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Investigation of the Antibacterial Effect of Mesoporous Magnesium CarbonateClick to copy article linkArticle link copied!
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Division of Nanotechnology and Functional Materials, Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Box 534, 751 21 Uppsala, Sweden
*E-mail: [email protected] (K.W.).
*E-mail: [email protected] (M.S.).
Abstract
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Mesoporous magnesium carbonate (MMC) was first presented in 2013, and this material is currently under consideration for use in a number of biotechnological applications including topical formulations. This study presents the first evaluation of the antibacterial properties of the material with mesoporous silica and two other magnesium-containing powder materials used as references. All powder materials in this study are sieved to achieve a particle size distribution between 25 and 75 μm. The Gram-positive bacterium Staphylococcus epidermidis is used as the model bacterium due to its prevalence on human skin, its likelihood of developing resistance to antibiotics, for example, from routine exposure to antibiotics secreted in sweat, and because it is found inside affected acne vulgaris pores. Quantification of bacterial viability using a metabolic activity assay with resazurin as the fluorescent indicator shows that MMC exerts a strong antibacterial effect on the bacteria and that alkalinity accounts for the major part of this effect. The results open up for further development of MMC in on-skin applications where bacterial growth inhibition without using antibiotics is deemed favorable.
Copyright © 2016 American Chemical Society
Introduction
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About twice in a century, basic advances in science and technology bring about a total change in society, industry, and our everyday life. We are now beginning to approach the phase in which only incremental developments are to be expected from our latest major advance, the development of computers that has created a revolution in information and communication technology. Right now many indicators point toward the fact that advanced materials technology or nanotechnology will be the driver of the next science and technology revolution, (1-3) and the reason is that such technology has given us tools to decide which properties we want to give our materials. We are no longer at the mercy of the properties nature has given our materials but can instead start to precisely tailor them.
To exemplify, we have started to develop nanomaterial-based solar cells with the potential of outperforming those currently on the market by several hundred percent in efficiency, depending on significantly smaller amounts of material than in current solar cells, (4) nanostructured batteries based on sustainable materials such as cellulose and conducting polymers (5, 6) or organic radical polymers, (7) targeted nanotechnology-based cancer treatments based on passive and active targeting of tumor cells, (8) and a number of other medicine inventions. (9) In spite of the great opportunity of nanotechnology within both energy technology and medicine, the cosmetics industry was among the first to implement nanotechnological principles in product development. (10) When it comes to skin care products based on nanotechnological principles, the borderline between cosmetics and medicine is thin. New nanostructures allow for delivery of both active pharmaceutical ingredients as well as purely cosmetic agents to different layers of the skin (topical) as well as through the skin (transdermal) to cause systemic effects.
Mesoporous nanomaterials constitute a very promising class of materials in such areas of use due to their tunable pore structure that can be adjusted to the ingredients to be loaded into, and subsequently released from, them. For example, such materials are presently evaluated for haircare, (10) dermal delivery of pharmaceutical compounds such as small interfering RNA to treat fibrosis, (11) and as delivery vehicles for peptides (12) and vitamins in cosmetic formulations. (13) The most frequently studied type of mesoporous material for such applications is mesoporous silica, whose synthesis typically relies on the use of organic template molecules (14, 15) and relatively high calcination temperatures to create the desired pore structure.
In 2013, we presented the template-free synthesis of a mesoporous magnesium carbonate (MMC) material, commercialized as Upsalite, (16) that is synthesized in a low-temperature process and has a well-defined pore size distribution. (17) In addition to its ability to absorb a large amount of moisture, (16, 18, 19) this material has recently been found to be able to stabilize poorly soluble drugs incorporated into the mesopore structure of the material, thus enhancing their dissolution rate. (20, 21) The material, which consists of amorphous magnesium carbonate and a small portion of crystalline magnesium oxide, has further been indicated to be safe to use on skin as it, even at very high concentrations, was shown to be nontoxic for human dermal fibroblast cells and to not induce cutaneous reactions in in vivo skin irritation tests. In addition, no evidence of systemic toxicity was found when saline extracts of the material were injected in mice. (22)
The above findings spur us to further investigate biomedical, and in particular on-skin, application areas of use for MMC. In this work, we present the first analysis of the antibacterial properties of this material and compare them with those of mesoporous silica and two other magnesium-containing powder materials to elucidate the mechanism of the observed properties. The Gram-positive bacterium Staphylococcus epidermidis is used as a model in this study due to its prevalence on human skin and also due to its likelihood of developing resistance to antibiotics, for example, from routine exposure to antibiotics secreted in sweat. (23) In addition, the bacterium is found inside affected acne vulgaris pores. (24)
Results
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Characterization of Sample Particles
Figure 1 displays scanning electron microscopy (SEM) images of a sieved particle from each of the four materials included in this study. Particles of MMC were generally single pieces of material corresponding in size to the sieved interval 25–75 μm, whereas particles of the three other materials consist of aggregates of much smaller primary particles.
Figure 1
Figure 1. SEM images of a sieved sample particle of (a) MMC, (b) MgO, (c) SBA-15, and (d) magnesium carbonate basic.
Antibacterial Test
The antibacterial effect of MMC in comparison to magnesium oxide, mesoporous silica, and magnesium carbonate basic was assessed with the help of the metabolic activity assay (MAA) containing the metabolic indicator resazurin. The fluorescence of the assay containing the samples and bacteria provides a measure of the viability of the bacteria when corrected for the background fluorescence of the samples without bacteria. Figure 2 displays the fluorescence signals and thus the viability of the bacteria in contact with the four powder samples, as well as the viability of the negative control containing phosphate-buffered saline (PBS) without any powder. The PBS measurement was taken from the well with the highest bacterial concentration in the standard curve, which was identical to the bacteria concentration used with all powder samples. Measurements of the standard curve (not displayed) showed good linearity between fluorescence levels and bacteria concentrations at all measurement times.
Figure 2
Figure 2. Viability measurements as a function of time for bacteria in contact with MMC, magnesium oxide, mesoporous silica, and magnesium carbonate basic in comparison to the negative control PBS. Solid lines are guides to the eye, whereas the dashed line represents an exponential fit to the data for PBS. Data represent mean ± 1 sd for n = 3.
The viability measurements of bacteria in PBS indicate a relatively uninhibited growth, as can be seen by the exponential increase in fluorescence measurements. An exponential fit to the data provides a generation or doubling time of the bacteria of ln(2)/0.897 h ≈ 46 min. Both MMC and MgO indicate a strong antibacterial effect against S. epidermidis. Magnesium carbonate basic also shows a strong effect, albeit not to the same degree as MMC and MgO. Mesoporous silica does not show any effect for the first hour compared to PBS, but subsequent measurements show an effect that reduced the bacterial growth/viability compared to PBS. After 3 h, the viability reductions compared to PBS were 71, 96, 100, and 100% for SBA-15, magnesium carbonate basic, MgO, and MMC, respectively.
Recovery Test
Results from the antibacterial test shown above indicate a strong antibacterial effect and/or growth inhibition for three of the materials tested. To determine whether the bacteria were completely inactivated, a recovery test was carried out where the bacteria were first separated from the powder suspension and MAA solution, and then reintroduced into a fresh MAA without sample particles. Figure 3 shows the growth curves of the bacteria that were previously subjected to the antibacterial test. All samples show some degree of viability, indicating that the bacteria were not completely killed during the antibacterial test, despite the fact that the viability reduction was nearly complete for MgO and MMC (see Figure 2). Generally, the rate of growth, indicated by the increasing levels of fluorescence in Figure 3, appears to correspond to the degree of viability reduction observed in the antibacterial test. The fluorescence levels are the lowest for MgO, suggesting that the antibacterial effect of MgO was the strongest. Although the viability of the bacteria in contact with MMC was at least as low as that for MgO in the previous test, the bacteria appear to have recovered to a greater extent when removed from contact with MMC. This suggests that although MMC completely inhibited the growth of S. epidermidis, it did not completely kill the bacteria.
Figure 3
Figure 3. Fluorescence measurements showing the growth of bacteria suspensions after separation from the powder samples at the end of the antibacterial test. The legend indicates which sample powder the bacteria had previously been in contact with. Lines represent exponential fits to the data, with corresponding equations provided in the top left corner of the plot.
Exponential curves are fitted to the data in Figure 3, and the corresponding equations can also be found in the plot. It is interesting to note that the generation time of the bacteria previously in contact with the SBA-15 powder was shorter than the generation time of bacteria that had not been in contact with any powder in the previous antibacterial test (28 min versus 46 min; see the PBS sample in Figure 2). This could likely be explained by the higher concentration of the Mueller–Hinton (MH) broth that was used in the MAA for the recovery test that consequently led to a higher growth rate.
Effect of Media pH
To investigate the effect of pH on the viability of S. epidermidis, the pH of the MAA media was adjusted between 7.4 and 10.5 by the addition of NaOH, and the fluorescence was measured after 30 min. Figure 4 displays the results of the test where the relative viabilities of the bacterial suspensions are shown relative to the unadjusted MAA media at pH = 7.4. It can be seen that a more alkaline environment reduces the viability of S. epidermidis or at least suppresses the growth; 90% viability/growth reduction is achieved with a pH of 9.11, whereas complete inhibition is observed at pH = 10.54.
Figure 4
Figure 4. Relative viability of bacterial suspensions at pH ranging from 7.4 to 10.54, referenced to the viability of the unadjusted media at pH = 7.4. Data represent mean ± 1 sd for n = 3.
Controlling for Effects of Media pH and Particles
An additional antibacterial test was performed with MMC, SBA-15, and MgO with the aim to separate antibacterial effects due to contact with the particles themselves from the effects due to possible substances leached from the materials. The test was performed in a MAA with sufficient buffer capacity to maintain the pH despite the presence of the basic materials being tested. This buffer capacity was verified by measuring the pH of the MAA solution containing the different sample powders over 4 h, which proved to be 7.25 ± 0.02, 7.10 ± 0.02, and 7.34 ± 0.02 for MMC, SBA-15, and MgO, respectively. This contrasts with the pH of the MAA solution containing the powders in the first antibacterial test, where the pH was found to be 8.39, 7.32, and 9.76 for MMC, SBA-15, and MgO, respectively.
Figure 5 displays the fluorescence signals, corresponding to the viability, of the bacteria in contact with the three powder samples, as well as that of the negative control containing PBS without any powder. As in the first antibacterial test detailed above, the PBS measurement corresponded to the well with the highest bacterial concentration in the standard curve, which was identical to the bacteria concentration used with all powder samples. Measurements of the standard curve (not displayed) showed good linearity between fluorescence levels and bacteria concentrations at all measurement times. Fluorescence signals were concurrently recorded on the bacteria suspensions placed in the filtered solutions in which the powder samples had previously been soaked. Differences between these fluorescence levels and the corresponding fluorescence levels from particle-containing wells were not statistically significant (unpaired Student t-test, p > 0.05), and thus, only the fluorescence measurements from the bacterial suspensions in contact with the sample particles are displayed.
Figure 5
Figure 5. Viability measurements as a function of time for bacteria in contact with MMC, magnesium oxide, and mesoporous silica in concentrated PBS (phosphate concentration 0.3 M). A negative control without powder (denoted PBS) is provided for comparison. Solid lines are provided as guides to the eye. Data represent mean ± 1 sd for n = 3.
The growth behavior of bacteria in only PBS is markedly different from that shown in Figure 2 for only PBS. In Figure 5, the growth rate of bacteria in PBS decreases as the test proceeds instead of following the exponential profile observed in Figure 2. This can be attributed to the high ion concentration of concentrated PBS, making the medium hypertonic relative to the bacterial cells and leading to loss of water from the bacterial cells due to osmosis. On examining the fluorescence of the bacteria suspensions in contact with particles, there appears to be an initial viability reduction relative to the PBS sample after 15 min (61, 63, and 40% for MMC, MgO, and SBA-15, respectively), but after continued contact with the particles, the viability increases relative to the viability of bacteria in PBS. After approximately 2 h, the viability of the bacteria subjected to SBA-15 match and follow that of bacteria in PBS, whereas the viability of both MMC and MgO continues to grow linearly and exceeds the viability of bacteria in PBS by as much as 47% (for the bacteria in contact with MMC particles after 4 h).
