colloids Surf., B 2014, 124, 49– 68,  DOI: 10.1016/j.colsurfb.2014.09.040
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    Proteins, platelets, and blood coagulation at biomaterial interfaces
    Xu, Li-Chong; Bauer, James W.; Siedlecki, Christopher A.
    Colloids and Surfaces, B: Biointerfaces (2014), 124 (), 49-68CODEN: CSBBEQ; ISSN:0927-7765. (Elsevier B.V.)
    A review. Blood coagulation and platelet adhesion remain major impediments to the use of biomaterials in implantable medical devices. There is still significant controversy and question in the field regarding the role that surfaces play in this process. This manuscript addresses this topic area and reports on state of the art in the field. Particular emphasis is placed on the subject of surface engineering and surface measurements that allow for control and observation of surface-mediated biol. responses in blood and test solns. Appropriate use of surface texturing and chem. patterning methodologies allow for redn. of both blood coagulation and platelet adhesion, and new methods of surface interrogation at high resoln. allow for measurement of the relevant biol. factors.
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    Kron, S. J.; Spudich, J. A. Fluorescent actin filaments move on myosin fixed to a glass surface. Proc. Natl. Acad. Sci. U. S. A. 1986, 83, 6272– 6276,  DOI: 10.1073/pnas.83.17.6272
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    Fluorescent actin filaments move on myosin fixed to a glass surface
    Kron, Stephen J.; Spudich, James A.
    Proceedings of the National Academy of Sciences of the United States of America (1986), 83 (17), 6272-6CODEN: PNASA6; ISSN:0027-8424.
    Single actin filaments stabilized with fluorescent phalloidin exhibit ATP-dependent movement on myosin filaments fixed to a surface. At pH 7.4 and 24°, the rates of movement av. 3-4 μm/s with skeletal muscle myosin and 1-2 μm/s with Dictyostelium myosin. These rates are very similar to those measured in previous myosin movement assays. The rates of movement are relatively independent of the type of actin used. The filament velocity shows a broad pH optimum of 7.0-9.0, and the concn. of ATP required for half-maximal velocity is 50 μM. Apparently, movement of actin over myosin requires at most the no. of heads in a single thick filament. This system provides a practical, quant. myosin-movement assay with purified proteins.
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    Winkelmann, D. A.; Bourdieu, L.; Ott, A.; Kinose, F.; Libchaber, A. Flexibility of myosin attachment to surfaces influences F-actin motion. Biophys. J. 1995, 68, 2444– 2453,  DOI: 10.1016/S0006-3495(95)80426-1
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    Flexibility of myosin attachment to surfaces influences F-actin motion
    Winkelmann, Donald A.; Bourdieu, Laurent; Ott, Albrecht; Kinose, Fumi; Libchaber, Albert
    Biophysical Journal (1995), 68 (6), 2444-53CODEN: BIOJAU; ISSN:0006-3495. (Biophysical Society)
    We have analyzed the dependence of actin filament sliding movement on the mode of myosin attachment to surfaces. Monoclonal antibodies (mAbs) that bind to three distinct sites were used to tether myosin to nitrocellulsoe-coated glass. One antibody reacts with an epitope on the regulatory light chain (LC2) located at the head-rod junction. The other two react with sites in the rod domain, one in the S2 region near the S2-LMM hinge, and the other at the C terminus of the myosin rod. This method of attachment provides a means of controlling the flexibility and d. of myosin on the surface. Fast skeletal muscle myosin monomers were bound to the surfaces through the specific interaction with these mAbs, and the sliding movement of fluorescently labeled actin filaments was analyzed by video microscopy. Each of these antibodies produced stable myosin-coated surface that supported uniform motion of actin over the course of several hours. Attachment of myosin through the anti-S2 and anti-LMM mAbs yielded significantly higher velocities (10 μm/s at 30°C) than attachment through anti-LC2 (4-5 μm/s at 30°C). For each antibody, we obsd. a characteristic value of the myosin d. for the onset of F-actin motion and a second crit. d. for velocity satn. The specific mode of attachment influences the velocity of actin filaments and the characteristic surface d. needed to support movement.
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  18. 18
    Harada, Y.; Noguchi, A.; Kishino, A.; Yanagida, T. Sliding movement of single actin filaments on one-headed myosin filaments. Nature 1987, 326, 805,  DOI: 10.1038/326805a0
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    18
    Sliding movement of single actin filaments on one-headed myosin filaments
    Harada, Yoshie; Noguchi, Akira; Kishino, Akiyoshi; Yanagida, Toshio
    Nature (London, United Kingdom) (1987), 326 (6115), 805-8CODEN: NATUAS; ISSN:0028-0836.
    The myosin mol. consists of 2 heads, each of which contain an enzymic active site and an actin-binding site. The fundamental problem of whether the 2 heads function independently or cooperatively during muscle contraction was studied by an assay system in which sliding movements of fluorescently labeled, single actin filaments along myosin filaments can be obsd. directly. Direct measurement of the sliding of single actin filaments along 1-headed myosin filaments are reported in which the d. of heads was varied over a wide range. The results show that cooperative interaction between the 2 heads of myosin is not essential for inducing the sliding movement of actin filaments.
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  19. 19
    Månsson, A.; Balaz, M.; Albet-Torres, N.; Johan Rosengren, K. In vitro assays of molecular motors – impact of motor-surface interactions. Front. Biosci., Landmark Ed. 2008, 6, 5732,  DOI: 10.2741/3112
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    Howard, J.; Hudspeth, A. J.; Vale, R. D. Movement of microtubules by single kinesin molecules. Nature 1989, 342, 154– 158,  DOI: 10.1038/342154a0
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    Movement of microtubules by single kinesin molecules
    Howard, J.; Hudspeth, A. J.; Vale, R. D.
    Nature (London, United Kingdom) (1989), 342 (6246), 154-8CODEN: NATUAS; ISSN:0028-0836.
    Kinesin is a motor protein that uses energy derived from ATP hydrolysis to move organelles along microtubules. A technique based on dark-field microscopy is described for measuring the movement produced in vitro by individual kinesin mols. It is shown that a single kinesin mol. can move a microtubule for several micrometers. New information about the mechanism of force generation by kinesin is presented.
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  21. 21
    Kotani, N.; Sakakibara, H.; Burgess, S. A.; Kojima, H.; Oiwa, K. Mechanical properties of inner-arm dynein-f (dynein I1) studied with in vitro motility assays. Biophys. J. 2007, 93, 886– 894,  DOI: 10.1529/biophysj.106.101964
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    21
    Mechanical properties of inner-arm dynein-F (dynein I1) studied with in vitro motility assays
    Kotani, Norito; Sakakibara, Hitoshi; Burgess, Stan A.; Kojima, Hiroaki; Oiwa, Kazuhiro
    Biophysical Journal (2007), 93 (3), 886-894CODEN: BIOJAU; ISSN:0006-3495. (Biophysical Society)
    Inner-arm dynein-f of Chlamydomonas flagella is a heterodimeric dynein. We performed conventional in vitro motility assays showing that dynein-f translocates microtubules at the comparatively low velocity of ∼1.2 μm/s. From the dependence of velocity upon the surface d. of dynein-f, we est. its duty ratio to be 0.6-0.7. The relation between microtubule landing rate and surface d. of dynein-f are well fitted by the first-power dependence, as expected for a processive motor. At low dynein densities, progressing microtubules rotate erratically about a fixed point on the surface, at which a single dynein-f mol. is presumably located. We conclude that dynein-f has high processivity. In an axoneme, however, slow and processive dynein-f could impede microtubule sliding driven by other fast dyneins (e.g., dynein-c). To obtain insight into the in vivo roles of dynein-f, we measured the sliding velocity of microtubules driven by a mixt. of dyneins -c and -f at various mixing ratios. The velocity is modulated as a function of the ratio of dynein-f in the mixt. This modulation suggests that dynein-f acts as a load in the axoneme, but force pushing dynein-f mols. forward seems to accelerate their dissocn. from microtubules.
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  22. 22
    Wang, M. D.; Schnitzer, M. J.; Yin, H.; Landick, R.; Gelles, J.; Block, S. V. Force and Velocity Measured for Single Molecules of RNA Polymerase. Science (80-.). 1998, 282, 902– 907
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    22
    Force and velocity measured for single molecules of RNA polymerase
    Wang, Michelle D.; Schmitzer, Mark J.; Yin, Hong; Landic, Robert; Gelles, Jeff; Block, Steven M.
    Science (Washington, D. C.) (1998), 282 (5390), 902-907CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
    RNA polymerase (RNAP) moves along DNA while carrying out transcription, acting as a mol. motor. Transcriptional velocities for single mols. of Escherichia coli RNAP were measured as progressively larger forces were applied by a feedback-controlled optical trap. The shapes of RNAP force-velocity curves are distinct from those of the motor enzymes myosin or kinesin, and indicate that biochem. steps limiting transcription rates at low loads do not generate movement. Modeling the data suggests that high loads may halt RNAP by promoting a structural change which moves all or part of the enzyme backwards through a comparatively large distance, corresponding to 5 to 10 base pairs. This contrasts with previous models that assumed force acts directly upon a single-base translocation step.
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  23. 23
    Bachand, G. D.; Rivera, S. B.; Carroll-Portillo, A.; Hess, H.; Bachand, M. Active capture and transport of virus particles using a biomolecular motor-driven, nanoscale antibody sandwich assay. Small 2006, 2, 381,  DOI: 10.1002/smll.200500262
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    23
    Active capture and transport of virus particles using a biomolecular motor-driven, nanoscale antibody sandwich assay
    Bachand, George D.; Rivera, Susan B.; Carroll-Portillo, Amanda; Hess, Henry; Bachand, Marlene
    Small (2006), 2 (3), 381-385CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)
    Virus particles are captured and transported using kinesin-driven, antibody-functionalized microtubules. The functionalization was achieved through covalent crosslinking, which consequently enhanced the microtubule stability. The capture and transport of the virus particles was subsequently demonstrated in gliding motility assays in which antibody-coated microtubules functioned as capture elements, and antibody-coated microspheres served as fluorescent reporters (see Figure).
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  24. 24
    Hess, H. Engineering Applications of Biomolecular Motors. Annu. Rev. Biomed. Eng. 2011, 13, 429– 450,  DOI: 10.1146/annurev-bioeng-071910-124644
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    24
    Engineering applications of biomolecular motors
    Hess, Henry
    Annual Review of Biomedical Engineering (2011), 13 (), 429-450CODEN: ARBEF7; ISSN:1523-9829. (Annual Reviews Inc.)
    A review. Biomol. motors, in particular motor proteins from the kinesin and myosin families, can be used to explore engineering applications of mol. motors in general. Their outstanding performance enables the exptl. study of hybrid systems, where bio-inspired functions such as sensing, actuation, and transport rely on the nanoscale generation of mech. force. Scaling laws and theor. studies demonstrate the optimality of biomol. motor designs and inform the development of synthetic mol. motors.
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  25. 25
    Kumar, S.; Månsson, A. Covalent and non-covalent chemical engineering of actin for biotechnological applications. Biotechnol. Adv. 2017, 35, 867– 888,  DOI: 10.1016/j.biotechadv.2017.08.002
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    25
    Covalent and non-covalent chemical engineering of actin for biotechnological applications
    Kumar, Saroj; Mansson, Alf
    Biotechnology Advances (2017), 35 (7), 867-888CODEN: BIADDD; ISSN:0734-9750. (Elsevier)
    The cytoskeletal filaments are self-assembled protein polymers with 8-25 nm diams. and up to several tens of micrometres length. They have a range of pivotal roles in eukaryotic cells, including transportation of intracellular cargoes (primarily microtubules with dynein and kinesin motors) and cell motility (primarily actin and myosin) where muscle contraction is one example. For two decades, the cytoskeletal filaments and their assocd. motor systems have been explored for nanotechnol. applications including miniaturized sensor systems and lab-on-a-chip devices. Several developments have also revolved around possible exploitation of the filaments alone without their motor partners. Efforts to use the cytoskeletal filaments for applications often require chem. or genetic engineering of the filaments such as specific conjugation with fluorophores, antibodies, oligonucleotides or various macromol. complexes e.g. nanoparticles. Similar conjugation methods are also instrumental for a range of fundamental biophys. studies. Here we review methods for non-covalent and covalent chem. modifications of actin filaments with focus on crit. advantages and challenges of different methods as well as crit. steps in the conjugation procedures. We also review potential uses of the engineered actin filaments in nanotechnol. applications and in some key fundamental studies of actin and myosin function. Finally, we consider possible future lines of investigation that may be addressed by applying chem. conjugation of actin in new ways.
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  26. 26
    Kumar, S.; ten Siethoff, L.; Persson, M.; Lard, M.; te Kronnie, G.; Linke, H.; Månsson, A. Antibodies covalently immobilized on actin filaments for fast myosin driven analyte transport. PLoS One 2012, 7, e46298,  DOI: 10.1371/journal.pone.0046298
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    26
    Antibodies covalently immobilized on actin filaments for fast myosin driven analyte transport
    Kumar, Saroj; ten Siethoff, Lasse; Persson, Malin; Lard, Mercy; te Kronnie, Geertruy; Linke, Heiner; Maansson, Alf
    PLoS One (2012), 7 (10), e46298CODEN: POLNCL; ISSN:1932-6203. (Public Library of Science)
    Biosensors would benefit from further miniaturization, increased detection rate and independence from external pumps and other bulky equipment. Whereas transportation systems built around mol. motors and cytoskeletal filaments hold significant promise in the latter regard, recent proof-of-principle devices based on the microtubule-kinesin motor system have not matched the speed of existing methods. An attractive soln. to overcome this limitation would be the use of myosin driven propulsion of actin filaments which offers motility one order of magnitude faster than the kinesin-microtubule system. Here, we realized a necessary requirement for the use of the actomyosin system in biosensing devices, namely covalent attachment of antibodies to actin filaments using heterobifunctional cross-linkers. We also demonstrated consistent and rapid myosin II driven transport where velocity and the fraction of motile actin filaments was negligibly affected by the presence of antibody-antigen complexes at rather high d. (>20 μm-1). The results, however, also demonstrated that it was challenging to consistently achieve high d. of functional antibodies along the actin filament, and optimization of the covalent coupling procedure to increase labeling d. should be a major focus for future work. Despite the remaining challenges, the reported advances are important steps towards considerably faster nanosepn. than shown for previous mol. motor based devices, and enhanced miniaturization because of high bending flexibility of actin filaments.
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  27. 27
    Kumar, S.; Milani, G.; Takatsuki, H.; Lana, T.; Persson, M.; Frasson, C.; te Kronnie, G.; Månsson, A. Sensing protein antigen and microvesicle analytes using high-capacity biopolymer nano-carriers. Analyst 2016, 141, 836– 846,  DOI: 10.1039/C5AN02377G
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    27
    Sensing protein antigen and microvesicle analytes using high-capacity biopolymer nano-carriers
    Kumar, Saroj; Milani, Gloria; Takatsuki, Hideyo; Lana, Tobia; Persson, Malin; Frasson, Chiara; te Kronnie, Geertruy; Maansson, Alf
    Analyst (Cambridge, United Kingdom) (2016), 141 (3), 836-846CODEN: ANALAO; ISSN:0003-2654. (Royal Society of Chemistry)
    Lab-on-a-chip systems with mol. motor driven transport of analytes attached to cytoskeletal filament shuttles (actin filaments, microtubules) circumvent challenges with nanoscale liq. transport. However, the filaments have limited cargo-carrying capacity and limitations either in transportation speed (microtubules) or control over motility direction (actin). To overcome these constraints the authors here report incorporation of covalently attached antibodies into self-propelled actin bundles (nanocarriers) formed by crosslinking antibody conjugated actin filaments via fascin, a natural actin-bundling protein. The authors demonstrate high max. antigen binding activity and propulsion by surface adsorbed myosin motors. Analyte transport capacity is tested using both protein antigens and microvesicles, a novel class of diagnostic markers. Increased incubation concn. with protein antigen in the 0.1-100 nM range (1 min) reduces the fraction of motile bundles and their velocity but max. transportation capacity of >1 antigen per nm of bundle length is feasible. At sub-nanomolar protein analyte concn., motility is very well preserved opening for orders of magnitude improved limit of detection using motor driven concn. on nanoscale sensors. Microvesicle-complexing to monoclonal antibodies on the nanocarriers compromises motility but nanocarrier aggregation via microvesicles shows unique potential in label-free detection with the aggregates themselves as non-toxic reporter elements.
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  28. 28
    Korten, T.; Chaudhuri, S.; Tavkin, E.; Braun, M.; Diez, S. Kinesin-1 Expressed in Insect Cells Improves Microtubule in Vitro Gliding Performance, Long-Term Stability and Guiding Efficiency in Nanostructures. IEEE Trans. Nanobioscience 2016, 15, 62– 69,  DOI: 10.1109/TNB.2016.2520832
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    28
    Kinesin-1 Expressed in Insect Cells Improves Microtubule in Vitro Gliding Performance, Long-Term Stability and Guiding Efficiency in Nanostructures
    Korten Till; Chaudhuri Samata; Tavkin Elena; Braun Marcus; Diez Stefan
    IEEE transactions on nanobioscience (2016), 15 (1), 62-9 ISSN:.
    The cytoskeletal motor protein kinesin-1 has been successfully used for many nanotechnological applications. Most commonly, these applications use a gliding assay geometry where substrate-attached motor proteins propel microtubules along the surface. So far, this assay has only been shown to run undisturbed for up to 8 h. Longer run times cause problems like microtubule shrinkage, microtubules getting stuck and slowing down. This is particularly problematic in nanofabricated structures where the total number of microtubules is limited and detachment at the structure walls causes additional microtubule loss. We found that many of the observed problems are caused by the bacterial expression system, which has so far been used for nanotechnological applications of kinesin-1. We strive to enable the use of this motor system for more challenging nanotechnological applications where long-term stability and/or reliable guiding in nanostructures is required. Therefore, we established the expression and purification of kinesin-1 in insect cells which results in improved purity and--more importantly--long-term stability > 24 h and guiding efficiencies of > 90% in lithographically defined nanostructures.
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  29. 29
    Korten, T.; Månsson, A.; Diez, S. Towards the Application of Cytoskeletal Motor Proteins in Molecular Detection and Diagnostic Devices. Curr. Opin. Biotechnol. 2010, 21, 477,  DOI: 10.1016/j.copbio.2010.05.001
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    Towards the application of cytoskeletal motor proteins in molecular detection and diagnostic devices
    Korten, Till; Mansson, Alf; Diez, Stefan
    Current Opinion in Biotechnology (2010), 21 (4), 477-488CODEN: CUOBE3; ISSN:0958-1669. (Elsevier B.V.)
    A review. Over the past ten years, great advancements have been made towards using biomol. motors for nanotechnol. applications. In particular, devices using cytoskeletal motor proteins for mol. transport are maturing. First efforts towards designing such devices used motor proteins attached to micro-structured substrates for the directed transport of microtubules and actin filaments. Soon thereafter, the specific capture, transport and detection of target analytes like viruses were demonstrated. Recently, spatial guiding of the gliding filaments was added to increase the sensitivity of detection and allow parallelization. Whereas mol. motor powered devices have not yet demonstrated performance beyond the level of existing detection techniques, the potential is great: Replacing microfluidics with transport powered by mol. motors allows integration of the energy source (ATP) into the assay soln. This opens up the opportunity to design highly integrated, miniaturized, autonomous detection devices. Such devices, in turn, may allow fast and cheap on-site diagnosis of diseases and detection of environmental pathogens and toxins.
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  30. 30
    Bachand, G. D.; Hess, H.; Ratna, B.; Satir, P.; Vogel, V. Smart dust” biosensors powered by biomolecular motors. Lab Chip 2009, 9, 1661– 1666,  DOI: 10.1039/b821055a
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    "Smart dust" biosensors powered by biomolecular motors
    Bachand, George D.; Hess, Henry; Ratna, Banahalli; Satir, Peter; Vogel, Viola
    Lab on a Chip (2009), 9 (12), 1661-1666CODEN: LCAHAM; ISSN:1473-0197. (Royal Society of Chemistry)
    The concept of a microfabricated biosensor for environmental and biomedical monitoring applications which is composed of environmentally benign components is presented. With a built-in power source (the biol. fuel ATP) and driven by biol. motors (kinesin), sensing in the microdevice can be remotely activated and the presence of a target mol. or toxin remotely detected. The multifaceted progress towards the realization of such a device is described.
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  31. 31
    Nicolau, D. V., Jr.; Lard, M.; Korten, T.; van Delft, F. C. M. J. M.; Persson, M.; Bengtsson, E.; Månsson, A.; Diez, S.; Linke, H.; Nicolau, D. V. Parallel computation with molecular-motor-propelled agents in nanofabricated networks. Proc. Natl. Acad. Sci. U. S. A. 2016, 113, 2591– 2596,  DOI: 10.1073/pnas.1510825113
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    Parallel computation with molecular-motor-propelled agents in nanofabricated networks
    Nicolau, Dan V., Jr.; Lard, Mercy; Korten, Till; van Delft, Falco C. M. J. M.; Persson, Malin; Bengtsson, Elina; Mansson, Alf; Diez, Stefan; Linke, Heiner; Nicolau, Dan V.
    Proceedings of the National Academy of Sciences of the United States of America (2016), 113 (10), 2591-2596CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
    The combinatorial nature of many important math. problems, including nondeterministic-polynomial-time (NP)-complete problems, places a severe limitation on the problem size that can be solved with conventional, sequentially operating electronic computers. There have been significant efforts in conceiving parallel-computation approaches in the past, for example: DNA computation, quantum computation, and microfluidics-based computation. However, these approaches have not proven, so far, to be scalable and practical from a fabrication and operational perspective. Here, we report the foundations of an alternative parallel-computation system in which a given combinatorial problem is encoded into a graphical, modular network that is embedded in a nanofabricated planar device. Exploring the network in a parallel fashion using a large no. of independent, mol.-motor-propelled agents then solves the math. problem. This approach uses orders of magnitude less energy than conventional computers, thus addressing issues related to power consumption and heat dissipation. We provide a proof-of-concept demonstration of such a device by solving, in a parallel fashion, the small instance {2, 5, 9} of the subset sum problem, which is a benchmark NP-complete problem. Finally, we discuss the tech. advances necessary to make our system scalable with presently available technol.
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    Bunk, R.; Klinth, J.; Montelius, L.; Nicholls, I. A.; Omling, P.; Tågerud, S.; Månsson, A. Actomyosin motility on nanostructured surfaces. Biochem. Biophys. Res. Commun. 2003, 301, 783– 788,  DOI: 10.1016/S0006-291X(03)00027-5
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    Actomyosin motility on nanostructured surfaces
    Bunk, Richard; Klinth, Jeanna; Montelius, Lars; Nicholls, Ian A.; Omling, Par; Tagerud, Sven; Mansson, Alf
    Biochemical and Biophysical Research Communications (2003), 301 (3), 783-788CODEN: BBRCA9; ISSN:0006-291X. (Elsevier Science)
    We have here, for the first time, used nanofabrication techniques to reproduce aspects of the ordered actomyosin arrangement in a muscle cell. The adsorption of functional heavy meromyosin (HMM) to five different resist polymers was first assessed. One group of resists (MRL-6000.1XP and ZEP-520) consistently exhibited high quality motility of actin filaments after incubation with HMM. A second group (PMMA-200, PMMA-950, and MRI-9030) generally gave low quality of motility with only few smoothly moving filaments. Based on these findings electron beam lithog. was applied to a bilayer resist system with PMMA-950 on top of MRL-6000.1XP. Grooves (100-200 nm wide) in the PMMA layer were created to expose the MRL-6000.1XP surface for adsorption of HMM and guidance of actin filament motility. This guidance was quite efficient allowing no U-turns of the filaments and approx. 20 times higher d. of moving filaments in the grooves than on the surrounding PMMA.
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    Månsson, A. Translational actomyosin research: fundamental insights and applications hand in hand. J. Muscle Res. Cell Motil. 2012, 33, 219,  DOI: 10.1007/s10974-012-9298-5
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    Translational actomyosin research: fundamental insights and applications hand in hand
    Mansson, Alf
    Journal of Muscle Research and Cell Motility (2012), 33 (3-4), 219-233CODEN: JMRMD3; ISSN:0142-4319. (Springer)
    This review describes the development towards actomyosin based nanodevices taking a starting point in pioneering studies in the 1990s based on conventional in vitro motility assays. Refs. are given to parallel developments using the kinesin-microtubule motor system. The early developments focused on achieving cargo-transportation using actin filaments as cargo-loaded shuttles propelled by surface-adsorbed heavy meromyosin along micro- and nanofabricated channels. These efforts prompted extensive studies of surface-motor interactions contributing with new insights of general relevance in surface and colloid chem. As a result of these early efforts, a range of complex devices have now emerged, spanning applications in medical diagnostics, biocomputation and formation of complex nanostructures by self-organization. In addn. to giving a comprehensive account of the developments towards real-world applications an important goal of the present review is to demonstrate important connections between the applied studies and fundamental biophys. studies of actomyosin and muscle function. Thus the manipulation of the motor proteins towards applications has resulted in new insights into methodol. aspects of the in vitro motiliy assay. Other developments have advanced the understanding of the dynamic materials properties of actin filaments.
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    Agarwal, A.; Hess, H. Biomolecular motors at the intersection of nanotechnology and polymer science. Prog. Polym. Sci. 2010, 35, 252,  DOI: 10.1016/j.progpolymsci.2009.10.007
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    Biomolecular motors at the intersection of nanotechnology and polymer science
    Agarwal, Ashutosh; Hess, Henry
    Progress in Polymer Science (2010), 35 (1-2), 252-277CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)
    A review. The dynamic cytoskeletal components, biomol. motors and their assocd. filaments, can be integrated in vitro with synthetic components to enable nanoscale transport systems. These "mol. shuttles" have generated significant scientific interest over the past decade, resulting in over 200 publications. This review focuses on the contributions involving the use of linear biomol. motors, kinesin and myosin, and their assocd. filaments, microtubule and actin, in device applications. Exploiting the naturally occurring motion between the motors and their assocd. filaments requires an interdisciplinary understanding of the underlying challenges. Three basic topics that most of the exptl. contributions have sought to address are: the guiding of shuttle movement, the loading and unloading of cargo onto the shuttles, and the control of motor activity. The phys. properties of motors and filaments det. the engineering solns. to the design challenges. The applications, which center on the basic capability of nanoscale motion, and the roadblocks to their widespread implementation will be discussed in detail.
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    Agarwal, A.; Hess, H. Molecular Motors as Components of Future Medical Devices and Engineered Materials. J. Nanotechnol. Eng. Med. 2009, 1, 11005– 11009,  DOI: 10.1115/1.3212823
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    A general regeneration, identification, and optimization (RO) protocol for Biacore systems was developed. The RO protocol uses six multi-ingredient stock solns. that represent the six most common chem. properties employed as regeneration agents. The regeneration effect of different regeneration cocktails of these six stock solns. were tested iteratively until a satisfactory result was obtained. The RO protocol was designed with an ease-of-use and multivariate approach. The RO protocol was tested on 13 different antibody-antigen systems. For 10 of these, only the first screening session was tested. For 9 of the 13 systems, the RO-protocol screening session identified cocktails that removed more than 90% of the bound analyte in a 30 s pulse. For 5 systems, the RO protocol identified cocktails that regenerated the surface completely and that were more gentle than previously used regeneration conditions. Furthermore, the regeneration optimization results can be interpreted as a characterization of the interacting mols. The relevance of testing cocktails was justified by the fact that at least one cocktail was significantly better than all dild. stock solns. for all tested model systems. By using the multivariate approach, the risk of missing relevant combinations of stock solns. was minimized. This resulted in an unexpected discovery of excellent properties of EDTA as an additive in regeneration cocktails contg. chaotropic agents and ions in high concn.
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    Selective Spatial Localization of Actomyosin Motor Function by Chemical Surface Patterning
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    Langmuir (2006), 22 (17), 7302-7312CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
    We have previously described the efficient guidance and unidirectional sliding of actin filaments along nanosized tracks with adsorbed heavy meromyosin (HMM; myosin II motor fragment). In those expts., the tracks were functionalized with trimethylchlorosilane (TMCS) by chem. vapor deposition (CVD) and surrounded by hydrophilic areas. Here we first show, using in vitro motility assays on nonpatterned and micropatterned surfaces, that the quality of HMM function on CVD-TMCS is equiv. to that on std. nitrocellulose substrates. We further examine the influences of phys. properties of different surfaces (glass, SiO2, and TMCS) and chem. properties of the buffer soln. on motility. With the presence of methylcellulose in the assay soln., there was HMM-induced actin filament sliding on both glass/SiO2 and on TMCS, but the velocity was higher on TMCS. This difference in velocity increased with decreasing contact angles of the glass and SiO2 surfaces in the range of 20-67° (advancing contact angles for water droplets). The corresponding contact angle of CVD-TMCS was 81°. In the absence of methylcellulose, there was high-quality motility on TMCS but no motility on glass/SiO2. This observation was independent of the contact angle of the glass/SiO2 surfaces and of HMM incubation concns. (30-150 μg mL-1) and ionic strengths of the assay soln. (20-50 mM). Complete motility selectivity between TMCS and SiO2 was obsd. for both nonpatterned and for micro- and nanopatterned surfaces. Spectrophotometric anal. of HMM depletion during incubation, K/EDTA ATPase measurements, and total internal reflection fluorescence spectroscopy of HMM binding showed only minor differences in HMM surface densities between TMCS and SiO2/glass. Thus, the motility contrast between the two surface chemistries seems to be attributable to different modes of HMM binding with the hindrance of actin binding on SiO2/glass.
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    For the past 25 years NIH Image and ImageJ software have been pioneers as open tools for the anal. of scientific images. We discuss the origins, challenges and solns. of these two programs, and how their history can serve to advise and inform other software projects.
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    We report on a novel approach for the size-dependent fractionation of protein assemblies on polymeric surfaces. Using a simple temp. gradient method to generate one-dimensional gradients of grafted poly(ethylene glycol), we fabricated silicon-oxide chips with a gradually changing surface d. of kinesin motor mols. We demonstrate that such a bioactive surface can be used to sort gliding microtubules according to their length. To our knowledge, this is the first example of the self-organized sorting of protein assemblies on surfaces.
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    Challenges in Estimating the Motility Parameters of Single Processive Motor Proteins
    Ruhnow, Felix; Kloβ, Linda; Diez, Stefan
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    Cytoskeletal motor proteins are essential to the function of a wide range of intracellular mechano-systems. The biophys. characterization of their movement along their filamentous tracks is therefore of large importance. Toward this end, single-mol., in vitro stepping-motility assays are commonly used to det. motor velocity and run length. However, comparing results from such expts. proved difficult due to influences from variations in the exptl. conditions and the data anal. methods. Here, the authors study the movement of fluorescently labeled, processive, dimeric motor proteins and propose a unified algorithm to correct the measurements for finite filament length as well as photobleaching. Particular emphasis is put on estg. the statistical errors assocd. with the proposed evaluation method, as knowledge of these values is crucial when comparing measurements from different expts. Testing the authors' approach with simulated and exptl. data from GFP-labeled kinesin-1 motors stepping along immobilized microtubules, the authors show (1) that velocity distributions should be fitted by a t location-scale probability d. function rather than by a normal distribution; (2) that the impossibility to measure events shorter than the image acquisition time needs to be taken into account; (3) that the interaction time and run length of the motors can be estd. independent of the filament length distribution; and (4) that the dimeric nature of the motors needs to be considered when correcting for photobleaching. Moreover, the authors' anal. reveals that controlling the temp. during the expts. with a precision <1 K is of importance. The authors believe the authors' method will not only improve the evaluation of exptl. data, but also allow for better statistical comparisons between different populations of motor proteins (e.g., with distinct mutations or linked to different cargos) and filaments (e.g., in distinct nucleotide states or with different posttranslational modifications). Therefore, the authors include a detailed workflow for image processing and anal. (including MATLAB code), serving as a tutorial for the estn. of motility parameters in stepping-motility assays.
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    Nano Letters (2005), 5 (6), 1117-1122CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    The authors demonstrate highly efficient rectification of microtubule motility on gold nanofabricated structures. First, the authors present a novel nanofabrication process for the creation of gold tracks for microtubule motility recessed in silicon oxide. This approach is particularly useful because it enables the use of the well-understood PEG-silane chem. on SiO2 for the blocking of kinesin, whereas the gold tracks allow possible elec. control. The authors demonstrate excellent confinement of microtubule motility to the gold nanostructures and that microtubules move on the gold with speeds comparable to that on glass. Second, the authors present designs of three advanced rectifier geometries. The authors analyze the microtubule pathways through the geometries, and the authors demonstrate highly efficient rectification with up to 92% efficiency. As a result, the authors find that up to 97% of the microtubules move unidirectionally.
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    Lindberg, F. W.; Norrby, M.; Rahman, M. A.; Salhotra, A.; Takatsuki, H.; Jeppesen, S.; Linke, H.; Månsson, A. Controlled Surface Silanization for actin–myosin Based Nanodevices and Biocompatibility of New Polymer Resists. Langmuir 2018, 34, 8777– 8784,  DOI: 10.1021/acs.langmuir.8b01415
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    Controlled Surface Silanization for Actin-Myosin Based Nanodevices and Biocompatibility of New Polymer Resists
    Lindberg, Frida W.; Norrby, Marlene; Rahman, Mohammad A.; Salhotra, Aseem; Takatsuki, Hideyo; Jeppesen, Soeren; Linke, Heiner; Maansson, Alf
    Langmuir (2018), 34 (30), 8777-8784CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
    Mol. motor-based nanodevices require organized cytoskeletal filament guiding along motility-promoting tracks, confined by motility-inhibiting walls. One way to enhance motility quality on the tracks, particularly in terms of filament velocity but also the fraction of motile filaments, is to optimize the surface hydrophobicity. The authors have studied the potential to achieve this for the actin-myosin II motor system on trimethylchlorosilane (TMCS)-derivatized SiO2 surfaces to be used as channel floors in nanodevices. The authors have also studied the ability to suppress motility on two new polymer resists, TU7 (for nanoimprint lithog.) and CSAR 62 (for electron beam and deep UV lithog.), to be used as channel walls. The authors developed a CVD tool for silanizing SiO2 surfaces in a controlled environment to achieve different surface hydrophobicities (measured by water contact angle). In contrast to previous work, the authors were able to fabricate a wide range of contact angles by varying the silanization time and chamber pressure using only one type of silane. This resulted in a significant improvement of the silanization procedure, producing a predictable contact angle on the surface and thereby predictable quality of the heavy meromyosin (HMM)-driven actin motility with regard to velocity. The authors obsd. a high degree of correlation between the filament sliding velocity and contact angle in the range 10-86°, expanding the previously studied range. The sliding velocity on TU7 surfaces was superior to that on CSAR 62 surfaces despite similar contact angles. In addn., the authors were able to suppress the motility on both TU7 and CSAR 62 by plasma oxygen treatment before silanization. These results are discussed in relation to previously proposed surface adsorption mechanisms of HMM and their relation to the water contact angle. Addnl., the results are considered for the development of actin-myosin based nanodevices with superior performance with respect to actin-myosin functionality.
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  12. Jingyuan Zhu, Till Korten, Hillel Kugler, Falco van Delft, Alf Månsson, Danny Reuter, Stefan Diez, Heiner Linke. Physical requirements for scaling up network-based biocomputation. New Journal of Physics 2021, 23 (10) , 105004. https://doi.org/10.1088/1367-2630/ac2a5d
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  15. Qingliang Yang, Ying Gao, Lei Xu, Weiyong Hong, Yuanbin She, Gensheng Yang. Enzyme-driven micro/nanomotors: Recent advances and biomedical applications. International Journal of Biological Macromolecules 2021, 167 , 457-469. https://doi.org/10.1016/j.ijbiomac.2020.11.215
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Cite this: Nano Lett. 2019, 19, 10, 7155–7163
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  • Abstract