Discussion
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In this study, MMC was investigated for antibacterial activity against S. epidermidis. Information about the bactericidal properties of this material is important for the development of applications, such as topical formulations. Equally important is obtaining information on the biocompatibility of this mesoporous material. Recently, MMC was subjected to a toxicological evaluation through in vitro cytotoxicity, skin irritation, and acute systemic toxicity in vivo tests. (22) These tests showed that the material was nontoxic for human dermal fibroblasts cells up to a concentration of 1 mg/mL after 48 h exposure and that topical application of MMC resulted in negligible cutaneous reactions.
It is clear from the antibacterial test (cf. Figure 2) that MMC exhibits strong antibacterial activity against S. epidermidis at a concentration of 1 mg/mL, resulting in essentially no bacterial viability during the entire three-hour test. Three possible mechanisms have been proposed for the antibacterial activity of materials similar to those used in this study, namely, direct interaction of particles with bacteria, (25-27) an alkaline effect, (28, 29) and the formation of reactive oxygen species (ROS). (30-37)
Figure 4 proves that S. epidermidis bacteria are sensitive to an alkaline environment and therefore it is reasonable to expect some degree of alkaline effect from MMC because the addition of 1 mg/mL powder raised the pH of the MAA media to 8.39. The increase in pH with MMC is likely due to the residual MgO present in the material as previously shown. (17) However, from Figure 4 we would only expect approximately 65% reduction in viability with a media pH of 8.39, whereas Figure 2 shows a 100% viability reduction (although the bacteria are not permanently inactivated, as indicated by the recovery test shown in Figure 3). Therefore, the alkalinity of the MAA solution cannot entirely explain the antibacterial activity of MMC. With the MgO sample, which also resulted in a 100% viability reduction, the alkalinity of the MAA media (pH = 9.76) can explain a larger proportion of the antibacterial effect but still not all of it because Figure 4 indicates that a pH greater than 10 is required for complete viability reduction of S. epidermidis. A possible explanation for this increased antibacterial activity could be the increased pH of a thin layer of water surrounding the particles that results in damage to the bacterial cell membrane when coming in contact with the particles. (28) The bacteria are more likely to come into contact with the particles if they are electrostatically attracted to each other. S. epidermidis, like most bacteria, carry a net negative surface charge under typical physiological conditions (38) and thus would be attracted to positively charged substrates in the media. The isoelectric point (IEP) for MgO is around 12, (39) which means that it carries a positive charge in media with a pH less than 12 and would attract the negatively charged S. epidermidis. Previously, the surface charge of MgO nanoparticles has been determined to be positive, and thus attractive, to both Gram-positive and Gram-negative bacteria. (27) A similar situation may exist for MMC because it contains some residual MgO, although the IEP for the crystalline form of magnesium carbonate, magnesite, is only 6.8. (40) In the case of SBA-15 particles, another mechanism must be responsible for the viability reduction because this material did not alter the pH of the MAA media, and its IEP is around 3.6, (41) meaning it would be negatively charged in the media.
Interaction between bacteria and particles in direct contact with them is another mechanism of antibacterial activity. As discussed above, particles can be electrostatically attracted to bacteria due to their surface charge and the subsequent absorption can damage the cell membrane, (25-27) and perhaps the particles can even enter the interior of the cells. (25) Typically, this occurs with nanoparticles where smaller particles show increased antibacterial activity. (25, 26) In the current study, all samples were sieved to a 25–75 μm particle (or aggregate) size distribution, and therefore, such direct interaction between the particles and bacteria was not expected to be as great as it would be if the particles or aggregates were nanosized. However, for samples other than MMC, particles consist of aggregates of much smaller primary particles, where at least one dimension is on the order of 1 μm or less, as can be observed in Figure 1. It is highly likely that the mechanical agitation during testing caused some of these particles to break into smaller ones, which may have led to an increased antibacterial effect for these materials. The diameter of the S. epidermidis bacteria used in this study is just under 1 μm (42) and therefore it is possible that the smaller primary particles of some sample materials may interact strongly with the bacteria, or perhaps even enter into the bacteria, and cause an antibacterial effect. This would not be the case for MMC in which the particles are clearly not composed of smaller primary nanoparticles.
The third possible mechanism to the antibacterial activity is the generation of ROS, such as the superoxide ion (O2–). For example, several studies have shown that MgO particles generate superoxide ions (30-33) and that a larger surface area increases the effect. This may be applicable in the case of MMC particles, which have a surface area of 207 m2/g. It has also been shown that SBA-15 particles at a concentration of 1 mg/mL generate superoxide ions that cause cytotoxic effects on Caco-2 cells. (43) The specific surface area of SBA-15 was previously measured to be 428 m2/g. (22) Thus, it is likely that generation of ROS is responsible for the antibacterial effect of SBA-15 observed in this study. Similarly, the high surface area of MMC particles, which also contain some residual MgO, suggests that ROS provide a significant contribution to the observed antibacterial effect.
Finally, we return to the results where attempts to control the effects of media pH and particles were made. As described above, a major contributor to the antibacterial activity is deemed to be the increased alkalinity of the MAA media, at least in the case of MMC and MgO particles. By increasing the buffer capacity of the MAA solution, the pH for all samples was the same as the PBS reference, and thus, the effect of alkalinity was removed. Figure 5 showed that no sample material had a viability that was reduced compared to the PBS reference (in fact MMC and MgO had increased viability levels after 3 h compared to the PBS reference). However, as discussed above, alkalinity effects of the MAA media should not have accounted for the entire antibacterial effect. As such, some effect of the particles was also expected, but this was not observed because there was no statistical difference between the results with or without particles. A likely explanation for this lack of effect seen with particles compared to without particles is the electrostatic screening caused by the very high ion concentration of the phosphate buffer (0.3 M). This screening would likely decrease the attraction and thus interaction between particles and bacteria, and consequently reduce effects due to direct contact, ROS generation, or local pH increase close to the particle surface.
In summary, alkalinity accounts for the major part of MMC’s antibacterial activity toward S. epidermidis, although it cannot entirely explain the effect. Other contributions to this antibacterial effect are likely due to the generation of ROS such as O2–, direct contact with the particles, and/or an increased pH in close proximity to the particles. Future studies should be directed at elucidating the mechanisms behind the antibacterial activity, as well as determining this activity against other bacterial strains and microorganisms. For example, it is known that oxides like MgO and ZnO are more effective against Gram-positive than Gram-negative bacteria (36) and that the susceptibility to alkalinity and ROS varies with bacteria strain.
Methods
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Sample Preparation and Characterization
Synthesis of MMC (Upsalite) was carried out as described previously, (22) with the exception that the material was ground in a mortar to reduce the particle size and thereafter sieved to obtain a powder with a particle size distribution between 25 and 75 μm. The material had a surface area of 207 m2/g, a pore volume of 0.34 cm3/g, an average pore size of 5.3 nm, and a density of 2.28 g/cm3. Details of the characterization can be found elsewhere. (22)
Three other materials were included in the study: mesoporous silica (SBA-15; ACS Material, LLC); magnesium oxide (MgO, CAS no. 1309-48-4; Sigma-Aldrich); and magnesium carbonate basic (CAS no. 39409-82-0; Sigma-Aldrich). All powders were sieved to achieve a particle size distribution between 25 and 75 μm.
Before testing, all powder samples were sterilized by heating to 180 °C for 3 h. (44)
Characterization of particle size was performed with a scanning electron microscope (Leo 1550 SEM; Zeiss, Oberkochen, Germany), operating at an acceleration voltage of 5 keV. Sieved powders were first sputter coated with a thin layer of gold/palladium to minimize charging effects.
Bacterial Strain
The bacterial strain Staphylococcus epidermidis (CCUG 18 000A) was used for all experiments. MH Broth (Sigma-Aldrich, Steinheim, Germany) was used to inoculate S. epidermidis overnight at 37 °C, after which the bacteria were centrifuged (1500g, 10 min, EBA 30 centrifuge; Hettich, Tuttlingen, Germany), collected, and resuspended in 250 μL of sterilized PBS (Product no P4417; Sigma-Aldrich). The concentration of bacteria was adjusted to an optical density (OD600) of 0.6 (UV spectrophotometer, UV-1800; Shimadzu), corresponding to approximately 6 × 108 CFU/mL.
MAA
Quantification of bacterial viability was performed using a MAA with resazurin as the fluorescent indicator. In the assay, blue nonfluorescent resazurin is reduced to pink, fluorescent resorufin by metabolic intermediates, resulting in fluorescence being a sensitive indicator of viable bacteria. (45)
To perform the MAA, wells in a 48-well plate were first filled with 200 μL of sterilized MH broth, 50 μL of resazurin solution at a concentration of 100 μg/mL, and 150 μL of PBS containing the sample to be tested. Immediately before viability testing, 100 μL of bacterial suspension in PBS at an OD of 0.06 was added to the well and thoroughly mixed with a pipette tip. The well plate was then placed in an orbital shaking incubator at 37 °C with shaking set to 250 rpm to limit settling of the particle samples and to increase bacteria–sample contact. At specific time points, the well plate was removed from the incubator, and fluorescence measurements were made in a microplate reader (Tecan Infinite M200), set to 530 nm excitation and 590 nm emission.
To check for linearity of the fluorescence readings with known concentrations of bacteria, three standard curves were recorded in parallel with each experiment. The standard curve consisted of a dilution series of nine wells containing 100 μL of bacterial suspension from OD = 0.06 to 0.003, 200 μL of sterilized MH broth, 200 μL of sterilized PBS, and resazurin at a concentration of 10 μg/mL.
Antibacterial Test
Suspensions of each powder to be tested (MMC, MgO, magnesium carbonate basic, and SBA-15) at a concentration of 1 mg/mL were used in the MAA for the antibacterial testing. Measurements were made in triplicate. Additionally, three wells containing each sample material, but without bacteria, were tested to determine the background fluorescence level of the MAA solutions/suspensions. Bacterial viability was determined as the difference in fluorescence levels between the wells with and without bacteria. Fluorescence measurements were made at 15, 30 min, and 1–3 h.
Recovery Test
To determine whether bacteria were permanently inactivated during the antibacterial test, a subsequent recovery test was performed where the bacteria were isolated from the sample powders and media used in the antibacterial test. This was accomplished by first allowing the powders to settle to the bottom of the wells for 5 min following the final fluorescence measurement after 3 h of bacteria–sample contact. Then, 100 μL of bacterial suspension from the upper half of each of the three sample wells was extracted and placed in a 1.5 mL centrifuge tube. The procedure was repeated for a second 1.5 mL centrifuge tube to which an additional 300 μL of ethanol was added to ensure that the bacteria were killed. For each sample material, both tubes were then centrifuged (1500g, 10 min, EBA 30 centrifuge; Hettich, Tuttlingen, Germany), and the supernatant was poured out. Bacteria were resuspended in MH broth and resazurin (10 μg/mL) and another MAA was performed with fluorescence measurements made at 1, 1.5, 2, and 2.5 h. The difference in fluorescence levels between the bacteria with and without added ethanol provided the viability of the bacteria after the antibacterial test when separated from the powder suspensions.
Effect of Media pH
The effect of pH on the growth of S. epidermidis was investigated by performing the MAA with media prepared at pH from 7.4 to 10.5, adjusted by the addition of NaOH. Six wells at each pH level were tested, three with bacteria and three without. The difference in fluorescence signal after 30 min of incubation at 37 °C provided the measure of bacterial viability.