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    Figure 1

    Figure 1. Optimized method for regeneration of molecular-motor-based nano/microdevices. (a). After performing an in vitro motility assay (left panel), the main steps of the regeneration process (right panel) are (i) incubation with proteinase K (200 μg/mL; preactivated by Ca) for 1 h at 37 °C to digest the surface-adhered proteins, followed by (ii) incubation with PMSF (5 mM) for 5 min at room temperature (RT) to inactivate any remaining proteinase K, and (iii) incubation with SDS (5%) or Triton X100 (0.05%) for 5 min at room temperature to remove protein fragments from the surface. Afterward, fresh proteins can be added for new motility assays. Inset photos: Coomassie brilliant blue stain (0.1%) of the flow cell before addition of HMM or any other component (control), immediately after incubation with HMM at surface-saturating concentration (120 μg/mL) and after steps (i) and (iii) of the regeneration process. (b) Flow-cell opacity (average intensity measured from region of interest (ROI) in flow cell area subtracted by the average intensity in similar ROI on the glass outside the flow cell). Data from two experiments using Triton X100 (0.05%) as detergent (given ± pixel standard error of the mean) normalized to control value. See SI for details.

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    Figure 2

    Figure 2. Gliding motility assays before and after regeneration. (a,c) Fluorescence micrographs zooming in on five gliding actin filaments on an HMM-coated, TMCS-derivatized SiO2 surface before (a) and after (c) regeneration. The images show maximum projections (derived using ImageJ (46)) of time-lapse movies from time 0 s to the time points indicated. Actin filament positions at the latter time point are highlighted. (b,d) Maximum projections (from 4 s time-lapse movies at lower magnification) of gliding actin filaments before (b) and after (d) regeneration. (e,g) Fluorescence micrographs zooming in on few microtubules gliding on kinesin-coated glass substrates before (e) and after (g) regeneration. Again, the images show maximum projections of time-lapse movies from time 0 s to the time points indicated. Microtubule positions at the latter time point are highlighted. (f,h) Maximum projections (from 121 s time-lapse movies at lower magnification) of gliding microtubules before (f) and after (h) regeneration. Note that the time between frames for HMM-propelled actin filaments is appreciably shorter than for kinesin-propelled microtubules due to higher velocity. Also, the gliding paths are appreciably more curved for the actin filaments due to >10-fold lower persistence length than for microtubules. See Movies S1, S2, S3, and S4 for videos corresponding to data in this figure.

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    Figure 3

    Figure 3. Analysis of motility performance after regeneration. (a) Actin gliding velocity at 25.1–26 °C produced by HMM adsorbed to TMCS-derivatized SiO2 surfaces; “Surface 1” and “Surface 2” represent two different surfaces tested in two different experiments and were regenerated either once (no further regeneration was attempted intentionally) or three times. In each individual experiment, 10–24 actin filaments were analyzed. (b) Actin filament length distribution for filaments propelled by myosin adsorbed to one TMCS-derivatized SiO2 surface before and after each of three regeneration cycles for “Surface 2” in (a). (c) Average microtubule gliding velocity at 25 °C in a kinesin motility assay on glass surfaces. The control value shown is the mean gliding velocity of surfaces 1–3 before regeneration. Surface 1 was regenerated directly after the control gliding assay and was tested without letting the channel dry in between. Surface 2 was processed similarly but the channel was dried before the regeneration procedure. Finally, surface 3 was regenerated and dried afterward before performing a new gliding assay. Subsequently, surface 3 was regenerated a second time (drying before regeneration) and a third time (without drying). In each individual experiment, the velocity of 277–731 microtubules was analyzed. (d) Microtubule length distribution and median length of the assays depicted in (c). The control bar represents an assay before regeneration. Velocity data are given as mean ±95% confidence interval.

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    Figure 4

    Figure 4. Regeneration of an assembled nano/microdevice with embedded microstructures for the microtubule–kinesin system. (a) Schematic cross-section of a microstructured SiO2 surface used for regeneration. On these surfaces, motility was restricted to the gold layers on the patterned, gold-coated floor. The rest of the surface was rendered protein-repellent by a PEG coating. (b) Maximum projections (from 10 min time-lapse movies) of fluorescently labeled microtubules gliding on kinesin-coated gold floors before (“Control”) and after regeneration. (c) Microtubule gliding velocity at different time points before and after regeneration; N = 3 surfaces. At each individual time point, 637–1216 microtubules were analyzed. Data are given as mean ±95% confidence interval. (d) Time series of fluorescence micrographs showing microtubule gliding within one “petal” of the flower structure as depicted in (b) before and after regeneration. The positions of three microtubules are marked along with their trajectories. (e) Average projections as well as maximum projections of fluorescently labeled microtubules gliding within 1 μm wide channels with kinesin-coated gold floors before (“Control”) and after regeneration. The projections were derived from 30 min time-lapse movies. See also Movies S5 and S6.

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    Figure 5

    Figure 5. Regeneration of an assembled motility device with embedded nano/microstructures for the actin–myosin system applying the detergent Triton X100 (instead of SDS). (a) Schematic design of the structured SiO2 surface used for regeneration with topographically and chemically defined areas. The structure was produced by electron beam lithography to produce CSAR62 polymer walls and surroundings (pink) of trimethylchlorosilane-derivatized-SiO2 channels (blue). HMM motors bind to the TMCS-derivatized floors in a motility-promoting manner, whereas binding to the surrounding CSAR 62 polymer walls is inhibited. (51) The large heart shaped structure acts as a loading zone for the actin filaments with the aim to guide them into the 500 nm wide feedback channel. (b) Maximum projections (from 4 s time-lapse movies) showing actin filament gliding driven by HMM motors adsorbed to TMCS-derivatized SiO2 in the heart-shaped structure before (“Control”) and after regeneration. Feeding filaments into the channels were observed in this particular structure neither before nor after regeneration. Note, filaments floating in solution are seen as quite bright objects (due to relatively stationary position) above areas outside the loading zone in the Control. See also Movies S7 and S8. (c) HMM-propelled actin gliding velocity on TMCS-derivatized SiO2 surfaces; N = 2 surfaces, where the first surface was a flat chip and regenerated twice and the second surface had an embedded nanostructure. On the flat SiO2 chip, 18–25 actin filaments were analyzed and on the heart-shaped structure, 3–12 filaments were analyzed. Temperature 26.0–26.6 °C. Data are given as mean ±95% confidence interval.