Controlling for Effects of Media pH and Particles
An additional antibacterial test was performed using a concentrated PBS, with increased buffer capacity to maintain the pH at approximately 7.4 in the presence of the added powder samples. Additionally, to separate antibacterial effects due to contact with the particles themselves from the effects due to possible substances leached from the materials, testing of the media in which the sample powders had previously been soaked was carried out in parallel with testing of the media containing particles. Specifically, 100 mg of sample powder was added to 30 mL of 1.0 M PBS and placed in a tube rotator for 16 h. Subsequently, half of the suspension was centrifuged (1500g, 10 min, EBA 30 centrifuge; Hettich, Tuttlingen, Germany) and the supernatant was filtered through a 0.45 μm cellulose acetate membrane to remove any remaining particles. Both filtered PBS and PBS containing particle suspensions were tested using the MAA. When combined with the other constituents of the MAA, the resulting phosphate concentration was 0.3 M, and where applicable the particle concentration was 1 mg/mL. Three samples of both groups (filtered or particle-containing) of each material (MMC, MgO, or SBA-15) were tested with fluorescence readings made at 15, 30 min, 1–4 h. As in the Antibacterial section described above, additional three wells for both groups of each material, but without bacteria, were tested to determine the background fluorescence level of the MAA solutions/suspensions. Bacterial viability was determined as the difference in fluorescence levels between the wells with and without bacteria. Finally, pH measurements of the MAA solution containing the different sample powders were made at 0, 2, 3, and 4 h to determine any changes in the media pH.
Acknowledgment
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This work was supported by the Swedish Research Council (VR).
References
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- 6Wang, Z.; Carlsson, D. O.; Tammela, P.; Hua, K.; Zhang, P.; Nyholm, L.; Strømme, M. Surface Modified Nanocellulose Fibers Yield Conducting Polymer-Based Flexible Supercapacitors with Enhanced Capacitances ACS Nano 2015, 9, 7563– 71 DOI: 10.1021/acsnano.5b02846Google Scholar6Surface Modified Nanocellulose Fibers Yield Conducting Polymer-Based Flexible Supercapacitors with Enhanced CapacitancesWang, Zhaohui; Carlsson, Daniel O.; Tammela, Petter; Hua, Kai; Zhang, Peng; Nyholm, Leif; Stroemme, MariaACS Nano (2015), 9 (7), 7563-7571CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)It is demonstrated that surface modified nanocellulose fibers (NCFs) can be used as substrates to synthesize supercapacitor electrodes with the highest full electrode-normalized gravimetric (127 F g-1) and volumetric (122 F cm-3) capacitances at high current densities (300 mA cm-2 ≈ 33 A g-1) until date reported for conducting polymer-based electrodes with active mass loadings as high as 9 mg cm-2. By introducing quaternary amine groups on the surface of NCFs prior to polypyrrole (PPy) polymn., the macropore vol. of the formed PPy-NCF composites can be minimized while maintaining the vol. of the micro- and mesopores at the same level as when unmodified or carboxylate groups functionalized NCFs are employed as polymn. substrates. Sym., aq. electrolyte-based, devices comprising these porosity-optimized electrodes exhibit device-sp. volumetric energy and power densities of 3.1 mWh cm-3 and 3 W cm-3 resp.; which are among the highest values reported for conducting polymer electrodes in aq. electrolytes. The functionality of the devices is verified by powering a red light-emitting diode with the device in different mech. challenging states.
- 7Nakahara, K.; Oyaizu, K.; Nishide, H. Organic Radical Battery Approaching Practical Use Chem. Lett. 2011, 40, 222– 227 DOI: 10.1246/cl.2011.222Google Scholar7Organic radical battery approaching practical useNakahara, Kentaro; Oyaizu, Kenichi; Nishide, HiroyukiChemistry Letters (2011), 40 (3), 222-227CODEN: CMLTAG; ISSN:0366-7022. (Chemical Society of Japan)A review. The electrochem. redox reactions of org. polymers bearing robust unpaired electrons were investigated to det. the applicability of these polymers to rechargeable batteries. Such an "org. radical battery" would be environmentally friendly and have high-power characteristics. This highlight review describes the performance of a battery using a nitroxyl radical polymer as the cathode active material. The electron-transfer mechanism and recent developments that should lead to the practical application of the org. radical battery are also described.
- 8Wicki, A.; Witzigmann, D.; Balasubramanian, V.; Huwyler, J. Nanomedicine in cancer therapy: Challenges, opportunities, and clinical applications J. Controlled Release 2015, 200, 138– 157 DOI: 10.1016/j.jconrel.2014.12.030Google Scholar8Nanomedicine in cancer therapy: Challenges, opportunities, and clinical applicationsWicki, Andreas; Witzigmann, Dominik; Balasubramanian, Vimalkumar; Huwyler, JorgJournal of Controlled Release (2015), 200 (), 138-157CODEN: JCREEC; ISSN:0168-3659. (Elsevier B.V.)Cancer is a leading cause of death worldwide. Currently available therapies are inadequate and spur demand for improved technologies. Rapid growth in nanotechnol. towards the development of nanomedicine products holds great promise to improve therapeutic strategies against cancer. Nanomedicine products represent an opportunity to achieve sophisticated targeting strategies and multi-functionality. They can improve the pharmacokinetic and pharmacodynamic profiles of conventional therapeutics and may thus optimize the efficacy of existing anti-cancer compds. In this review, we discuss state-of-the-art nanoparticles and targeted systems that have been investigated in clin. studies. We emphasize the challenges faced in using nanomedicine products and translating them from a preclin. level to the clin. setting. Addnl., we cover aspects of nanocarrier engineering that may open up new opportunities for nanomedicine products in the clinic.
- 9Fadeel, B.; Kasemo, B.; Malmsten, M.; Strømme, M. Nanomedicine: reshaping clinical practice J. Intern. Med. 2010, 267, 2– 8 DOI: 10.1111/j.1365-2796.2009.02186.xGoogle Scholar9Nanomedicine: reshaping clinical practiceFadeel B; Kasemo B; Malmsten M; Stromme MJournal of internal medicine (2010), 267 (1), 2-8 ISSN:.There is no expanded citation for this reference.
- 10Mihranyan, A.; Ferraz, N.; Strømme, M. Current status and future prospects of nanotechnology in cosmetics Prog. Mater. Sci. 2012, 57, 875– 910 DOI: 10.1016/j.pmatsci.2011.10.001Google Scholar10Current status and future prospects of nanotechnology in cosmeticsMihranyan, Albert; Ferraz, Natalia; Stromme, MariaProgress in Materials Science (2012), 57 (5), 875-910CODEN: PRMSAQ; ISSN:0079-6425. (Elsevier Ltd.)A review. The cosmetics industry was among the first to implement nanotechnol. principles in product development. Of more than one thousand registered nanotechnol.-based products on the global market in 2009, more than 13% were classified as products for cosmetic use. In this review we highlight the most important scientific articles, expert opinions by regulatory authorities, and patent literature from Europe and the USA for the time period between 2000 and 2010 concerning the use of nanotechnol. in dermatol., dental, and haircare products intended for improving the appearance of the user. We present current and suggested uses of nanotechnol. in cosmetics with the main focus on nanomaterials as active substances, carriers and formulation aids. The new functionalities these materials are claimed to introduce are also described. We briefly discuss public opinion of nanotechnol. in general, and include the most important definitions related to this emerging technol. along with a summary of the general characteristics of nanoparticles and their safety aspects. The aim of the review is, thus, to provide an update on the current status and trends of research and industrial development related to the use of nanotechnol. in cosmetics and to give an indication of where the field could be heading in the future.
- 11Morry, J.; Ngamcherdtrakul, W.; Gu, S. D.; Goodyear, S. M.; Castro, D. J.; Reda, M. M.; Sangvanich, T.; Yantasee, W. Dermal delivery of HSP47 siRNA with NOX4-modulating mesoporous silica-based nanoparticles for treating fibrosis Biomaterials 2015, 66, 41– 52 DOI: 10.1016/j.biomaterials.2015.07.005Google Scholar11Dermal delivery of HSP47 siRNA with NOX4-modulating mesoporous silica-based nanoparticles for treating fibrosisMorry, Jingga; Ngamcherdtrakul, Worapol; Gu, Shenda; Goodyear, Shaun M.; Castro, David J.; Reda, Moataz M.; Sangvanich, Thanapon; Yantasee, WassanaBiomaterials (2015), 66 (), 41-52CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)Fibrotic diseases such as scleroderma have been linked to increased oxidative stress and upregulation of pro-fibrotic genes. Recent work suggests a role of NADPH oxidase 4 (NOX4) and heat shock protein 47 (HSP47) in inducing excessive collagen synthesis, leading to fibrotic diseases. Herein, we elucidate the relationship between NOX4 and HSP47 in fibrogenesis and propose to modulate them altogether as a new strategy to treat fibrosis. We developed a nanoparticle platform consisting of polyethylenimine (PEI) and polyethylene glycol (PEG) coating on a 50-nm mesoporous silica nanoparticle (MSNP) core. The nanoparticles effectively delivered small interfering RNA (siRNA) targeting HSP47 (siHSP47) in an in vitro model of fibrosis based on TGF-β stimulated fibroblasts. The MSNP core also imparted an antioxidant property by scavenging reactive oxygen species (ROS) and subsequently reducing NOX4 levels in the in vitro fibrogenesis model. The nanoparticle was far superior to n-acetyl cysteine (NAC) at modulating pro-fibrotic markers. In vivo evaluation was performed in a bleomycin-induced scleroderma mouse model, which shares many similarities to human scleroderma disease. Intradermal administration of siHSP47-nanoparticles effectively reduced HSP47 protein expression in skin to normal level. In addn., the antioxidant MSNP also played a prominent role in reducing the pro-fibrotic markers, NOX4, alpha smooth muscle actin (α-SMA), and collagen type I (COL I), as well as skin thickness of the mice.
- 12Kilpeläinen, M.; Riikonen, J.; Vlasova, M. A.; Huotari, A.; Lehto, V. P.; Salonen, J.; Herzig, K. H.; Järvinen, K. In vivo delivery of a peptide, ghrelin antagonist, with mesoporous silicon microparticles J. Controlled Release 2009, 137, 166– 70 DOI: 10.1016/j.jconrel.2009.03.017Google Scholar12In vivo delivery of a peptide, ghrelin antagonist, with mesoporous silicon microparticlesKilpelainen M; Riikonen J; Vlasova M A; Huotari A; Lehto V P; Salonen J; Herzig K H; Jarvinen KJournal of controlled release : official journal of the Controlled Release Society (2009), 137 (2), 166-70 ISSN:.Peptides may represent potential treatment options for many severe illnesses. However, they need an effective delivery system to overcome rapid degradation after their administration. One possible way to prolong peptide action is to use particulate drug delivery systems. In the present study, thermally hydrocarbonized mesoporous silicon (THCPSi) microparticles (38-53 microm) were studied as a peptide delivery system in vivo. D-lys-GHRP6 (ghrelin antagonist, GhA) was used as a model peptide. The effects of GhA-loaded THCPSi microparticles on food intake (s.c., GhA dose 14 mg/kg) and on blood pressure (s.c., GhA dose 4 mg/kg) were examined in mice and rats, respectively. In addition, the effects of THCPSi microparticles (2 mg) on cytokine secretion in mice after single s.c. administration were examined by determining several cytokine plasma concentrations. The present results demonstrate that GhA can be loaded into THCPSi microparticles with a high loading degree (20% w/w). GhA loaded THCPSi microparticles inhibited food intake for a prolonged time, and increased blood pressure more slowly than encountered with a GhA solution. Furthermore, THCPSi microparticles did not increase cytokine activity. The present results suggest that THCPSi might be used as a drug delivery system for peptides.
- 13Canham, L. Porous Silicon for Oral Hygiene and Cosmetics. In Handbook of Porous Silicon; Canham, L., Ed.; Springer International Publishing: Cham, 2014; pp 1– 8.Google ScholarThere is no corresponding record for this reference.
- 14Widenmeyer, M.; Anwander, R. Pore size control of highly ordered mesoporous silica MCM-48 Chem. Mater. 2002, 14, 1827– 1831 DOI: 10.1021/cm011273bGoogle ScholarThere is no corresponding record for this reference.
- 15Yamada, T.; Zhou, H. S.; Asai, K.; Honma, I. Pore size controlled mesoporous silicate powder prepared by triblock copolymer templates Mater. Lett. 2002, 56, 93– 96 DOI: 10.1016/S0167-577X(02)00424-XGoogle Scholar15Pore size controlled mesoporous silicate powder prepared by triblock copolymer templatesYamada, Takeo; Zhou, Haoshen; Asai, Keisuke; Honma, ItaruMaterials Letters (2002), 56 (1-2), 93-96CODEN: MLETDJ; ISSN:0167-577X. (Elsevier Science B.V.)The pore sizes of SBA-15 and SBA-16 were controlled well by the direct micelle control method, which was related with assembled conditions of the soln. temp. and concn. of the triblock copolymer. The relation between the pore size of the mesoporous silica and the assembled conditions is the same as that one among the core radius of the micelle triblock copolymer, the soln. temp. T, and the crit. micellization temp. Tc in ≈(T-Tc)0.2.
- 16Forsgren, J.; Frykstrand, S.; Grandfield, K.; Mihranyan, A.; Strømme, M. A Template-Free, Ultra-Adsorbing, High Surface Area Carbonate Nanostructure PLoS One 2013, 8e68486 DOI: 10.1371/journal.pone.0068486Google Scholar16A template-free, ultra-adsorbing, high surface area carbonate nanostructureForsgren, Johan; Frykstrand, Sara; Grandfield, Kathryn; Mihranyan, Albert; Stroemme, MariaPLoS One (2013), 8 (7), e68486CODEN: POLNCL; ISSN:1932-6203. (Public Library of Science)We report the template-free, low-temp. synthesis of a stable, amorphous, and anhyd. magnesium carbonate nanostructure with pore sizes below 6 nm and a sp. surface area of ∼800 m2 g-1, substantially surpassing the surface area of all previously described alkali earth metal carbonates. The moisture sorption of the novel nanostructure is featured by a unique set of properties including an adsorption capacity ∼50% larger than that of the hygroscopic zeolite-Y at low relative humidities and with the ability to retain more than 75% of the adsorbed water when the humidity is decreased from 95% to 5% at room temp. These properties can be regenerated by heat treatment at temps. below 100°C. The structure is foreseen to become useful in applications such as humidity control, as industrial adsorbents and filters, in drug delivery and catalysis.
- 17Frykstrand, S.; Forsgren, J.; Mihranyan, A.; Strømme, M. On the pore forming mechanism of Upsalite, a micro- and mesoporous magnesium carbonate Microporous Mesoporous Mater. 2014, 190, 99– 104 DOI: 10.1016/j.micromeso.2013.12.011Google ScholarThere is no corresponding record for this reference.
- 18Pochard, I.; Frykstrand, S.; Ahlström, O.; Forsgren, J.; Strømme, M. Water and ion transport in ultra-adsorbing porous magnesium carbonate studied by dielectric spectroscopy J. Appl. Phys. 2014, 115044306 DOI: 10.1063/1.4860276Google ScholarThere is no corresponding record for this reference.
- 19Pochard, I.; Frykstrand, S.; Eriksson, J.; Gustafsson, S.; Welch, K.; Strømme, M. Dielectric Spectroscopy Study of Water Behavior in Calcined Upsalite: A Mesoporous Magnesium Carbonate without Organic Surface Groups J. Phys. Chem. C 2015, 119, 15680– 15688 DOI: 10.1021/acs.jpcc.5b02370Google ScholarThere is no corresponding record for this reference.
- 20Zhang, P.; Forsgren, J.; Strømme, M. Stabilisation of amorphous ibuprofen in Upsalite, a mesoporous magnesium carbonate, as an approach to increasing the aqueous solubility of poorly soluble drugs Int. J. Pharm. 2014, 472, 185– 191 DOI: 10.1016/j.ijpharm.2014.06.025Google Scholar20Stabilisation of amorphous ibuprofen in Upsalite, a mesoporous magnesium carbonate, as an approach to increasing the aqueous solubility of poorly soluble drugsZhang, Peng; Forsgren, Johan; Stroemme, MariaInternational Journal of Pharmaceutics (Amsterdam, Netherlands) (2014), 472 (1-2), 185-191CODEN: IJPHDE; ISSN:0378-5173. (Elsevier B.V.)One attractive approach to increase the aq. soly. and thus the bioavailability of poorly sol. drugs is to formulate them in their amorphous state since amorphous compds. generally exhibit higher apparent solubilities than their cryst. counterparts. In the current work, mesoporous magnesium carbonate was used to stabilize the amorphous state of the model substance ibuprofen. Crystn. of the drug was completely suppressed in the formulation, resulting in both a higher apparent soly. and a three times faster dissoln. rate of the drug where the drug release was shown to be diffusion controlled. It was also shown that the formulation is stable for at least three months when stored at 75% relative humidity. The simple synthesis together with a high loading capacity and narrow pore size distribution of the mesoporous magnesium carbonate is foreseen to offer great advantages in formulations of poorly sol. drugs.
- 21Zhang, P.; Zardán Goméz De La Torre, T.; Forsgren, J.; Bergström, C. A. S.; Strømme, M. Diffusion-Controlled Drug Release from the Mesoporous Magnesium Carbonate Upsalite J. Pharm. Sci. 2016, 105, 657– 663 DOI: 10.1002/jps.24553Google Scholar21Diffusion-Controlled Drug Release from the Mesoporous Magnesium Carbonate UpsaliteZhang, Peng; Gomez De La Torre, Teresa Zardan; Forsgren, Johan; Bergstroem, Christel; Stromme, MariaJournal of Pharmaceutical Sciences (2016), 105 (2), 657-663CODEN: JPMSAE; ISSN:0022-3549. (Elsevier Inc.)In vitro drug release from well-defined particle-size fractions of the mesoporous magnesium carbonate material Upsalite was investigated in detail using ibuprofen, a biopharmaceutics classification system class II drug, as the model compd. The wt. of loaded drug corresponded to 30% of the wt. of the carrier and the pores were filled to approx. 80%. The incorporated ibuprofen was found to be in an amorphous state and was physisorbed, rather than chemisorbed, to the surfaces of the pore walls. In contrast to ibuprofen in mesoporous silica, there was no detectable drug on the outer surface of the carrier particles. Two ibuprofen doses were loaded into Upsalite particles with size fractions ranging from 25 μm to more than 200 μm. The initial release rate was controlled by the particle size; the dissoln. rate of the loaded ibuprofen during this period was more than four times faster than that of the cryst. drug. An extended-release period of about 24 h followed the initial rapid-release period. The features of this extended-release period were dependent on the total drug concn. in the release medium. Detailed anal. of the diffusion of ibuprofen in Upsalite provided the ibuprofen diffusion coeff. (9.8 × 10-8 cm2/s), the constrictivity of the diffusion process (0.47) and the tortuosity of the carrier (15). This relatively high tortuosity value indicates that Upsalite can be used not only to enhance the dissoln. rate of poorly sol. drugs but also as a carrier in sustained-release applications by using larger particle sizes or even pellets of the material. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Assocn. J Pharm Sci.
- 22Frykstrand, S.; Forsgren, J.; Zhang, P.; Strømme, M.; Ferraz, N. Cytotoxicity, in Vivo Skin Irritation and Acute Systemic Toxicity of the Mesoporous Magnesium Carbonate Upsalite J. Biomater. Nanobiotechnol. 2015, 6, 257– 266 DOI: 10.4236/jbnb.2015.64024Google ScholarThere is no corresponding record for this reference.
- 23Høiby, N.; Jarlov, J. O.; Kemp, M.; Tvede, M.; Bangsborg, J. M.; Kjerulf, A.; Pers, C.; Hansen, H. Excretion of ciprofloxacin in sweat and multiresistant Staphylococcus epidermidis Lancet 1997, 349, 167– 9 DOI: 10.1016/S0140-6736(96)09229-XGoogle ScholarThere is no corresponding record for this reference.
- 24Bek-Thomsen, M.; Lomholt, H. B.; Kilian, M. Acne is not associated with yet-uncultured bacteria J. Clin. Microbiol. 2008, 46, 3355– 60 DOI: 10.1128/JCM.00799-08Google Scholar24Acne is not associated with yet-uncultured bacteriaBek-Thomsen, M.; Lomholt, H. B.; Kilian, M.Journal of Clinical Microbiology (2008), 46 (10), 3355-3360CODEN: JCMIDW; ISSN:0095-1137. (American Society for Microbiology)Current clin. and microbiol. information on acne fails to demonstrate a clear assocn. between particular species, including Propionibacterium acnes, and disease, and the disease continues to be a considerable problem. To test if acne is assocd. with hitherto uncultured bacteria residing in diseased skin follicles, sequencing and phylogenetic anal. of approx. 5,700 amplified and cloned 16S rRNA genes were used to det. the microbial diversity in follicles from acne patients and healthy individuals and from the superficial skin of acne patients. Follicles from healthy skin were exclusively colonized by P. acnes, whereas the follicular microbiota of acne patients included, in addn., Staphylococcus epidermidis and minor proportions of other species. In comparison, samples from superficial skin showed a complex microbiota represented by 12 to 16 bacterial species. The findings of the study exclude the possibility that acne is assocd. with yet-uncultured bacteria and shows that healthy skin follicles constitute a remarkably exclusive habitat allowing colonization only by P. acnes.
- 25Makhluf, S.; Dror, R.; Nitzan, Y.; Abramovich, Y.; Jelinek, R.; Gedanken, A. Microwave-assisted synthesis of nanocrystalline MgO and its use as a bacteriocide Adv. Funct. Mater. 2005, 15, 1708– 1715 DOI: 10.1002/adfm.200500029Google Scholar25Microwave-assisted synthesis of nanocrystalline MgO and its use as a bactericideMakhluf, Shirly; Dror, Rachel; Nitzan, Yeshayahu; Abramovich, Yaniv; Jelinek, Raz; Gedanken, AharonAdvanced Functional Materials (2005), 15 (10), 1708-1715CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)Nanocryst. particles of MgO were synthesized using microwave radiation in an ethylene glycol soln. The antibacterial activities of the MgO nanoparticles were tested by treating Escherichia coli (Gram neg.) and Staphylococcus aureus (Gram pos.) cultures with 1 mg mL-1 of the nanoparticles. The authors have examd. the importance of the size effect, pH, and the form of the active MgO species as a bactericidal agent. A clear size dependence of the nanoparticles is obsd. where the amt. of eradicated bacteria was strongly dependent on the particle size.
- 26Pan, X.; Wang, Y.; Chen, Z.; Pan, D.; Cheng, Y.; Liu, Z.; Lin, Z.; Guan, X. Investigation of Antibacterial Activity and Related Mechanism of a Series of Nano-Mg(OH)2 ACS Appl. Mater. Interfaces 2013, 5, 1137– 1142 DOI: 10.1021/am302910qGoogle Scholar26Investigation of antibacterial activity and related mechanism of a series of nano-Mg(OH)2Pan, Xiaohong; Wang, Yonghao; Chen, Zhi; Pan, Danmei; Cheng, Yangjian; Liu, Zunjing; Lin, Zhang; Guan, XiongACS Applied Materials & Interfaces (2013), 5 (3), 1137-1142CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)The authors report the antibacterial effect and related mechanism of three nano-Mg(OH)2 slurries using Escherichia coli as model bacteria. X-ray diffraction (XRD), SEM and laser particle size anal. revealed that the as-synthesized Mg(OH)2_MgCl2, Mg(OH)2_MgSO4 and Mg(OH)2_MgO are all composed by nanoflakes with different sizes, and their aggregates in water are 5.5, 4.5, and 1.2 μm, resp. Bactericidal tests showed that the antibacterial efficiency is conversely correlated with the size of Mg(OH)2 aggregates. Transmission electron microscopy (TEM) observation have not provided evidence of cellular internalization, however, the antibacterial effect is pos. correlation to the loss of integrity of cell walls. SEM and zeta potential anal. revealed that the adhering ability of Mg(OH)2 on the bacterial surface is Mg(OH)2_MgCl2 > Mg(OH)2_MgSO4 > Mg(OH)2_MgO, indicating the toxicity of Mg(OH)2 may be caused by the electrostatic interaction-induced external adsorption. Confocal laser scanning microscopy (CLSM) further revealed that the adhering of Mg(OH)2 on the bacterial surface could increase the permeability of cell membranes. Thus, the antibacterial mechanism of nano-Mg(OH)2 could be as follows: nano-Mg(OH)2 adsorbed on the bacterial surface by charge attraction first, and then destroying the integrity of cell walls, resulting in the final death of bacteria.