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      A review. Biosensor sensitivity and selectivity depend essentially on the properties of the biorecognition elements to be used for analyte binding. Two principally different applications are considered, effects monitoring with biol. components as targets for bioeffective substances, among them endocrine disruptors; and immunochem. anal. employing antibodies as binding proteins for a wide variety of analytes such as pesticides. Genetic engineering provides an elegant way not only for providing unlimited amts. of biorecognition mols. but also for the alteration of existing properties and the supplementation with addnl. functions. Instrumental applications were carried out with the optical sensor BIAcore. The first example deals with the characterization of receptors. For this purpose, the human estrogen receptor α was used. Binding studies were carried out with natural as well as xenoestrogens. An equil. dissocn. const. Kd of 2.3 × 10-10 (M) was derived for 17β-estradiol. A competition assay was performed with a bovine serum albumin (BSA)-17β-estradiol conjugate, immobilized at the optical sensor surface, and the free estrogen. The signals obtained represent estradiol equiv. This format was transferred to a microplate-based enzyme-linked receptor assay. It reached a detection limit of 0.02 μg l-1 17β-estradiol and proved suitable for the detection of natural and synthetic estrogens as well as xenoestrogens in field studies. The second example is targeted at kinetic and affinity measurements of recombinant antibody fragments derived from antibody libraries with s-triazine selectivities. Different strategies for the synthesis of antibody fragment libraries, followed by the selection of specific antibody variants, were examd. An antibody library was derived from a set of B cells. Chain shuffling of the heavy and light chains provided the best binders. An enzyme linked immunosorbent assay (ELISA) was achieved for atrazine with an IC50 of 0.9 μg l-1 and a detection limit of 0.2 μg l-1. The close relations between the optimization of recombinant antibodies by evolutionary strategies and genetic algorithms are considered.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XhtFyrtr0%253D&md5=5ac136f61ec51ae60925589fea187962
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      Sugimoto, K.; Tsuchiya, S.; Omori, M.; Matsuda, R.; Fujio, M.; Kuroda, K.; Okido, M.; Hibi, H. Proteomic analysis of bone proteins adsorbed onto the surface of titanium dioxide. Biochem. Biophys. Reports 2016, 7, 316– 322,  DOI: 10.1016/j.bbrep.2016.07.007
      11
      Proteomic analysis of bone proteins adsorbed onto the surface of titanium dioxide
      Sugimoto Keisuke; Omori Masahiro; Matsuda Ryo; Fujio Masahito; Hibi Hideharu; Tsuchiya Shuhei; Kuroda Kensuke; Okido Masazumi
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      Osseointegration is the structural and functional connection between bone tissues and implants such as titanium dioxide (TiO2). The bone-TiO2 interface is thought to contain proteoglycans. However, exhaustive analysis of the proteins in this layer has not been performed. In this study, we evaluated the bone protein adhered on the surface of TiO2 comprehensively. Pig bone protein was extracted by sequential elutions with guanidine, 0.1 M EDTA, and again with guanidine. The proteins obtained from these extractions were allowed to adhere to an HPLC column packed with TiO2 and were eluted with 0.2 M NaOH. The eluted proteins were identified by LC/MS/MS and included not only proteoglycans but also other proteins such as extracellular matrix proteins, enzymes, and growth factors. Calcium depositions were observed on TiO2 particles incubated with bone proteins, guanidine-extracted proteins adhered to TiO2 displayed significantly high amounts of calcium depositions.
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    12. 12
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      12
      Proteome analysis of the plasma protein layer adsorbed to a rough titanium surface
      Dodo, Cindy Goes; Senna, Plinio Mendes; Custodio, William; Paes Leme, Adriana Franco; Del Bel Cury, Altair Antoninha
      Biofouling (2013), 29 (5), 549-557CODEN: BFOUEC; ISSN:0892-7014. (Taylor & Francis Ltd.)
      In this study a label-free proteomic approach was used to investigate the compn. of the layer of protein adsorbed to rough titanium (Ti) after exposure to human blood plasma. The influence of the protein layer on the surface free energy (SFE) of the Ti was evaluated by contact angle measurements. Ti disks were incubated with blood plasma for 180 min at 37 °C, and the proteins recovered were subjected to liq. chromatog. coupled to tandem mass spectrometry anal. A total of 129 different peptides were identified and assigned to 25 distinct plasma proteins. The most abundant proteins were fibronectin, serum albumin, apolipoprotein A-I, and fibrinogen, comprising 74.54% of the total spectral counts. Moreover, the protein layer increased the SFE of the Ti (p < 0.05). The layer adsorbed to the rough Ti surface was composed mainly of proteins related to cell adhesion, mol. transportation, and coagulation processes, creating a polar and hydrophilic interface for subsequent interactions with host cells.
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    13. 13
      Wong, J. Y.; Kuhl, T. L.; Israelachvili, J. N.; Mullah, N.; Zalipsky, S. Direct Measurement of a Tethered Ligand-Receptor Interaction Potential. Science (Washington, DC, U. S.) 1997, 275, 820,  DOI: 10.1126/science.275.5301.820
      13
      Direct measurement of a tethered ligand-receptor interaction potential
      Wong, Joyce Y.; Kuhl, Tonya L.; Israelachvili, Jacob N.; Mullah, Nasreen; Zalipsky, Samuel
      Science (Washington, D. C.) (1997), 275 (5301), 820-822CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      Many biol. recognition interactions involve ligands and receptors are tethered rather than rigidly bound on a cell surface. A surface forces app. was used to directly measure the force-distance interaction between a polymer-tethered ligand and its receptor. At sepns. near the fully extended tether length, the ligands rapidly lock onto the their binding sites, pulling the ligand and receptor together. The measured interaction potential and its dynamics be modeled with std. theories of polymer and colloidal interactions.
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    14. 14
      Bell, S.; Terentjev, E. M. Specific binding of a polymer chain to a sequence of surface receptors. Sci. Rep. 2017, 7, 17272,  DOI: 10.1038/s41598-017-17581-x
      14
      Specific binding of a polymer chain to a sequence of surface receptors
      Bell Samuel; Terentjev Eugene M
      Scientific reports (2017), 7 (1), 17272 ISSN:.
      This paper considers a biologically relevant question of a Gaussian chain (such as an unfolded protein) binding to a sequence of receptors with matching multiple ligands distributed along the chain. Using the characteristic time for a tethered ligand to bind to a surface receptor, we study the case of multiple binding to a linear sequence of receptors on the surface. The tethered binding time is determined by the entropic barrier for the chain to be stretched sufficiently to reach the distant receptor target, and a restriction on chain conformations near the substrate. Adsorption (multiple-site binding) is shown to be dominated by a simple zipper sequence, only occasionally accelerated by loop formation. However, when the number of receptors increases, a competing rate-limiting process takes over: the center of mass of the remaining free chain has to drift down the line of receptors, which takes longer when the receptors are close and the entropic pulling force is low. As a result, the time for the complete chain adsorption is minimised by a certain optimal number of receptors, depending on the distance to be traversed by the free end, and the chain length.
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    15. 15
      Xu, L.-C.; Bauer, J. W.; Siedlecki, C. A. Proteins, platelets, and blood coagulation at biomaterial interfaces. Colloids Surf., B 2014, 124, 49– 68,  DOI: 10.1016/j.colsurfb.2014.09.040
      15
      Proteins, platelets, and blood coagulation at biomaterial interfaces
      Xu, Li-Chong; Bauer, James W.; Siedlecki, Christopher A.
      Colloids and Surfaces, B: Biointerfaces (2014), 124 (), 49-68CODEN: CSBBEQ; ISSN:0927-7765. (Elsevier B.V.)
      A review. Blood coagulation and platelet adhesion remain major impediments to the use of biomaterials in implantable medical devices. There is still significant controversy and question in the field regarding the role that surfaces play in this process. This manuscript addresses this topic area and reports on state of the art in the field. Particular emphasis is placed on the subject of surface engineering and surface measurements that allow for control and observation of surface-mediated biol. responses in blood and test solns. Appropriate use of surface texturing and chem. patterning methodologies allow for redn. of both blood coagulation and platelet adhesion, and new methods of surface interrogation at high resoln. allow for measurement of the relevant biol. factors.
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    16. 16
      Kron, S. J.; Spudich, J. A. Fluorescent actin filaments move on myosin fixed to a glass surface. Proc. Natl. Acad. Sci. U. S. A. 1986, 83, 6272– 6276,  DOI: 10.1073/pnas.83.17.6272
      16
      Fluorescent actin filaments move on myosin fixed to a glass surface
      Kron, Stephen J.; Spudich, James A.
      Proceedings of the National Academy of Sciences of the United States of America (1986), 83 (17), 6272-6CODEN: PNASA6; ISSN:0027-8424.
      Single actin filaments stabilized with fluorescent phalloidin exhibit ATP-dependent movement on myosin filaments fixed to a surface. At pH 7.4 and 24°, the rates of movement av. 3-4 μm/s with skeletal muscle myosin and 1-2 μm/s with Dictyostelium myosin. These rates are very similar to those measured in previous myosin movement assays. The rates of movement are relatively independent of the type of actin used. The filament velocity shows a broad pH optimum of 7.0-9.0, and the concn. of ATP required for half-maximal velocity is 50 μM. Apparently, movement of actin over myosin requires at most the no. of heads in a single thick filament. This system provides a practical, quant. myosin-movement assay with purified proteins.
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    17. 17
      Winkelmann, D. A.; Bourdieu, L.; Ott, A.; Kinose, F.; Libchaber, A. Flexibility of myosin attachment to surfaces influences F-actin motion. Biophys. J. 1995, 68, 2444– 2453,  DOI: 10.1016/S0006-3495(95)80426-1
      17
      Flexibility of myosin attachment to surfaces influences F-actin motion
      Winkelmann, Donald A.; Bourdieu, Laurent; Ott, Albrecht; Kinose, Fumi; Libchaber, Albert
      Biophysical Journal (1995), 68 (6), 2444-53CODEN: BIOJAU; ISSN:0006-3495. (Biophysical Society)
      We have analyzed the dependence of actin filament sliding movement on the mode of myosin attachment to surfaces. Monoclonal antibodies (mAbs) that bind to three distinct sites were used to tether myosin to nitrocellulsoe-coated glass. One antibody reacts with an epitope on the regulatory light chain (LC2) located at the head-rod junction. The other two react with sites in the rod domain, one in the S2 region near the S2-LMM hinge, and the other at the C terminus of the myosin rod. This method of attachment provides a means of controlling the flexibility and d. of myosin on the surface. Fast skeletal muscle myosin monomers were bound to the surfaces through the specific interaction with these mAbs, and the sliding movement of fluorescently labeled actin filaments was analyzed by video microscopy. Each of these antibodies produced stable myosin-coated surface that supported uniform motion of actin over the course of several hours. Attachment of myosin through the anti-S2 and anti-LMM mAbs yielded significantly higher velocities (10 μm/s at 30°C) than attachment through anti-LC2 (4-5 μm/s at 30°C). For each antibody, we obsd. a characteristic value of the myosin d. for the onset of F-actin motion and a second crit. d. for velocity satn. The specific mode of attachment influences the velocity of actin filaments and the characteristic surface d. needed to support movement.
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    18. 18
      Harada, Y.; Noguchi, A.; Kishino, A.; Yanagida, T. Sliding movement of single actin filaments on one-headed myosin filaments. Nature 1987, 326, 805,  DOI: 10.1038/326805a0
      18
      Sliding movement of single actin filaments on one-headed myosin filaments
      Harada, Yoshie; Noguchi, Akira; Kishino, Akiyoshi; Yanagida, Toshio
      Nature (London, United Kingdom) (1987), 326 (6115), 805-8CODEN: NATUAS; ISSN:0028-0836.
      The myosin mol. consists of 2 heads, each of which contain an enzymic active site and an actin-binding site. The fundamental problem of whether the 2 heads function independently or cooperatively during muscle contraction was studied by an assay system in which sliding movements of fluorescently labeled, single actin filaments along myosin filaments can be obsd. directly. Direct measurement of the sliding of single actin filaments along 1-headed myosin filaments are reported in which the d. of heads was varied over a wide range. The results show that cooperative interaction between the 2 heads of myosin is not essential for inducing the sliding movement of actin filaments.
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    19. 19
      Månsson, A.; Balaz, M.; Albet-Torres, N.; Johan Rosengren, K. In vitro assays of molecular motors – impact of motor-surface interactions. Front. Biosci., Landmark Ed. 2008, 6, 5732,  DOI: 10.2741/3112
      There is no corresponding record for this reference.
    20. 20
      Howard, J.; Hudspeth, A. J.; Vale, R. D. Movement of microtubules by single kinesin molecules. Nature 1989, 342, 154– 158,  DOI: 10.1038/342154a0
      20
      Movement of microtubules by single kinesin molecules
      Howard, J.; Hudspeth, A. J.; Vale, R. D.
      Nature (London, United Kingdom) (1989), 342 (6246), 154-8CODEN: NATUAS; ISSN:0028-0836.
      Kinesin is a motor protein that uses energy derived from ATP hydrolysis to move organelles along microtubules. A technique based on dark-field microscopy is described for measuring the movement produced in vitro by individual kinesin mols. It is shown that a single kinesin mol. can move a microtubule for several micrometers. New information about the mechanism of force generation by kinesin is presented.
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    21. 21
      Kotani, N.; Sakakibara, H.; Burgess, S. A.; Kojima, H.; Oiwa, K. Mechanical properties of inner-arm dynein-f (dynein I1) studied with in vitro motility assays. Biophys. J. 2007, 93, 886– 894,  DOI: 10.1529/biophysj.106.101964
      21
      Mechanical properties of inner-arm dynein-F (dynein I1) studied with in vitro motility assays
      Kotani, Norito; Sakakibara, Hitoshi; Burgess, Stan A.; Kojima, Hiroaki; Oiwa, Kazuhiro
      Biophysical Journal (2007), 93 (3), 886-894CODEN: BIOJAU; ISSN:0006-3495. (Biophysical Society)