- 27Stoimenov, P. K.; Klinger, R. L.; Marchin, G. L.; Klabunde, K. J. Metal oxide nanoparticles as bactericidal agents Langmuir 2002, 18, 6679– 6686 DOI: 10.1021/la0202374Google Scholar27Metal Oxide Nanoparticles as Bactericidal AgentsStoimenov, Peter K.; Klinger, Rosalyn L.; Marchin, George L.; Klabunde, Kenneth J.Langmuir (2002), 18 (17), 6679-6686CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Reactive magnesium oxide nanoparticles and halogen (Cl2, Br2) adducts of these MgO particles were allowed to contact certain bacteria and spore cells. Bacteriol. test data, at. force microscopy (AFM) images, and electron microscopy (TEM) images are provided, which yield insight into the biocidal action of these nanoscale materials. The tests show that these materials are very effective against Gram-pos. and Gram-neg. bacteria as well as spores. ζ-Potential measurements show an attractive interaction between the MgO nanoparticles and bacteria and spore cells, which is confirmed by confocal microscopy images. The AFM studies illustrate considerable changes in the cell membranes upon treatment, resulting in the death of the cells. TEM micrographs confirm these results and supply addnl. information about the processes inside the cells. Overall, the results presented illustrate that dry powder nanoparticulate formulations as well as water slurries are effective. It is proposed that abrasiveness, basic character, electrostatic attraction, and oxidizing power (due to the presence of active halogen) combine to promote these biocidal properties.
- 28Sawai, J.; Kojima, H.; Igarashi, H.; Hashimoto, A.; Shoji, S.; Takehara, A.; Sawaki, T.; Kokugan, T.; Shimizu, M. Escherichia coli damage by ceramic powder slurries J. Chem. Eng. Jpn. 1997, 30, 1034– 1039 DOI: 10.1252/jcej.30.1034Google Scholar28Escherichia coli damage by ceramic powder slurriesSawai, Jun; Kojima, Hiromitsu; Igarashi, Hideo; Hashimoto, Atsushi; Shoji, Shinorbu; Takehara, Akemi; Sawaki, Takashi; Kokugan, Takao; Shimizu, MasaruJournal of Chemical Engineering of Japan (1997), 30 (6), 1034-1039CODEN: JCEJAQ; ISSN:0021-9592. (Society of Chemical Engineers, Japan)To elucidate the antibacterial mechanisms of the ceramics magnesium oxide (MgO), calcium oxide (CaO) and zinc oxide (ZnO), damage to bacteria caused by these powder slurries are studied on the basis of change in sensitivities to antibiotics, of which the primary inhibitory actions are understood well. Four kinds of antibiotics, penicillin G, chloramphenicol, nalidixic acid and rifampicin, were used as the selective reagents. The MgO and CaO powder slurries increased the sensitivities of Escherichia coli to rifampicin and chloramphenicol. Though the MgO and CaO powder slurries have high pH values, changes in the sensitivities by the MgO and CaO powder slurries were obviously different from those via alk. treatment. The ZnO powder slurry enhanced the sensitivity of the E. coli to chloramphenicol. This result suggests that the antibacterial actions of MgO and CaO powder slurries were different from those of ZnO powder slurry.
- 29Yamamoto, O.; Sawai, J.; Sasamoto, T. Change in antibacterial characteristics with doping amount of ZnO in MgO-ZnO solid solution Int. J. Inorg. Mater. 2000, 2, 451– 454 DOI: 10.1016/S1466-6049(00)00045-3Google Scholar29Change in antibacterial characteristics with doping amount of ZnO in MgO-ZnO solid solutionYamamoto, Osamu; Sawai, Jun; Sasamoto, TadashiInternational Journal of Inorganic Materials (2000), 2 (5), 451-454CODEN: IJIMCR; ISSN:1466-6049. (Elsevier Science Ltd.)Antibacterial activity for MgO-ZnO solid soln. was studied by measuring the change in elec. cond. with bacterial growth. MgO-ZnO solid soln. powders were prepd. by heating at 1400°C for 3 h in air. A single phase with cubic type structure was obtained in the wt. ratio range (MgO/ZnO) of 4.0 and 1.5, but the ratio of 0.67 resulted in a ZnO phase in addn. to solid soln. After milling the solid soln. powders by planetary ball mill, the av. particle size and the sp. surface area of these powders became 0.1 μm and 26 m2/g, resp., which were used in the test of antibacterial activity. From the results of antibacterial tests, the activity increased with increasing the powder concn. in the medium. With increasing the doping amt. of ZnO in MgO-ZnO solid soln., it was found to show a decrease in the antibacterial activity against Escherichia coli and Staphylococcus aureus. The pH value in physiol. saline at the powder concn. of 2.5 mg/mL showed the alkali region above 10.0, and decreased with the increase of ZnO amt. in solid soln. The decrease in antibacterial activity, therefore, was assocd. with the decrease of pH value in medium.
- 30Hewitt, C. J.; Bellara, S. R.; Andreani, A.; Nebe-Von-Caron, G.; McFarlane, C. M. An evaluation of the anti-bacterial action of ceramic powder slurries using multi-parameter flow cytometry Biotechnol. Lett. 2001, 23, 667– 675 DOI: 10.1023/A:1010379714673Google Scholar30An evaluation of the antibacterial action of ceramic powder slurries using multi-parameter flow cytometryHewitt, Christopher J.; Bellara, Sanjay R.; Andreani, Andrea; Nebe-Von-Caron, Gerhard; McFarlane, Caroline M.Biotechnology Letters (2001), 23 (9), 667-675CODEN: BILED3; ISSN:0141-5492. (Kluwer Academic Publishers)Multi-parameter flow cytometric techniques have been used to study the effects of three ceramic powders CaO, MgO and ZnO on the physiol. of individual, exponentially growing E. coli cells. While all three powders inhibited reproductive growth, depending on their concn., the mechanism of action of CaO and MgO was different to that of ZnO as shown by fluorescent staining techniques developed in our lab.
- 31Huang, L.; Li, D.; Lin, Y.; Evans, D. G.; Duan, X. Influence of nano-MgO particle size on bactericidal action against Bacillus subtilis var. niger Chin. Sci. Bull. 2005, 50, 514– 519 DOI: 10.1007/BF02897474Google Scholar31Influence of nano-MgO particle size on bactericidal action against Bacillus subtilis var. nigerHuang, Lei; Li, Dianqing; Lin, Yanjun; Evans, David G.; Duan, XueChinese Science Bulletin (2005), 50 (6), 514-519CODEN: CSBUEF; ISSN:1001-6538. (Science in China Press)Nano-MgO with various particle sizes, synthesized by different methods using Mg(NO3)2·6H2O, Na2CO3, Na2SO4, urea and ammonia soln. as reactants, was used to carry out bactericidal expts. on Bacillus subtilis var. niger. The results were compared with the effect of TiO2, a common kind of photocatalytic material. The materials were characterized by X-ray diffraction, transmission electron microscopy, low temp. N2 adsorption-desorption measurements and FT-IR, and the results showed that the bactericidal ability of MgO increases with decreasing particle size. Nano-MgO and an interior wall-paint contg. the material have better bactericidal effects than nano-TiO2 in both presence and absence of light. The bactericidal mechanism is discussed. The surface of MgO can generate high concns. of O2- which is highly active and can react with the peptide linkages in the coating walls of the spores. The spores are destroyed by the resulting damage to their structure.
- 32Huang, L.; Li, D. Q.; Lin, Y. J.; Wei, M.; Evans, D. G.; Duan, X. Controllable preparation of Nano-MgO and investigation of its bactericidal properties J. Inorg. Biochem. 2005, 99, 986– 993 DOI: 10.1016/j.jinorgbio.2004.12.022Google Scholar32Controllable preparation of Nano-MgO and investigation of its bactericidal propertiesHuang, Lei; Li, Dian-Qing; Lin, Yan-Jun; Wei, Min; Evans, David G.; Duan, XueJournal of Inorganic Biochemistry (2005), 99 (5), 986-993CODEN: JIBIDJ; ISSN:0162-0134. (Elsevier B.V.)Samples of nano-MgO with varying particle sizes were prepd. by four different methods using Mg(NO3)2·6H2O, Na2CO3, urea and NH3 as raw materials and characterized by XRD, TEM, low temp. N2 adsorption-desorption measurements and FTIR spectroscopy. Bactericidal expts. with Bacillus subtilis var. niger and Staphylococcus aureus were carried out using as-synthesized nano-MgO samples and the bactericidal mechanism was also studied. The bactericidal efficacy of nano-MgO increases with decreasing particle size. The bactericidal efficacy of the samples was compared with that of TiO2, a common photoactive bactericidal material. The nano-MgO has better bactericidal activity, both when used directly and as an additive in an interior wall paint. Also, nano-MgO is active even in the absence of irradn.
- 33Krishnamoorthy, K.; Manivannan, G.; Kim, S. J.; Jeyasubramanian, K.; Premanathan, M. Antibacterial activity of MgO nanoparticles based on lipid peroxidation by oxygen vacancy J. Nanopart. Res. 2012, 141063 DOI: 10.1007/s11051-012-1063-6Google Scholar33Antibacterial activity of MgO nanoparticles based on lipid peroxidation by oxygen vacancyKrishnamoorthy, Karthikeyan; Manivannan, Govindasamy; Kim, Sang Jae; Jeyasubramanian, Kadarkaraithangam; Premanathan, MariappanJournal of Nanoparticle Research (2012), 14 (9), 1063/1-1063/10CODEN: JNARFA; ISSN:1388-0764. (Springer)Antibacterial activity of MgO nanoparticles (NPs) was evaluated against the Gram-neg. bacteria Escherichia coli and Pseudomonas aeruginosa as well as the Gram-pos. bacterium Staphylococcus aureus by microtitre plate-based assay incorporating resazurin as an indicator of cell growth. MgO NPs exhibited antibacterial activity with minimal inhibitory concn. of 500 μg/mL against E. coli and 1,000 μg/mL for P. aeruginosa and S. aureus. MgO NPs enhanced ultrasound-induced lipid peroxidn. in the liposomal membrane. The mechanism of the antibacterial activity of the MgO NPs relied on the presence of defects or oxygen vacancy at the surface of the nanoparticle which led to the lipid peroxidn. and reactive oxygen species generation.
- 34Yamamoto, O.; Fukuda, T.; Kimata, M.; Sawai, J.; Sasamoto, T. Antibacterial characteristics of MgO-mounted spherical carbons prepared by carbonization of ion-exchanged resin J. Ceram. Soc. Jpn. 2001, 109, 363– 365 DOI: 10.2109/jcersj.109.1268_363Google Scholar34Antibacterial characteristics of MgO-mounted spherical carbons prepared by carbonization of ion-exchanged resinYamamoto, Osamu; Fukuda, Taiki; Kimata, Mitsumasa; Sawai, Jun; Sasamoto, TadashiJournal of the Ceramic Society of Japan (2001), 109 (April), 363-365CODEN: JCSJEW; ISSN:0914-5400. (Ceramic Society of Japan)Ion-exchange resins with particle size of 0.5 mm were treated by an aq. soln. of MgSO4 and then they were carbonized for 1 h in nitrogen gas at 300-1000°C. The amt. of MgO in the carbon samples was ∼30 wt.%, irresp. of carbonization temp. The antibacterial activity of carbon samples contg. MgO was examd. by the colony count method. The pH values in physiol. saline dispersed within carbon samples were in the range of 9.4-9.8, but the values did not affect the occurrence of antibacterial activity. From the antibacterial tests, it was found that the antibacterial activity for Escherichia coli and Staphylococcus aureus on carbon samples contg. MgO increased with increasing carbonization temp. of the ion-exchanged resin.