      Inner-arm dynein-f of Chlamydomonas flagella is a heterodimeric dynein. We performed conventional in vitro motility assays showing that dynein-f translocates microtubules at the comparatively low velocity of ∼1.2 μm/s. From the dependence of velocity upon the surface d. of dynein-f, we est. its duty ratio to be 0.6-0.7. The relation between microtubule landing rate and surface d. of dynein-f are well fitted by the first-power dependence, as expected for a processive motor. At low dynein densities, progressing microtubules rotate erratically about a fixed point on the surface, at which a single dynein-f mol. is presumably located. We conclude that dynein-f has high processivity. In an axoneme, however, slow and processive dynein-f could impede microtubule sliding driven by other fast dyneins (e.g., dynein-c). To obtain insight into the in vivo roles of dynein-f, we measured the sliding velocity of microtubules driven by a mixt. of dyneins -c and -f at various mixing ratios. The velocity is modulated as a function of the ratio of dynein-f in the mixt. This modulation suggests that dynein-f acts as a load in the axoneme, but force pushing dynein-f mols. forward seems to accelerate their dissocn. from microtubules.
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    22. 22
      Wang, M. D.; Schnitzer, M. J.; Yin, H.; Landick, R.; Gelles, J.; Block, S. V. Force and Velocity Measured for Single Molecules of RNA Polymerase. Science (80-.). 1998, 282, 902– 907
      22
      Force and velocity measured for single molecules of RNA polymerase
      Wang, Michelle D.; Schmitzer, Mark J.; Yin, Hong; Landic, Robert; Gelles, Jeff; Block, Steven M.
      Science (Washington, D. C.) (1998), 282 (5390), 902-907CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      RNA polymerase (RNAP) moves along DNA while carrying out transcription, acting as a mol. motor. Transcriptional velocities for single mols. of Escherichia coli RNAP were measured as progressively larger forces were applied by a feedback-controlled optical trap. The shapes of RNAP force-velocity curves are distinct from those of the motor enzymes myosin or kinesin, and indicate that biochem. steps limiting transcription rates at low loads do not generate movement. Modeling the data suggests that high loads may halt RNAP by promoting a structural change which moves all or part of the enzyme backwards through a comparatively large distance, corresponding to 5 to 10 base pairs. This contrasts with previous models that assumed force acts directly upon a single-base translocation step.
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    23. 23
      Bachand, G. D.; Rivera, S. B.; Carroll-Portillo, A.; Hess, H.; Bachand, M. Active capture and transport of virus particles using a biomolecular motor-driven, nanoscale antibody sandwich assay. Small 2006, 2, 381,  DOI: 10.1002/smll.200500262
      23
      Active capture and transport of virus particles using a biomolecular motor-driven, nanoscale antibody sandwich assay
      Bachand, George D.; Rivera, Susan B.; Carroll-Portillo, Amanda; Hess, Henry; Bachand, Marlene
      Small (2006), 2 (3), 381-385CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Virus particles are captured and transported using kinesin-driven, antibody-functionalized microtubules. The functionalization was achieved through covalent crosslinking, which consequently enhanced the microtubule stability. The capture and transport of the virus particles was subsequently demonstrated in gliding motility assays in which antibody-coated microtubules functioned as capture elements, and antibody-coated microspheres served as fluorescent reporters (see Figure).
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    24. 24
      Hess, H. Engineering Applications of Biomolecular Motors. Annu. Rev. Biomed. Eng. 2011, 13, 429– 450,  DOI: 10.1146/annurev-bioeng-071910-124644
      24
      Engineering applications of biomolecular motors
      Hess, Henry
      Annual Review of Biomedical Engineering (2011), 13 (), 429-450CODEN: ARBEF7; ISSN:1523-9829. (Annual Reviews Inc.)
      A review. Biomol. motors, in particular motor proteins from the kinesin and myosin families, can be used to explore engineering applications of mol. motors in general. Their outstanding performance enables the exptl. study of hybrid systems, where bio-inspired functions such as sensing, actuation, and transport rely on the nanoscale generation of mech. force. Scaling laws and theor. studies demonstrate the optimality of biomol. motor designs and inform the development of synthetic mol. motors.
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    25. 25
      Kumar, S.; Månsson, A. Covalent and non-covalent chemical engineering of actin for biotechnological applications. Biotechnol. Adv. 2017, 35, 867– 888,  DOI: 10.1016/j.biotechadv.2017.08.002
      25
      Covalent and non-covalent chemical engineering of actin for biotechnological applications
      Kumar, Saroj; Mansson, Alf
      Biotechnology Advances (2017), 35 (7), 867-888CODEN: BIADDD; ISSN:0734-9750. (Elsevier)
      The cytoskeletal filaments are self-assembled protein polymers with 8-25 nm diams. and up to several tens of micrometres length. They have a range of pivotal roles in eukaryotic cells, including transportation of intracellular cargoes (primarily microtubules with dynein and kinesin motors) and cell motility (primarily actin and myosin) where muscle contraction is one example. For two decades, the cytoskeletal filaments and their assocd. motor systems have been explored for nanotechnol. applications including miniaturized sensor systems and lab-on-a-chip devices. Several developments have also revolved around possible exploitation of the filaments alone without their motor partners. Efforts to use the cytoskeletal filaments for applications often require chem. or genetic engineering of the filaments such as specific conjugation with fluorophores, antibodies, oligonucleotides or various macromol. complexes e.g. nanoparticles. Similar conjugation methods are also instrumental for a range of fundamental biophys. studies. Here we review methods for non-covalent and covalent chem. modifications of actin filaments with focus on crit. advantages and challenges of different methods as well as crit. steps in the conjugation procedures. We also review potential uses of the engineered actin filaments in nanotechnol. applications and in some key fundamental studies of actin and myosin function. Finally, we consider possible future lines of investigation that may be addressed by applying chem. conjugation of actin in new ways.
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    26. 26
      Kumar, S.; ten Siethoff, L.; Persson, M.; Lard, M.; te Kronnie, G.; Linke, H.; Månsson, A. Antibodies covalently immobilized on actin filaments for fast myosin driven analyte transport. PLoS One 2012, 7, e46298,  DOI: 10.1371/journal.pone.0046298
      26
      Antibodies covalently immobilized on actin filaments for fast myosin driven analyte transport
      Kumar, Saroj; ten Siethoff, Lasse; Persson, Malin; Lard, Mercy; te Kronnie, Geertruy; Linke, Heiner; Maansson, Alf
      PLoS One (2012), 7 (10), e46298CODEN: POLNCL; ISSN:1932-6203. (Public Library of Science)
      Biosensors would benefit from further miniaturization, increased detection rate and independence from external pumps and other bulky equipment. Whereas transportation systems built around mol. motors and cytoskeletal filaments hold significant promise in the latter regard, recent proof-of-principle devices based on the microtubule-kinesin motor system have not matched the speed of existing methods. An attractive soln. to overcome this limitation would be the use of myosin driven propulsion of actin filaments which offers motility one order of magnitude faster than the kinesin-microtubule system. Here, we realized a necessary requirement for the use of the actomyosin system in biosensing devices, namely covalent attachment of antibodies to actin filaments using heterobifunctional cross-linkers. We also demonstrated consistent and rapid myosin II driven transport where velocity and the fraction of motile actin filaments was negligibly affected by the presence of antibody-antigen complexes at rather high d. (>20 μm-1). The results, however, also demonstrated that it was challenging to consistently achieve high d. of functional antibodies along the actin filament, and optimization of the covalent coupling procedure to increase labeling d. should be a major focus for future work. Despite the remaining challenges, the reported advances are important steps towards considerably faster nanosepn. than shown for previous mol. motor based devices, and enhanced miniaturization because of high bending flexibility of actin filaments.
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    27. 27
      Kumar, S.; Milani, G.; Takatsuki, H.; Lana, T.; Persson, M.; Frasson, C.; te Kronnie, G.; Månsson, A. Sensing protein antigen and microvesicle analytes using high-capacity biopolymer nano-carriers. Analyst 2016, 141, 836– 846,  DOI: 10.1039/C5AN02377G
      27
      Sensing protein antigen and microvesicle analytes using high-capacity biopolymer nano-carriers
      Kumar, Saroj; Milani, Gloria; Takatsuki, Hideyo; Lana, Tobia; Persson, Malin; Frasson, Chiara; te Kronnie, Geertruy; Maansson, Alf
      Analyst (Cambridge, United Kingdom) (2016), 141 (3), 836-846CODEN: ANALAO; ISSN:0003-2654. (Royal Society of Chemistry)
      Lab-on-a-chip systems with mol. motor driven transport of analytes attached to cytoskeletal filament shuttles (actin filaments, microtubules) circumvent challenges with nanoscale liq. transport. However, the filaments have limited cargo-carrying capacity and limitations either in transportation speed (microtubules) or control over motility direction (actin). To overcome these constraints the authors here report incorporation of covalently attached antibodies into self-propelled actin bundles (nanocarriers) formed by crosslinking antibody conjugated actin filaments via fascin, a natural actin-bundling protein. The authors demonstrate high max. antigen binding activity and propulsion by surface adsorbed myosin motors. Analyte transport capacity is tested using both protein antigens and microvesicles, a novel class of diagnostic markers. Increased incubation concn. with protein antigen in the 0.1-100 nM range (1 min) reduces the fraction of motile bundles and their velocity but max. transportation capacity of >1 antigen per nm of bundle length is feasible. At sub-nanomolar protein analyte concn., motility is very well preserved opening for orders of magnitude improved limit of detection using motor driven concn. on nanoscale sensors. Microvesicle-complexing to monoclonal antibodies on the nanocarriers compromises motility but nanocarrier aggregation via microvesicles shows unique potential in label-free detection with the aggregates themselves as non-toxic reporter elements.
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    28. 28
      Korten, T.; Chaudhuri, S.; Tavkin, E.; Braun, M.; Diez, S. Kinesin-1 Expressed in Insect Cells Improves Microtubule in Vitro Gliding Performance, Long-Term Stability and Guiding Efficiency in Nanostructures. IEEE Trans. Nanobioscience 2016, 15, 62– 69,  DOI: 10.1109/TNB.2016.2520832
      28
      Kinesin-1 Expressed in Insect Cells Improves Microtubule in Vitro Gliding Performance, Long-Term Stability and Guiding Efficiency in Nanostructures
      Korten Till; Chaudhuri Samata; Tavkin Elena; Braun Marcus; Diez Stefan
      IEEE transactions on nanobioscience (2016), 15 (1), 62-9 ISSN:.
      The cytoskeletal motor protein kinesin-1 has been successfully used for many nanotechnological applications. Most commonly, these applications use a gliding assay geometry where substrate-attached motor proteins propel microtubules along the surface. So far, this assay has only been shown to run undisturbed for up to 8 h. Longer run times cause problems like microtubule shrinkage, microtubules getting stuck and slowing down. This is particularly problematic in nanofabricated structures where the total number of microtubules is limited and detachment at the structure walls causes additional microtubule loss. We found that many of the observed problems are caused by the bacterial expression system, which has so far been used for nanotechnological applications of kinesin-1. We strive to enable the use of this motor system for more challenging nanotechnological applications where long-term stability and/or reliable guiding in nanostructures is required. Therefore, we established the expression and purification of kinesin-1 in insect cells which results in improved purity and--more importantly--long-term stability > 24 h and guiding efficiencies of > 90% in lithographically defined nanostructures.
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    29. 29
      Korten, T.; Månsson, A.; Diez, S. Towards the Application of Cytoskeletal Motor Proteins in Molecular Detection and Diagnostic Devices. Curr. Opin. Biotechnol. 2010, 21, 477,  DOI: 10.1016/j.copbio.2010.05.001
      29
      Towards the application of cytoskeletal motor proteins in molecular detection and diagnostic devices
      Korten, Till; Mansson, Alf; Diez, Stefan
      Current Opinion in Biotechnology (2010), 21 (4), 477-488CODEN: CUOBE3; ISSN:0958-1669. (Elsevier B.V.)
      A review. Over the past ten years, great advancements have been made towards using biomol. motors for nanotechnol. applications. In particular, devices using cytoskeletal motor proteins for mol. transport are maturing. First efforts towards designing such devices used motor proteins attached to micro-structured substrates for the directed transport of microtubules and actin filaments. Soon thereafter, the specific capture, transport and detection of target analytes like viruses were demonstrated. Recently, spatial guiding of the gliding filaments was added to increase the sensitivity of detection and allow parallelization. Whereas mol. motor powered devices have not yet demonstrated performance beyond the level of existing detection techniques, the potential is great: Replacing microfluidics with transport powered by mol. motors allows integration of the energy source (ATP) into the assay soln. This opens up the opportunity to design highly integrated, miniaturized, autonomous detection devices. Such devices, in turn, may allow fast and cheap on-site diagnosis of diseases and detection of environmental pathogens and toxins.
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    30. 30
      Bachand, G. D.; Hess, H.; Ratna, B.; Satir, P.; Vogel, V. Smart dust” biosensors powered by biomolecular motors. Lab Chip 2009, 9, 1661– 1666,  DOI: 10.1039/b821055a
      30
      "Smart dust" biosensors powered by biomolecular motors
      Bachand, George D.; Hess, Henry; Ratna, Banahalli; Satir, Peter; Vogel, Viola
      Lab on a Chip (2009), 9 (12), 1661-1666CODEN: LCAHAM; ISSN:1473-0197. (Royal Society of Chemistry)
      The concept of a microfabricated biosensor for environmental and biomedical monitoring applications which is composed of environmentally benign components is presented. With a built-in power source (the biol. fuel ATP) and driven by biol. motors (kinesin), sensing in the microdevice can be remotely activated and the presence of a target mol. or toxin remotely detected. The multifaceted progress towards the realization of such a device is described.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXms12it7g%253D&md5=a790eedb012cfc5463fd1f321fd12d74