- 35Yamamoto, O.; Ohira, T.; Alvarez, K.; Fukuda, M. Antibacterial characteristics of CaCO3-MgO composites Mater. Sci. Eng. B 2010, 173, 208– 212 DOI: 10.1016/j.mseb.2009.12.007Google Scholar35Antibacterial characteristics of CaCO3-MgO compositesYamamoto, Osamu; Ohira, Toshiaki; Alvarez, Kelly; Fukuda, MasayukiMaterials Science & Engineering, B: Advanced Functional Solid-State Materials (2010), 173 (1-3), 208-212CODEN: MSBTEK; ISSN:0921-5107. (Elsevier B.V.)Dentifrices, such as tooth-paste, are pastes contg. insol. abrasives that aid in the removal of plaque from the teeth and help to polish them. Composite powders contributing to oral hygiene application, i.e., nano-scale MgO crystallite dispersed in CaCO3 grain, were fabricated by the thermal decompn. of dolomite. The composite obtained by heating at 800 °C consisted of CaCO3 grains including 20 nm MgO fine crystallite, being the purpose powder in this study. The antibacterial activity of these powders related to gram-pos. and gram-neg. bacteria was evaluated in vitro. The thermal decompn. above 800 °C resulted in the mixt. of CaO and MgO. Antibacterial activity of the composite enhanced with increasing powder concn. Though antibacterial action toward Staphylococcus aureus was greater than towards Escherichia coli, the death rate const. was identical in both bacteria. It can be concluded that the obtained composite possesses two functions able to improve the oral hygiene: as a tooth abrasive and as an antibacterial agent.
- 36Sawai, J.; Kojima, H.; Igarashi, H.; Hashimoto, A.; Shoji, S.; Sawaki, T.; Hakoda, A.; Kawada, E.; Kokugan, T.; Shimizu, M. Antibacterial characteristics of magnesium oxide powder World J. Microbiol. Biotechnol. 2000, 16, 187– 194 DOI: 10.1023/A:1008916209784Google Scholar36Antibacterial characteristics of magnesium oxide powderSawai, J.; Kojima, H.; Igarashi, H.; Hashimoto, A.; Shoji, S.; Sawaki, T.; Hakoda, A.; Kawada, E.; Kokugan, T.; Shimizu, M.World Journal of Microbiology & Biotechnology (2000), 16 (2), 187-194CODEN: WJMBEY; ISSN:0959-3993. (Kluwer Academic Publishers)The antibacterial activity of magnesium oxide (MgO) was studied. Inhibitory zones appeared around the MgO powder slurry put directly on nutrient agar plates seeded with Escherichia coli or Staphylococcus aureus. However, no zone was obsd. using a penicillin cup to avoid contact between the bacteria and the MgO powder. Moreover, the supernatant soln. of the MgO powder slurry and a MgCl2 soln. contg. Mg2+ at a concn. of the soly. of MgO did not affect the growth of E. coli and S. aureus. Moreover, elevated shaking speed increased the death of E. coli in the slurry, indicating that the contact frequency between bacterial cells and MgO powders affected the antibacterial activity. It was considered that the contact between MgO powder and bacteria was important for the occurrence of its antibacterial activity. Since the generation of active oxygen, such as O2, from the MgO powder slurry was detected by chemiluminescence anal., an investigation was carried out to det. whether active oxygen generated from MgO powder slurry was related to its antibacterial activity. The changes in the antibiotic sensitivity in E. coli treated by MgO powder agreed with those by active oxygen treatment. These results suggested that the active oxygen generated from the MgO powder slurry was one of the primary factors in its antibacterial activity.
- 37Sawai, J.; Shiga, H.; Kojima, H. Kinetic analysis of death of bacteria in CaO powder slurry Int. Biodeterior. Biodegrad. 2001, 47, 23– 26 DOI: 10.1016/S0964-8305(00)00115-3Google Scholar37Kinetic analysis of death of bacteria in CaO powder slurrySawai, J.; Shiga, H.; Kojima, H.International Biodeterioration & Biodegradation (2001), 47 (1), 23-26CODEN: IBBIES; ISSN:0964-8305. (Elsevier Science Ltd.)The process of Escherichia coli and Staphylococcus aureus death in CaO powder slurry was assumed to follow 1st-order reaction kinetics. The apparent death rate const. (k) increased with increasing powder concn. and was higher than that for a NaOH soln. having the same pH as the CaO powder slurry. The slurry temp. significantly affected the bactericidal action of the CaO powder slurry against both E. coli and S. aureus. The slope of the Arrhenius plot of k for both bacteria changed at a slurry temp. of ∼22°, suggested to correspond to a change in the activation energy required to induce the death of bacteria in CaO powder slurry as a result of a phase transition of the cell membrane.
- 38Rawlinson, L. A.; O’Gara, J. P.; Jones, D. S.; Brayden, D. J. Resistance of Staphylococcus aureus to the cationic antimicrobial agent poly(2-(dimethylamino ethyl)methacrylate) (pDMAEMA) is influenced by cell-surface charge and hydrophobicity J. Med. Microbiol. 2011, 60, 968– 76 DOI: 10.1099/jmm.0.025619-0Google Scholar38Resistance of Staphylococcus aureus to the cationic antimicrobial agent poly(2-(dimethylamino ethyl)methacrylate) (pDMAEMA) is influenced by cell-surface charge and hydrophobicityRawlinson Lee-Anne B; O'Gara James P; Jones David S; Brayden David JJournal of medical microbiology (2011), 60 (Pt 7), 968-76 ISSN:.Cationic antimicrobial agents may prevent device-associated infections caused by Staphylococcus epidermidis and Staphylococcus aureus. This study reports that the cationic antimicrobial polymer poly(2-(dimethylamino ethyl)methacrylate) (pDMAEMA) was more effective at antagonizing growth of clinical isolates of S. epidermidis than of S. aureus. Importantly, mature S. epidermidis biofilms were significantly inactivated by pDMAEMA. The S. aureus isolates tested were generally more hydrophobic than the S. epidermidis isolates and had a less negative charge, although a number of individual S. aureus and S. epidermidis clinical isolates had similar surface hydrophobicity and charge values. Fluorescence spectroscopy and flow cytometry revealed that fluorescently labelled pDMAEMA interacted strongly with S. epidermidis compared with S. aureus. S. aureus ΔdltA and ΔmprF mutants were less hydrophobic and therefore more susceptible to pDMAEMA than wild-type S. aureus. Although the different susceptibility of S. epidermidis and S. aureus isolates to pDMAEMA is complex, influenced in part by surface hydrophobicity and charge, these findings nevertheless reveal the potential of pDMAEMA to treat S. epidermidis infections.
- 39Carter, C. B.; Norton, M. G. Coatings and Thick Films. In Ceramic Materials: Science and Engineering, 2nd ed.; Springer Science+Business Media: New York, 2013; p 502.Google ScholarThere is no corresponding record for this reference.
- 40Gence, N.; Ozbay, N. pH dependence of electrokinetic behavior of dolomite and magnesite in aqueous electrolyte solutions Appl. Surf. Sci. 2006, 252, 8057– 8061 DOI: 10.1016/j.apsusc.2005.10.015Google ScholarThere is no corresponding record for this reference.
- 41Vinu, A.; Murugesan, V.; Hartmann, M. Adsorption of lysozyme over mesoporous molecular sieves MCM-41 and SBA-15: Influence of pH and aluminum incorporation J. Phys. Chem. B 2004, 108, 7323– 7330 DOI: 10.1021/jp037303aGoogle ScholarThere is no corresponding record for this reference.
- 42Unosson, E.; Morgenstern, M.; Engqvist, H.; Welch, K. In vitro antibacterial properties and UV induced response from Staphylococcus epidermidis on Ag/Ti oxide thin films J. Mater. Sci.: Mater. Med. 2016, 27, 49 DOI: 10.1007/s10856-015-5662-5Google Scholar42In vitro antibacterial properties and UV induced response from Staphylococcus epidermidis on Ag/Ti oxide thin filmsUnosson Erik; Morgenstern Matthias; Engqvist Hakan; Welch KenJournal of materials science. Materials in medicine (2016), 27 (3), 49 ISSN:.Implanted materials are susceptible to bacterial colonization and biofilm formation, which can result in severe infection and lost implant function. UV induced photocatalytic disinfection on TiO2 and release of Ag(+) ions are two promising strategies to combat such events, and can be combined for improved efficiency. In the current study, a combinatorial physical vapor deposition technique was utilized to construct a gradient coating between Ag and Ti oxide, and the coating was evaluated for antibacterial properties in darkness and under UV light against Staphylococcus epidermidis. The findings revealed a potent antibacterial effect in darkness due to Ag(+) release, with near full elimination (97%) of viable bacteria and visible cell lysis on Ag dominated surfaces. The photocatalytic activity, however, was demonstrated poor due to low TiO2 crystallinity, and UV light irradiation of the coating did not contribute to the antibacterial effect. On the contrary, bacterial viability was in several instances higher after UV illumination, proposing a UV induced SOS response from the bacteria that limited the reduction rate during Ag(+) exposure. Such secondary effects should thus be considered in the development of multifunctional coatings that rely on UV activation.
- 43Heikkilä, T.; Santos, H. A.; Kumar, N.; Murzin, D. Y.; Salonen, J.; Laaksonen, T.; Peltonen, L.; Hirvonen, J.; Lehto, V. P. Cytotoxicity study of ordered mesoporous silica MCM-41 and SBA-15 microparticles on Caco-2 cells Eur. J. Pharm. Biopharm. 2010, 74, 483– 494 DOI: 10.1016/j.ejpb.2009.12.006Google Scholar43Cytotoxicity study of ordered mesoporous silica MCM-41 and SBA-15 microparticles on Caco-2 cellsHeikkila Teemu; Santos Helder A; Kumar Narendra; Murzin Dmitry Yu; Salonen Jarno; Laaksonen Timo; Peltonen Leena; Hirvonen Jouni; Lehto Vesa-PekkaEuropean journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V (2010), 74 (3), 483-94 ISSN:.Cytotoxicity of ordered mesoporous silica MCM-41 and SBA-15 microparticles (fractions between 1 and 160 microm) was determined in vitro on undifferentiated human colon carcinoma (Caco-2) cell line, considering the feasibility of using these silica-based materials in oral drug formulations. The cellular endpoints employed for assessing the effects of the MCM-41 and SBA-15 microparticles on Caco-2 were: (1) cell membrane integrity by monitoring live-cell protease activity (AFC) and by employing the flow cytometry method; (2) metabolic activity by monitoring total ATP content via luminescence assay; (3) activity of apoptotic effectors by caspase-3/7 activity assay. The generation of reactive oxygen species (ROS) was also followed, specifically the hydrogen peroxide (H(2)O(2)) and the superoxide radical (O(2)(-)). MCM-41 and SBA-15 microparticles caused cytotoxic effects on the Caco-2 cells, at most tested concentrations (0.2-14 mg/ml) and incubation times (3 and 24h). The effects on the cells included weakened cell membrane integrity, diminished cell metabolism and increased apoptotic signalling. The root cause for the cytotoxicity was heightened production of reactive oxygen species (ROS), especially the formation of the superoxide radical O(2)(-) already after 3h incubation with threshold dose 1mg/ml, apparently overwhelming the antioxidant defences and causing mitochondrial dysfunction, hence increasing the apoptotic signalling.
- 44WHO. Essential Medicines and Health Products, Methods of Sterilization. In The International Pharmacopoeia, 5th ed. [Online]; WHO, 2015. http://apps.who.int/phint/alt/index.html#d/b.7.5.9 (accessed Sept 1, 2016).Google ScholarThere is no corresponding record for this reference.