    31. 31
      Nicolau, D. V., Jr.; Lard, M.; Korten, T.; van Delft, F. C. M. J. M.; Persson, M.; Bengtsson, E.; Månsson, A.; Diez, S.; Linke, H.; Nicolau, D. V. Parallel computation with molecular-motor-propelled agents in nanofabricated networks. Proc. Natl. Acad. Sci. U. S. A. 2016, 113, 2591– 2596,  DOI: 10.1073/pnas.1510825113
      31
      Parallel computation with molecular-motor-propelled agents in nanofabricated networks
      Nicolau, Dan V., Jr.; Lard, Mercy; Korten, Till; van Delft, Falco C. M. J. M.; Persson, Malin; Bengtsson, Elina; Mansson, Alf; Diez, Stefan; Linke, Heiner; Nicolau, Dan V.
      Proceedings of the National Academy of Sciences of the United States of America (2016), 113 (10), 2591-2596CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
      The combinatorial nature of many important math. problems, including nondeterministic-polynomial-time (NP)-complete problems, places a severe limitation on the problem size that can be solved with conventional, sequentially operating electronic computers. There have been significant efforts in conceiving parallel-computation approaches in the past, for example: DNA computation, quantum computation, and microfluidics-based computation. However, these approaches have not proven, so far, to be scalable and practical from a fabrication and operational perspective. Here, we report the foundations of an alternative parallel-computation system in which a given combinatorial problem is encoded into a graphical, modular network that is embedded in a nanofabricated planar device. Exploring the network in a parallel fashion using a large no. of independent, mol.-motor-propelled agents then solves the math. problem. This approach uses orders of magnitude less energy than conventional computers, thus addressing issues related to power consumption and heat dissipation. We provide a proof-of-concept demonstration of such a device by solving, in a parallel fashion, the small instance {2, 5, 9} of the subset sum problem, which is a benchmark NP-complete problem. Finally, we discuss the tech. advances necessary to make our system scalable with presently available technol.
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    32. 32
      Bunk, R.; Klinth, J.; Montelius, L.; Nicholls, I. A.; Omling, P.; Tågerud, S.; Månsson, A. Actomyosin motility on nanostructured surfaces. Biochem. Biophys. Res. Commun. 2003, 301, 783– 788,  DOI: 10.1016/S0006-291X(03)00027-5
      32
      Actomyosin motility on nanostructured surfaces
      Bunk, Richard; Klinth, Jeanna; Montelius, Lars; Nicholls, Ian A.; Omling, Par; Tagerud, Sven; Mansson, Alf
      Biochemical and Biophysical Research Communications (2003), 301 (3), 783-788CODEN: BBRCA9; ISSN:0006-291X. (Elsevier Science)
      We have here, for the first time, used nanofabrication techniques to reproduce aspects of the ordered actomyosin arrangement in a muscle cell. The adsorption of functional heavy meromyosin (HMM) to five different resist polymers was first assessed. One group of resists (MRL-6000.1XP and ZEP-520) consistently exhibited high quality motility of actin filaments after incubation with HMM. A second group (PMMA-200, PMMA-950, and MRI-9030) generally gave low quality of motility with only few smoothly moving filaments. Based on these findings electron beam lithog. was applied to a bilayer resist system with PMMA-950 on top of MRL-6000.1XP. Grooves (100-200 nm wide) in the PMMA layer were created to expose the MRL-6000.1XP surface for adsorption of HMM and guidance of actin filament motility. This guidance was quite efficient allowing no U-turns of the filaments and approx. 20 times higher d. of moving filaments in the grooves than on the surrounding PMMA.
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    33. 33
      Månsson, A. Translational actomyosin research: fundamental insights and applications hand in hand. J. Muscle Res. Cell Motil. 2012, 33, 219,  DOI: 10.1007/s10974-012-9298-5
      33
      Translational actomyosin research: fundamental insights and applications hand in hand
      Mansson, Alf
      Journal of Muscle Research and Cell Motility (2012), 33 (3-4), 219-233CODEN: JMRMD3; ISSN:0142-4319. (Springer)
      This review describes the development towards actomyosin based nanodevices taking a starting point in pioneering studies in the 1990s based on conventional in vitro motility assays. Refs. are given to parallel developments using the kinesin-microtubule motor system. The early developments focused on achieving cargo-transportation using actin filaments as cargo-loaded shuttles propelled by surface-adsorbed heavy meromyosin along micro- and nanofabricated channels. These efforts prompted extensive studies of surface-motor interactions contributing with new insights of general relevance in surface and colloid chem. As a result of these early efforts, a range of complex devices have now emerged, spanning applications in medical diagnostics, biocomputation and formation of complex nanostructures by self-organization. In addn. to giving a comprehensive account of the developments towards real-world applications an important goal of the present review is to demonstrate important connections between the applied studies and fundamental biophys. studies of actomyosin and muscle function. Thus the manipulation of the motor proteins towards applications has resulted in new insights into methodol. aspects of the in vitro motiliy assay. Other developments have advanced the understanding of the dynamic materials properties of actin filaments.
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    34. 34
      Agarwal, A.; Hess, H. Biomolecular motors at the intersection of nanotechnology and polymer science. Prog. Polym. Sci. 2010, 35, 252,  DOI: 10.1016/j.progpolymsci.2009.10.007
      34
      Biomolecular motors at the intersection of nanotechnology and polymer science
      Agarwal, Ashutosh; Hess, Henry
      Progress in Polymer Science (2010), 35 (1-2), 252-277CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)
      A review. The dynamic cytoskeletal components, biomol. motors and their assocd. filaments, can be integrated in vitro with synthetic components to enable nanoscale transport systems. These "mol. shuttles" have generated significant scientific interest over the past decade, resulting in over 200 publications. This review focuses on the contributions involving the use of linear biomol. motors, kinesin and myosin, and their assocd. filaments, microtubule and actin, in device applications. Exploiting the naturally occurring motion between the motors and their assocd. filaments requires an interdisciplinary understanding of the underlying challenges. Three basic topics that most of the exptl. contributions have sought to address are: the guiding of shuttle movement, the loading and unloading of cargo onto the shuttles, and the control of motor activity. The phys. properties of motors and filaments det. the engineering solns. to the design challenges. The applications, which center on the basic capability of nanoscale motion, and the roadblocks to their widespread implementation will be discussed in detail.
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    35. 35
      Agarwal, A.; Hess, H. Molecular Motors as Components of Future Medical Devices and Engineered Materials. J. Nanotechnol. Eng. Med. 2009, 1, 11005– 11009,  DOI: 10.1115/1.3212823
      There is no corresponding record for this reference.
    36. 36
      Radi, A.-E.; Acero Sánchez, J. L.; Baldrich, E.; O’Sullivan, C. K. Reusable Impedimetric Aptasensor. Anal. Chem. 2005, 77, 6320– 6323,  DOI: 10.1021/ac0505775
      36
      Reusable Impedimetric Aptasensor
      Radi, Abd-Elgawad; Sanchez, Josep Lluis Acero; Baldrich, Eva; O'Sullivan, Ciara K.
      Analytical Chemistry (2005), 77 (19), 6320-6323CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      A novel impedimetric aptasensor using a mixed self-assembled monolayer composed of thiol-modified thrombin binding aptamer and 2-mercaptoethanol on a gold electrode is reported. The changes of interfacial features of the electrode were probed in the presence of the reversible redox couple, Fe(CN)63-/4-, using impedance measurements. The electrode surface was partially blocked due to the self-assembly of aptamer or the formation of the aptamer-thrombin complex, resulting in an increase of the interfacial electron-transfer resistance detected by electrochem. impedance spectroscopy or cyclic voltammetry. The aptasensor was regenerated by breaking the complex formed between the aptamer and thrombin using 2.0 M NaCl soln., and the immobilized aptamer subsequently was used for repeated detection of thrombin. The aptamer-functionalized electrode showed a linear response of the charge-transfer resistance to the increase of thrombin concn. in the range of 5.0-35.0 nM and the thrombin was easily detectable to a concn. of 2.0 nM.
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    37. 37
      Mattos, A. B.; Freitas, T. A.; Silva, V. L.; Dutra, R. F. A dual quartz crystal microbalance for human cardiac troponin T in real time detection. Sens. Actuators, B 2012, 161, 439– 446,  DOI: 10.1016/j.snb.2011.10.058
      37
      A dual quartz crystal microbalance for human cardiac troponin T in real time detection
      Mattos, A. B.; Freitas, T. A.; Silva, V. L.; Dutra, R. F.
      Sensors and Actuators, B: Chemical (2012), 161 (1), 439-446CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)
      An immunosensor based on dual quartz crystal microbalance (Dual-QCM) for human cardiac troponin T (cTnT) was developed. The self-assembled monolayer by cysteamine was used to immobilize the monoclonal antibody against cTnT (mAb-cTnT). The mAb-cTnT was immobilized on the amine-coated surface via glutaraldehyde. The effect of the cysteamine concns. on the SAM coated gold sensor was studied as a function of the amt. of the immobilized cTnT monoclonal antibodies. A good correlation was found between the cTnT concn. and frequency shift (r = 0.9983). The sensor surface was regenerated by using a soln. of 1% (w/v) sodium dodecyl sulfate without losing the immunoreactivity. In this work, it was possible to measure the cTnT without diln. of the human serum with good specificity and reproducibility. The limit of detection was 0.008 ng/mL in this Dual-QCM system. Application of the Dual-QCM immunosensor for clin. samples demonstrated that the results were in good agreement with Electrochemiluminescence Immunoassay (ECLIA).
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    38. 38
      Albrecht, C.; Kaeppel, N.; Gauglitz, G. Two immunoassay formats for fully automated CRP detection in human serum. Anal. Bioanal. Chem. 2008, 391, 1845,  DOI: 10.1007/s00216-008-2093-x
      38
      Two immunoassay formats for fully automated CRP detection in human serum
      Albrecht, Christiane; Kaeppel, Nina; Gauglitz, Guenter
      Analytical and Bioanalytical Chemistry (2008), 391 (5), 1845-1852CODEN: ABCNBP; ISSN:1618-2642. (Springer)
      Immunoassays are a proven approach towards fast, sensitive, cost-effective and easy-to-use anal. systems which are able to measure a variety of interesting analytes, esp. in medical diagnostics. Herein, the authors report two assay formats, binding inhibition and sandwich assay format, for detection of C-reactive protein (CRP) in human serum. Both assays were characterized and compared with respect to their suitability and adaptation into a complete sensor system. An automated, optical biosensor system, based on evanescent field technol., was used to carry out a full threefold calibration in each case. Owing to the resulting working ranges, 0.044-2.9 mg L-1 and 0.13-22.9 mg L-1, resp., the assays qualify for use in detecting high-sensitivity CRP (C-reactive protein).
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    39. 39
      Andersson, K.; Hämäläinen, M.; Malmqvist, M. Identification and Optimization of Regeneration Conditions for Affinity-Based Biosensor Assays. A Multivariate Cocktail Approach. Anal. Chem. 1999, 71, 2475– 2481,  DOI: 10.1021/ac981271j
      39
      Identification and Optimization of Regeneration Conditions for Affinity-Based Biosensor Assays. A Multivariate Cocktail Approach
      Andersson, Karl; Haemaelaeinen, Markku; Malmqvist, Magnus
      Analytical Chemistry (1999), 71 (13), 2475-2481CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      A general regeneration, identification, and optimization (RO) protocol for Biacore systems was developed. The RO protocol uses six multi-ingredient stock solns. that represent the six most common chem. properties employed as regeneration agents. The regeneration effect of different regeneration cocktails of these six stock solns. were tested iteratively until a satisfactory result was obtained. The RO protocol was designed with an ease-of-use and multivariate approach. The RO protocol was tested on 13 different antibody-antigen systems. For 10 of these, only the first screening session was tested. For 9 of the 13 systems, the RO-protocol screening session identified cocktails that removed more than 90% of the bound analyte in a 30 s pulse. For 5 systems, the RO protocol identified cocktails that regenerated the surface completely and that were more gentle than previously used regeneration conditions. Furthermore, the regeneration optimization results can be interpreted as a characterization of the interacting mols. The relevance of testing cocktails was justified by the fact that at least one cocktail was significantly better than all dild. stock solns. for all tested model systems. By using the multivariate approach, the risk of missing relevant combinations of stock solns. was minimized. This resulted in an unexpected discovery of excellent properties of EDTA as an additive in regeneration cocktails contg. chaotropic agents and ions in high concn.
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    40. 40
      Sankiewicz, A.; Tokarzewicz, A.; Gorodkiewicz, E. Regeneration of surface plasmone resonance chips for multiple use Regeneration of surface plasmone resonance chips for multiple use. Bulg. Chem. Commun. 2015, 47, 477– 482
      There is no corresponding record for this reference.
    41. 41
      Kumar Dixit, C. Surface Regeneration of Gold-Coated Chip for Highly-Reproducible Surface Plasmon Resonance Immunoassays. J. Biosens. Bioelectron. 2014, 05, 149,  DOI: 10.4172/2155-6210.1000149
      There is no corresponding record for this reference.
    42. 42
      Meguriya, K.; Kikuchi, S.; Kobayashi, N.; Yoshikawa, H. Y.; Nakabayashi, S.; Kawamura, R. Reversible surface functionalization of motor proteins for sustainable motility. Jpn. J. Appl. Phys. 2019, 58, SDDI01,  DOI: 10.7567/1347-4065/ab17ca
      There is no corresponding record for this reference.
    43. 43
      Månsson, A. Actomyosin based contraction: one mechanokinetic model from single molecules to muscle?. J. Muscle Res. Cell Motil. 2016, 37, 181– 194,  DOI: 10.1007/s10974-016-9458-0
      43
      Actomyosin based contraction: one mechanokinetic model from single molecules to muscle?
      Mansson Alf