- 45Sarker, S. D.; Nahar, L.; Kumarasamy, Y. Microtitre plate-based antibacterial assay incorporating resazurin as an indicator of cell growth, and its application in the in vitro antibacterial screening of phytochemicals Methods 2007, 42, 321– 4 DOI: 10.1016/j.ymeth.2007.01.006Google Scholar45Microtitre plate-based antibacterial assay incorporating resazurin as an indicator of cell growth, and its application in the in vitro antibacterial screening of phytochemicalsSarker, Satyajit D.; Nahar, Lutfun; Kumarasamy, YashodharanMethods (Oxford, United Kingdom) (2007), 42 (4), 321-324CODEN: MTHDE9; ISSN:1046-2023. (Elsevier Ltd.)The resazurin assay utilizing microtitre-plate, described by Drummond and Waigh in 2000, has been modified to achieve more accuracy in the detn. of the min. inhibitory concn. (MIC) values of natural products, including crude exts., chromatog. fractions or purified compds. against various bacterial strains. This modified resazurin method is simple, sensitive, rapid, robust and reliable, and could be used successfully to assess antibacterial properties of natural products.
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Abstract
Figure 1
Figure 1. SEM images of a sieved sample particle of (a) MMC, (b) MgO, (c) SBA-15, and (d) magnesium carbonate basic.
Figure 2
Figure 2. Viability measurements as a function of time for bacteria in contact with MMC, magnesium oxide, mesoporous silica, and magnesium carbonate basic in comparison to the negative control PBS. Solid lines are guides to the eye, whereas the dashed line represents an exponential fit to the data for PBS. Data represent mean ± 1 sd for n = 3.
Figure 3
Figure 3. Fluorescence measurements showing the growth of bacteria suspensions after separation from the powder samples at the end of the antibacterial test. The legend indicates which sample powder the bacteria had previously been in contact with. Lines represent exponential fits to the data, with corresponding equations provided in the top left corner of the plot.
Figure 4
Figure 4. Relative viability of bacterial suspensions at pH ranging from 7.4 to 10.54, referenced to the viability of the unadjusted media at pH = 7.4. Data represent mean ± 1 sd for n = 3.
Figure 5
Figure 5. Viability measurements as a function of time for bacteria in contact with MMC, magnesium oxide, and mesoporous silica in concentrated PBS (phosphate concentration 0.3 M). A negative control without powder (denoted PBS) is provided for comparison. Solid lines are provided as guides to the eye. Data represent mean ± 1 sd for n = 3.
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- 5Nyholm, L.; Nyström, G.; Mihranyan, A.; Strømme, M. Toward Flexible Polymer and Paper-Based Energy Storage Devices Adv. Mater. 2011, 23, 3751– 3769 DOI: 10.1002/adma.2010041345Toward Flexible Polymer and Paper-Based Energy Storage DevicesNyholm, Leif; Nystroem, Gustav; Mihranyan, Albert; Stromme, MariaAdvanced Materials (Weinheim, Germany) (2011), 23 (33), 3751-3769CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review of recent progress concerning the development of flexible energy storage devices based on electronically conducting polymers and cellulose contg. composites with particular emphasis on paper-based batteries and supercapacitors. All-polymer and paper-based energy storage devices have significant inherent advantages in comparison with many currently employed batteries and supercapacitors regarding environmental friendliness, flexibility, cost and versatility. The research within this field is currently undergoing an exciting development as new polymers, composites and paper-based devices are being developed. Recent progress in the development of the most commonly used electronically conducting polymers used in flexible device prototypes, the advantages and disadvantages of this type of energy storage devices, as well as the 2 main approaches used in the manufg. of paper-based charge storage devices, are discussed.
- 6Wang, Z.; Carlsson, D. O.; Tammela, P.; Hua, K.; Zhang, P.; Nyholm, L.; Strømme, M. Surface Modified Nanocellulose Fibers Yield Conducting Polymer-Based Flexible Supercapacitors with Enhanced Capacitances ACS Nano 2015, 9, 7563– 71 DOI: 10.1021/acsnano.5b028466Surface Modified Nanocellulose Fibers Yield Conducting Polymer-Based Flexible Supercapacitors with Enhanced CapacitancesWang, Zhaohui; Carlsson, Daniel O.; Tammela, Petter; Hua, Kai; Zhang, Peng; Nyholm, Leif; Stroemme, MariaACS Nano (2015), 9 (7), 7563-7571CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)It is demonstrated that surface modified nanocellulose fibers (NCFs) can be used as substrates to synthesize supercapacitor electrodes with the highest full electrode-normalized gravimetric (127 F g-1) and volumetric (122 F cm-3) capacitances at high current densities (300 mA cm-2 ≈ 33 A g-1) until date reported for conducting polymer-based electrodes with active mass loadings as high as 9 mg cm-2. By introducing quaternary amine groups on the surface of NCFs prior to polypyrrole (PPy) polymn., the macropore vol. of the formed PPy-NCF composites can be minimized while maintaining the vol. of the micro- and mesopores at the same level as when unmodified or carboxylate groups functionalized NCFs are employed as polymn. substrates. Sym., aq. electrolyte-based, devices comprising these porosity-optimized electrodes exhibit device-sp. volumetric energy and power densities of 3.1 mWh cm-3 and 3 W cm-3 resp.; which are among the highest values reported for conducting polymer electrodes in aq. electrolytes. The functionality of the devices is verified by powering a red light-emitting diode with the device in different mech. challenging states.
- 7Nakahara, K.; Oyaizu, K.; Nishide, H. Organic Radical Battery Approaching Practical Use Chem. Lett. 2011, 40, 222– 227 DOI: 10.1246/cl.2011.2227Organic radical battery approaching practical useNakahara, Kentaro; Oyaizu, Kenichi; Nishide, HiroyukiChemistry Letters (2011), 40 (3), 222-227CODEN: CMLTAG; ISSN:0366-7022. (Chemical Society of Japan)A review. The electrochem. redox reactions of org. polymers bearing robust unpaired electrons were investigated to det. the applicability of these polymers to rechargeable batteries. Such an "org. radical battery" would be environmentally friendly and have high-power characteristics. This highlight review describes the performance of a battery using a nitroxyl radical polymer as the cathode active material. The electron-transfer mechanism and recent developments that should lead to the practical application of the org. radical battery are also described.
- 8Wicki, A.; Witzigmann, D.; Balasubramanian, V.; Huwyler, J. Nanomedicine in cancer therapy: Challenges, opportunities, and clinical applications J. Controlled Release 2015, 200, 138– 157 DOI: 10.1016/j.jconrel.2014.12.0308Nanomedicine in cancer therapy: Challenges, opportunities, and clinical applicationsWicki, Andreas; Witzigmann, Dominik; Balasubramanian, Vimalkumar; Huwyler, JorgJournal of Controlled Release (2015), 200 (), 138-157CODEN: JCREEC; ISSN:0168-3659. (Elsevier B.V.)Cancer is a leading cause of death worldwide. Currently available therapies are inadequate and spur demand for improved technologies. Rapid growth in nanotechnol. towards the development of nanomedicine products holds great promise to improve therapeutic strategies against cancer. Nanomedicine products represent an opportunity to achieve sophisticated targeting strategies and multi-functionality. They can improve the pharmacokinetic and pharmacodynamic profiles of conventional therapeutics and may thus optimize the efficacy of existing anti-cancer compds. In this review, we discuss state-of-the-art nanoparticles and targeted systems that have been investigated in clin. studies. We emphasize the challenges faced in using nanomedicine products and translating them from a preclin. level to the clin. setting. Addnl., we cover aspects of nanocarrier engineering that may open up new opportunities for nanomedicine products in the clinic.
- 9Fadeel, B.; Kasemo, B.; Malmsten, M.; Strømme, M. Nanomedicine: reshaping clinical practice J. Intern. Med. 2010, 267, 2– 8 DOI: 10.1111/j.1365-2796.2009.02186.x9Nanomedicine: reshaping clinical practiceFadeel B; Kasemo B; Malmsten M; Stromme MJournal of internal medicine (2010), 267 (1), 2-8 ISSN:.There is no expanded citation for this reference.
- 10Mihranyan, A.; Ferraz, N.; Strømme, M. Current status and future prospects of nanotechnology in cosmetics Prog. Mater. Sci. 2012, 57, 875– 910 DOI: 10.1016/j.pmatsci.2011.10.00110Current status and future prospects of nanotechnology in cosmeticsMihranyan, Albert; Ferraz, Natalia; Stromme, MariaProgress in Materials Science (2012), 57 (5), 875-910CODEN: PRMSAQ; ISSN:0079-6425. (Elsevier Ltd.)A review. The cosmetics industry was among the first to implement nanotechnol. principles in product development. Of more than one thousand registered nanotechnol.-based products on the global market in 2009, more than 13% were classified as products for cosmetic use. In this review we highlight the most important scientific articles, expert opinions by regulatory authorities, and patent literature from Europe and the USA for the time period between 2000 and 2010 concerning the use of nanotechnol. in dermatol., dental, and haircare products intended for improving the appearance of the user. We present current and suggested uses of nanotechnol. in cosmetics with the main focus on nanomaterials as active substances, carriers and formulation aids. The new functionalities these materials are claimed to introduce are also described. We briefly discuss public opinion of nanotechnol. in general, and include the most important definitions related to this emerging technol. along with a summary of the general characteristics of nanoparticles and their safety aspects. The aim of the review is, thus, to provide an update on the current status and trends of research and industrial development related to the use of nanotechnol. in cosmetics and to give an indication of where the field could be heading in the future.
- 11Morry, J.; Ngamcherdtrakul, W.; Gu, S. D.; Goodyear, S. M.; Castro, D. J.; Reda, M. M.; Sangvanich, T.; Yantasee, W. Dermal delivery of HSP47 siRNA with NOX4-modulating mesoporous silica-based nanoparticles for treating fibrosis Biomaterials 2015, 66, 41– 52 DOI: 10.1016/j.biomaterials.2015.07.00511Dermal delivery of HSP47 siRNA with NOX4-modulating mesoporous silica-based nanoparticles for treating fibrosisMorry, Jingga; Ngamcherdtrakul, Worapol; Gu, Shenda; Goodyear, Shaun M.; Castro, David J.; Reda, Moataz M.; Sangvanich, Thanapon; Yantasee, WassanaBiomaterials (2015), 66 (), 41-52CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)Fibrotic diseases such as scleroderma have been linked to increased oxidative stress and upregulation of pro-fibrotic genes. Recent work suggests a role of NADPH oxidase 4 (NOX4) and heat shock protein 47 (HSP47) in inducing excessive collagen synthesis, leading to fibrotic diseases. Herein, we elucidate the relationship between NOX4 and HSP47 in fibrogenesis and propose to modulate them altogether as a new strategy to treat fibrosis. We developed a nanoparticle platform consisting of polyethylenimine (PEI) and polyethylene glycol (PEG) coating on a 50-nm mesoporous silica nanoparticle (MSNP) core. The nanoparticles effectively delivered small interfering RNA (siRNA) targeting HSP47 (siHSP47) in an in vitro model of fibrosis based on TGF-β stimulated fibroblasts. The MSNP core also imparted an antioxidant property by scavenging reactive oxygen species (ROS) and subsequently reducing NOX4 levels in the in vitro fibrogenesis model. The nanoparticle was far superior to n-acetyl cysteine (NAC) at modulating pro-fibrotic markers. In vivo evaluation was performed in a bleomycin-induced scleroderma mouse model, which shares many similarities to human scleroderma disease. Intradermal administration of siHSP47-nanoparticles effectively reduced HSP47 protein expression in skin to normal level. In addn., the antioxidant MSNP also played a prominent role in reducing the pro-fibrotic markers, NOX4, alpha smooth muscle actin (α-SMA), and collagen type I (COL I), as well as skin thickness of the mice.