      Journal of muscle research and cell motility (2016), 37 (6), 181-194 ISSN:.
      Bridging the gaps between experimental systems on different hierarchical scales is needed to overcome remaining challenges in the understanding of muscle contraction. Here, a mathematical model with well-characterized structural and biochemical actomyosin states is developed to that end. We hypothesize that this model accounts for generation of force and motion from single motor molecules to the large ensembles of muscle. In partial support of this idea, a wide range of contractile phenomena are reproduced without the need to invoke cooperative interactions or ad hoc states/transitions. However, remaining limitations exist, associated with ambiguities in available data for model definition e.g.: (1) the affinity of weakly bound cross-bridges, (2) the characteristics of the cross-bridge elasticity and (3) the exact mechanistic relationship between the force-generating transition and phosphate release in the actomyosin ATPase. Further, the simulated number of attached myosin heads in the in vitro motility assay differs several-fold from duty ratios, (fraction of strongly attached ATPase cycle times) derived in standard analysis. After addressing the mentioned issues the model should be useful in fundamental studies, for engineering of myosin motors as well as for studies of muscle disease and drug development.
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    44. 44
      Uyeda, T. Q. P.; Kron, S. J.; Spudich, J. A. Myosin step size: Estimation from slow sliding movement of actin over low densities of heavy meromyosin. J. Mol. Biol. 1990, 214, 699– 710,  DOI: 10.1016/0022-2836(90)90287-V
      44
      Myosin step size. Estimation from slow sliding movement of actin over low densities of heavy meromyosin
      Uyeda, Taro Q. P.; Kron, Stephen J.; Spudich, James A.
      Journal of Molecular Biology (1990), 214 (3), 699-710CODEN: JMOBAK; ISSN:0022-2836.
      The step size of the myosin cross-bridge (d, displacement of an actin filament per one ATP hydrolysis) was estd. in an in vitro motility assay system by measuring the velocity of slowly moving actin filaments over low densities of heavy meromyosin on a nitrocellulose surface. In previous studies, only filaments greater than a min. length were obsd. to undergo continuous sliding movement. These filaments moved at the max. speed (v0), while shorter filaments dissocd. from the surface. The authors have now modified the assay system by including 0.8% methylcellulose in the ATP soln. Under these conditions, filaments shorter than the previous min. length move, but significantly slower than v0, as they are propelled by a limited no. of myosin heads. These data are consistent with a model that predicts that the sliding velocity (v) of slowly moving filaments is detd. by the product of v0 and the fraction of time when at least one myosin head is propelling the filament, i.e., v = v0 {1 - (1 - ts/tc)N}, where ts is the time the head is strongly bound to actin, tc is the cycle time of ATP hydrolysis, and N is the av. no. of myosin heads that can interact with the filament. Using this equation, the optimum value of ts/tc to fit the measured relationship between v and N was calcd. to be 0.050. Assuming d = v0ts, the step size was then calcd. to be 10-28 nm per ATP hydrolyzed, the latter value representing the upper limit. This range is within that of geometric constraint for conformational change imposed by the size of the myosin head, and therefore is not inconsistent with the swinging cross-bridge model tightly coupled with ATP hydrolysis.
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    45. 45
      Sundberg, M.; Balaz, B.; Bunk, R.; Rosengren-Holmberg, J. P.; Montelius, L.; Nicholls, I. A.; Omling, P.; Tågerud, S.; Månsson, A. Selective spatial localization of actomyosin motor function by chemical surface patterning. Langmuir 2006, 22, 7302,  DOI: 10.1021/la060365i
      45
      Selective Spatial Localization of Actomyosin Motor Function by Chemical Surface Patterning
      Sundberg, Mark; Balaz, Martina; Bunk, Richard; Rosengren-Holmberg, Jenny P.; Montelius, Lars; Nicholls, Ian A.; Omling, Paer; Tgerud, Sven; Mnsson, Alf
      Langmuir (2006), 22 (17), 7302-7312CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
      We have previously described the efficient guidance and unidirectional sliding of actin filaments along nanosized tracks with adsorbed heavy meromyosin (HMM; myosin II motor fragment). In those expts., the tracks were functionalized with trimethylchlorosilane (TMCS) by chem. vapor deposition (CVD) and surrounded by hydrophilic areas. Here we first show, using in vitro motility assays on nonpatterned and micropatterned surfaces, that the quality of HMM function on CVD-TMCS is equiv. to that on std. nitrocellulose substrates. We further examine the influences of phys. properties of different surfaces (glass, SiO2, and TMCS) and chem. properties of the buffer soln. on motility. With the presence of methylcellulose in the assay soln., there was HMM-induced actin filament sliding on both glass/SiO2 and on TMCS, but the velocity was higher on TMCS. This difference in velocity increased with decreasing contact angles of the glass and SiO2 surfaces in the range of 20-67° (advancing contact angles for water droplets). The corresponding contact angle of CVD-TMCS was 81°. In the absence of methylcellulose, there was high-quality motility on TMCS but no motility on glass/SiO2. This observation was independent of the contact angle of the glass/SiO2 surfaces and of HMM incubation concns. (30-150 μg mL-1) and ionic strengths of the assay soln. (20-50 mM). Complete motility selectivity between TMCS and SiO2 was obsd. for both nonpatterned and for micro- and nanopatterned surfaces. Spectrophotometric anal. of HMM depletion during incubation, K/EDTA ATPase measurements, and total internal reflection fluorescence spectroscopy of HMM binding showed only minor differences in HMM surface densities between TMCS and SiO2/glass. Thus, the motility contrast between the two surface chemistries seems to be attributable to different modes of HMM binding with the hindrance of actin binding on SiO2/glass.
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    46. 46
      Schneider, C. A.; Rasband, W. S.; Eliceiri, K. W. NIH Image to ImageJ: 25 years of image analysis. Nat. Methods 2012, 9, 671,  DOI: 10.1038/nmeth.2089
      46
      NIH Image to ImageJ: 25 years of image analysis
      Schneider, Caroline A.; Rasband, Wayne S.; Eliceiri, Kevin W.
      Nature Methods (2012), 9 (7_part1), 671-675CODEN: NMAEA3; ISSN:1548-7091. (Nature Publishing Group)
      For the past 25 years NIH Image and ImageJ software have been pioneers as open tools for the anal. of scientific images. We discuss the origins, challenges and solns. of these two programs, and how their history can serve to advise and inform other software projects.
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    47. 47
      Ionov, L.; Stamm, M.; Diez, S. Size Sorting of Protein Assemblies Using Polymeric Gradient Surfaces. Nano Lett. 2005, 5, 1910– 1914,  DOI: 10.1021/nl051235h
      47
      Size Sorting of Protein Assemblies Using Polymeric Gradient Surfaces
      Ionov, Leonid; Stamm, Manfred; Diez, Stefan
      Nano Letters (2005), 5 (10), 1910-1914CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      We report on a novel approach for the size-dependent fractionation of protein assemblies on polymeric surfaces. Using a simple temp. gradient method to generate one-dimensional gradients of grafted poly(ethylene glycol), we fabricated silicon-oxide chips with a gradually changing surface d. of kinesin motor mols. We demonstrate that such a bioactive surface can be used to sort gliding microtubules according to their length. To our knowledge, this is the first example of the self-organized sorting of protein assemblies on surfaces.
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    48. 48
      Ruhnow, F.; Kloβ, L.; Diez, S. Challenges in Estimating the Motility Parameters of Single Processive Motor Proteins. Biophys. J. 2017, 113, 2433– 2443,  DOI: 10.1016/j.bpj.2017.09.024
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      Challenges in Estimating the Motility Parameters of Single Processive Motor Proteins
      Ruhnow, Felix; Kloβ, Linda; Diez, Stefan
      Biophysical Journal (2017), 113 (11), 2433-2443CODEN: BIOJAU; ISSN:0006-3495. (Cell Press)
      Cytoskeletal motor proteins are essential to the function of a wide range of intracellular mechano-systems. The biophys. characterization of their movement along their filamentous tracks is therefore of large importance. Toward this end, single-mol., in vitro stepping-motility assays are commonly used to det. motor velocity and run length. However, comparing results from such expts. proved difficult due to influences from variations in the exptl. conditions and the data anal. methods. Here, the authors study the movement of fluorescently labeled, processive, dimeric motor proteins and propose a unified algorithm to correct the measurements for finite filament length as well as photobleaching. Particular emphasis is put on estg. the statistical errors assocd. with the proposed evaluation method, as knowledge of these values is crucial when comparing measurements from different expts. Testing the authors' approach with simulated and exptl. data from GFP-labeled kinesin-1 motors stepping along immobilized microtubules, the authors show (1) that velocity distributions should be fitted by a t location-scale probability d. function rather than by a normal distribution; (2) that the impossibility to measure events shorter than the image acquisition time needs to be taken into account; (3) that the interaction time and run length of the motors can be estd. independent of the filament length distribution; and (4) that the dimeric nature of the motors needs to be considered when correcting for photobleaching. Moreover, the authors' anal. reveals that controlling the temp. during the expts. with a precision <1 K is of importance. The authors believe the authors' method will not only improve the evaluation of exptl. data, but also allow for better statistical comparisons between different populations of motor proteins (e.g., with distinct mutations or linked to different cargos) and filaments (e.g., in distinct nucleotide states or with different posttranslational modifications). Therefore, the authors include a detailed workflow for image processing and anal. (including MATLAB code), serving as a tutorial for the estn. of motility parameters in stepping-motility assays.
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    49. 49
      van den Heuvel, M. G. L.; Butcher, C. T.; Smeets, R. M. M.; Diez, S.; Dekker, C. High Rectifying Efficiencies of Microtubule Motility on Kinesin-Coated Gold Nanostructures. Nano Lett. 2005, 5, 1117– 1122,  DOI: 10.1021/nl0506554
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      High Rectifying Efficiencies of Microtubule Motility on Kinesin-Coated Gold Nanostructures
      van den Heuvel, Martin G. L.; Butcher, Christopher T.; Smeets, Ralph M. M.; Diez, Stefan; Dekker, Cees
      Nano Letters (2005), 5 (6), 1117-1122CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      The authors demonstrate highly efficient rectification of microtubule motility on gold nanofabricated structures. First, the authors present a novel nanofabrication process for the creation of gold tracks for microtubule motility recessed in silicon oxide. This approach is particularly useful because it enables the use of the well-understood PEG-silane chem. on SiO2 for the blocking of kinesin, whereas the gold tracks allow possible elec. control. The authors demonstrate excellent confinement of microtubule motility to the gold nanostructures and that microtubules move on the gold with speeds comparable to that on glass. Second, the authors present designs of three advanced rectifier geometries. The authors analyze the microtubule pathways through the geometries, and the authors demonstrate highly efficient rectification with up to 92% efficiency. As a result, the authors find that up to 97% of the microtubules move unidirectionally.
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    50. 50
      Thoms, S.; Macintyre, D. S. Investigation of CSAR 62, a new resist for electron beam lithography. J. Vac. Sci. Technol., B: Nanotechnol. Microelectron.: Mater., Process., Meas., Phenom. 2014, 32, 06FJ01  DOI: 10.1116/1.4899239
      There is no corresponding record for this reference.
    51. 51
      Lindberg, F. W.; Norrby, M.; Rahman, M. A.; Salhotra, A.; Takatsuki, H.; Jeppesen, S.; Linke, H.; Månsson, A. Controlled Surface Silanization for actin–myosin Based Nanodevices and Biocompatibility of New Polymer Resists. Langmuir 2018, 34, 8777– 8784,  DOI: 10.1021/acs.langmuir.8b01415
      51
      Controlled Surface Silanization for Actin-Myosin Based Nanodevices and Biocompatibility of New Polymer Resists
      Lindberg, Frida W.; Norrby, Marlene; Rahman, Mohammad A.; Salhotra, Aseem; Takatsuki, Hideyo; Jeppesen, Soeren; Linke, Heiner; Maansson, Alf
      Langmuir (2018), 34 (30), 8777-8784CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
      Mol. motor-based nanodevices require organized cytoskeletal filament guiding along motility-promoting tracks, confined by motility-inhibiting walls. One way to enhance motility quality on the tracks, particularly in terms of filament velocity but also the fraction of motile filaments, is to optimize the surface hydrophobicity. The authors have studied the potential to achieve this for the actin-myosin II motor system on trimethylchlorosilane (TMCS)-derivatized SiO2 surfaces to be used as channel floors in nanodevices. The authors have also studied the ability to suppress motility on two new polymer resists, TU7 (for nanoimprint lithog.) and CSAR 62 (for electron beam and deep UV lithog.), to be used as channel walls. The authors developed a CVD tool for silanizing SiO2 surfaces in a controlled environment to achieve different surface hydrophobicities (measured by water contact angle). In contrast to previous work, the authors were able to fabricate a wide range of contact angles by varying the silanization time and chamber pressure using only one type of silane. This resulted in a significant improvement of the silanization procedure, producing a predictable contact angle on the surface and thereby predictable quality of the heavy meromyosin (HMM)-driven actin motility with regard to velocity. The authors obsd. a high degree of correlation between the filament sliding velocity and contact angle in the range 10-86°, expanding the previously studied range. The sliding velocity on TU7 surfaces was superior to that on CSAR 62 surfaces despite similar contact angles. In addn., the authors were able to suppress the motility on both TU7 and CSAR 62 by plasma oxygen treatment before silanization. These results are discussed in relation to previously proposed surface adsorption mechanisms of HMM and their relation to the water contact angle. Addnl., the results are considered for the development of actin-myosin based nanodevices with superior performance with respect to actin-myosin functionality.
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  • Supporting Information

    Supporting Information

    The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.nanolett.9b02738.

    • Methodological details for all parts of the manuscript, supplementary results considering Figures S1–S5 in greater detail. Supplementary figures and tables contain information as follows: Regeneration of trimethylchlorosilane derivatized glass surfaces only with SDS (Figure S1), efficiency of regenerating trimethylchlorosilane derivatized glass surfaces with only Proteinase K. (Figure S2), efficiency of SDS (0–5%) inclusion after Proteinase K (1h) treatment for regenerating trimethylchlorosilane derivatized glass surfaces (Figure S3), efficiency of the optimized regeneration protocol on flat as well as on micro/nanostructured surfaces with Triton X100 as detergent (Figure S4), regeneration of TMCS-derivatized and ARP (CSAR62) micropatterned surface for actomyosin motility (Figure S5), summary of findings with different approaches to test recycling of trimethylchlorosilane derivatized glass surfaces (Table S1), and fraction of stuck microtubules in a motility assay before (control) and after surface regeneration (Table S2) (PDF)

    • In vitro motility assay, using actin–myosin system, on HMM-coated TMCS-derivatized SiO2 surface before surface regeneration (AVI)

    • In vitro motility assay, using actin–myosin system, on HMM-coated TMCS-derivatized SiO2 surface after surface regeneration (AVI)

    • In vitro motility assay, using microtubule–kinesin system, on a glass-surface before surface regeneration (AVI)

    • In vitro motility assay, using microtubule–kinesin system, on glass-surface after surface regeneration (AVI)

    • In vitro motility assay, using microtubule–kinesin system, within channels (width = 1 μm) on a structured SiO2-surface before surface regeneration (AVI)

    • Representative in vitro motility assay, using microtubule–kinesin system, within channels (width = 1 μm) on a structured SiO2-surface after surface regeneration (AVI)

    • In vitro motility assay, using actin–myosin system, on HMM-coated TMCS-derivatized nanostructured surface before surface regeneration (AVI)

    • In vitro motility assay, using actin–myosin system, on HMM-coated TMCS-derivatized nanostructured surface after surface regeneration (AVI)


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