- 12Kilpeläinen, M.; Riikonen, J.; Vlasova, M. A.; Huotari, A.; Lehto, V. P.; Salonen, J.; Herzig, K. H.; Järvinen, K. In vivo delivery of a peptide, ghrelin antagonist, with mesoporous silicon microparticles J. Controlled Release 2009, 137, 166– 70 DOI: 10.1016/j.jconrel.2009.03.01712In vivo delivery of a peptide, ghrelin antagonist, with mesoporous silicon microparticlesKilpelainen M; Riikonen J; Vlasova M A; Huotari A; Lehto V P; Salonen J; Herzig K H; Jarvinen KJournal of controlled release : official journal of the Controlled Release Society (2009), 137 (2), 166-70 ISSN:.Peptides may represent potential treatment options for many severe illnesses. However, they need an effective delivery system to overcome rapid degradation after their administration. One possible way to prolong peptide action is to use particulate drug delivery systems. In the present study, thermally hydrocarbonized mesoporous silicon (THCPSi) microparticles (38-53 microm) were studied as a peptide delivery system in vivo. D-lys-GHRP6 (ghrelin antagonist, GhA) was used as a model peptide. The effects of GhA-loaded THCPSi microparticles on food intake (s.c., GhA dose 14 mg/kg) and on blood pressure (s.c., GhA dose 4 mg/kg) were examined in mice and rats, respectively. In addition, the effects of THCPSi microparticles (2 mg) on cytokine secretion in mice after single s.c. administration were examined by determining several cytokine plasma concentrations. The present results demonstrate that GhA can be loaded into THCPSi microparticles with a high loading degree (20% w/w). GhA loaded THCPSi microparticles inhibited food intake for a prolonged time, and increased blood pressure more slowly than encountered with a GhA solution. Furthermore, THCPSi microparticles did not increase cytokine activity. The present results suggest that THCPSi might be used as a drug delivery system for peptides.
- 13Canham, L. Porous Silicon for Oral Hygiene and Cosmetics. In Handbook of Porous Silicon; Canham, L., Ed.; Springer International Publishing: Cham, 2014; pp 1– 8.There is no corresponding record for this reference.
- 14Widenmeyer, M.; Anwander, R. Pore size control of highly ordered mesoporous silica MCM-48 Chem. Mater. 2002, 14, 1827– 1831 DOI: 10.1021/cm011273bThere is no corresponding record for this reference.
- 15Yamada, T.; Zhou, H. S.; Asai, K.; Honma, I. Pore size controlled mesoporous silicate powder prepared by triblock copolymer templates Mater. Lett. 2002, 56, 93– 96 DOI: 10.1016/S0167-577X(02)00424-X15Pore size controlled mesoporous silicate powder prepared by triblock copolymer templatesYamada, Takeo; Zhou, Haoshen; Asai, Keisuke; Honma, ItaruMaterials Letters (2002), 56 (1-2), 93-96CODEN: MLETDJ; ISSN:0167-577X. (Elsevier Science B.V.)The pore sizes of SBA-15 and SBA-16 were controlled well by the direct micelle control method, which was related with assembled conditions of the soln. temp. and concn. of the triblock copolymer. The relation between the pore size of the mesoporous silica and the assembled conditions is the same as that one among the core radius of the micelle triblock copolymer, the soln. temp. T, and the crit. micellization temp. Tc in ≈(T-Tc)0.2.
- 16Forsgren, J.; Frykstrand, S.; Grandfield, K.; Mihranyan, A.; Strømme, M. A Template-Free, Ultra-Adsorbing, High Surface Area Carbonate Nanostructure PLoS One 2013, 8e68486 DOI: 10.1371/journal.pone.006848616A template-free, ultra-adsorbing, high surface area carbonate nanostructureForsgren, Johan; Frykstrand, Sara; Grandfield, Kathryn; Mihranyan, Albert; Stroemme, MariaPLoS One (2013), 8 (7), e68486CODEN: POLNCL; ISSN:1932-6203. (Public Library of Science)We report the template-free, low-temp. synthesis of a stable, amorphous, and anhyd. magnesium carbonate nanostructure with pore sizes below 6 nm and a sp. surface area of ∼800 m2 g-1, substantially surpassing the surface area of all previously described alkali earth metal carbonates. The moisture sorption of the novel nanostructure is featured by a unique set of properties including an adsorption capacity ∼50% larger than that of the hygroscopic zeolite-Y at low relative humidities and with the ability to retain more than 75% of the adsorbed water when the humidity is decreased from 95% to 5% at room temp. These properties can be regenerated by heat treatment at temps. below 100°C. The structure is foreseen to become useful in applications such as humidity control, as industrial adsorbents and filters, in drug delivery and catalysis.
- 17Frykstrand, S.; Forsgren, J.; Mihranyan, A.; Strømme, M. On the pore forming mechanism of Upsalite, a micro- and mesoporous magnesium carbonate Microporous Mesoporous Mater. 2014, 190, 99– 104 DOI: 10.1016/j.micromeso.2013.12.011There is no corresponding record for this reference.
- 18Pochard, I.; Frykstrand, S.; Ahlström, O.; Forsgren, J.; Strømme, M. Water and ion transport in ultra-adsorbing porous magnesium carbonate studied by dielectric spectroscopy J. Appl. Phys. 2014, 115044306 DOI: 10.1063/1.4860276There is no corresponding record for this reference.
- 19Pochard, I.; Frykstrand, S.; Eriksson, J.; Gustafsson, S.; Welch, K.; Strømme, M. Dielectric Spectroscopy Study of Water Behavior in Calcined Upsalite: A Mesoporous Magnesium Carbonate without Organic Surface Groups J. Phys. Chem. C 2015, 119, 15680– 15688 DOI: 10.1021/acs.jpcc.5b02370There is no corresponding record for this reference.
- 20Zhang, P.; Forsgren, J.; Strømme, M. Stabilisation of amorphous ibuprofen in Upsalite, a mesoporous magnesium carbonate, as an approach to increasing the aqueous solubility of poorly soluble drugs Int. J. Pharm. 2014, 472, 185– 191 DOI: 10.1016/j.ijpharm.2014.06.02520Stabilisation of amorphous ibuprofen in Upsalite, a mesoporous magnesium carbonate, as an approach to increasing the aqueous solubility of poorly soluble drugsZhang, Peng; Forsgren, Johan; Stroemme, MariaInternational Journal of Pharmaceutics (Amsterdam, Netherlands) (2014), 472 (1-2), 185-191CODEN: IJPHDE; ISSN:0378-5173. (Elsevier B.V.)One attractive approach to increase the aq. soly. and thus the bioavailability of poorly sol. drugs is to formulate them in their amorphous state since amorphous compds. generally exhibit higher apparent solubilities than their cryst. counterparts. In the current work, mesoporous magnesium carbonate was used to stabilize the amorphous state of the model substance ibuprofen. Crystn. of the drug was completely suppressed in the formulation, resulting in both a higher apparent soly. and a three times faster dissoln. rate of the drug where the drug release was shown to be diffusion controlled. It was also shown that the formulation is stable for at least three months when stored at 75% relative humidity. The simple synthesis together with a high loading capacity and narrow pore size distribution of the mesoporous magnesium carbonate is foreseen to offer great advantages in formulations of poorly sol. drugs.
- 21Zhang, P.; Zardán Goméz De La Torre, T.; Forsgren, J.; Bergström, C. A. S.; Strømme, M. Diffusion-Controlled Drug Release from the Mesoporous Magnesium Carbonate Upsalite J. Pharm. Sci. 2016, 105, 657– 663 DOI: 10.1002/jps.2455321Diffusion-Controlled Drug Release from the Mesoporous Magnesium Carbonate UpsaliteZhang, Peng; Gomez De La Torre, Teresa Zardan; Forsgren, Johan; Bergstroem, Christel; Stromme, MariaJournal of Pharmaceutical Sciences (2016), 105 (2), 657-663CODEN: JPMSAE; ISSN:0022-3549. (Elsevier Inc.)In vitro drug release from well-defined particle-size fractions of the mesoporous magnesium carbonate material Upsalite was investigated in detail using ibuprofen, a biopharmaceutics classification system class II drug, as the model compd. The wt. of loaded drug corresponded to 30% of the wt. of the carrier and the pores were filled to approx. 80%. The incorporated ibuprofen was found to be in an amorphous state and was physisorbed, rather than chemisorbed, to the surfaces of the pore walls. In contrast to ibuprofen in mesoporous silica, there was no detectable drug on the outer surface of the carrier particles. Two ibuprofen doses were loaded into Upsalite particles with size fractions ranging from 25 μm to more than 200 μm. The initial release rate was controlled by the particle size; the dissoln. rate of the loaded ibuprofen during this period was more than four times faster than that of the cryst. drug. An extended-release period of about 24 h followed the initial rapid-release period. The features of this extended-release period were dependent on the total drug concn. in the release medium. Detailed anal. of the diffusion of ibuprofen in Upsalite provided the ibuprofen diffusion coeff. (9.8 × 10-8 cm2/s), the constrictivity of the diffusion process (0.47) and the tortuosity of the carrier (15). This relatively high tortuosity value indicates that Upsalite can be used not only to enhance the dissoln. rate of poorly sol. drugs but also as a carrier in sustained-release applications by using larger particle sizes or even pellets of the material. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Assocn. J Pharm Sci.
- 22Frykstrand, S.; Forsgren, J.; Zhang, P.; Strømme, M.; Ferraz, N. Cytotoxicity, in Vivo Skin Irritation and Acute Systemic Toxicity of the Mesoporous Magnesium Carbonate Upsalite J. Biomater. Nanobiotechnol. 2015, 6, 257– 266 DOI: 10.4236/jbnb.2015.64024There is no corresponding record for this reference.
- 23Høiby, N.; Jarlov, J. O.; Kemp, M.; Tvede, M.; Bangsborg, J. M.; Kjerulf, A.; Pers, C.; Hansen, H. Excretion of ciprofloxacin in sweat and multiresistant Staphylococcus epidermidis Lancet 1997, 349, 167– 9 DOI: 10.1016/S0140-6736(96)09229-XThere is no corresponding record for this reference.
- 24Bek-Thomsen, M.; Lomholt, H. B.; Kilian, M. Acne is not associated with yet-uncultured bacteria J. Clin. Microbiol. 2008, 46, 3355– 60 DOI: 10.1128/JCM.00799-0824Acne is not associated with yet-uncultured bacteriaBek-Thomsen, M.; Lomholt, H. B.; Kilian, M.Journal of Clinical Microbiology (2008), 46 (10), 3355-3360CODEN: JCMIDW; ISSN:0095-1137. (American Society for Microbiology)Current clin. and microbiol. information on acne fails to demonstrate a clear assocn. between particular species, including Propionibacterium acnes, and disease, and the disease continues to be a considerable problem. To test if acne is assocd. with hitherto uncultured bacteria residing in diseased skin follicles, sequencing and phylogenetic anal. of approx. 5,700 amplified and cloned 16S rRNA genes were used to det. the microbial diversity in follicles from acne patients and healthy individuals and from the superficial skin of acne patients. Follicles from healthy skin were exclusively colonized by P. acnes, whereas the follicular microbiota of acne patients included, in addn., Staphylococcus epidermidis and minor proportions of other species. In comparison, samples from superficial skin showed a complex microbiota represented by 12 to 16 bacterial species. The findings of the study exclude the possibility that acne is assocd. with yet-uncultured bacteria and shows that healthy skin follicles constitute a remarkably exclusive habitat allowing colonization only by P. acnes.
- 25Makhluf, S.; Dror, R.; Nitzan, Y.; Abramovich, Y.; Jelinek, R.; Gedanken, A. Microwave-assisted synthesis of nanocrystalline MgO and its use as a bacteriocide Adv. Funct. Mater. 2005, 15, 1708– 1715 DOI: 10.1002/adfm.20050002925Microwave-assisted synthesis of nanocrystalline MgO and its use as a bactericideMakhluf, Shirly; Dror, Rachel; Nitzan, Yeshayahu; Abramovich, Yaniv; Jelinek, Raz; Gedanken, AharonAdvanced Functional Materials (2005), 15 (10), 1708-1715CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)Nanocryst. particles of MgO were synthesized using microwave radiation in an ethylene glycol soln. The antibacterial activities of the MgO nanoparticles were tested by treating Escherichia coli (Gram neg.) and Staphylococcus aureus (Gram pos.) cultures with 1 mg mL-1 of the nanoparticles. The authors have examd. the importance of the size effect, pH, and the form of the active MgO species as a bactericidal agent. A clear size dependence of the nanoparticles is obsd. where the amt. of eradicated bacteria was strongly dependent on the particle size.
- 26Pan, X.; Wang, Y.; Chen, Z.; Pan, D.; Cheng, Y.; Liu, Z.; Lin, Z.; Guan, X. Investigation of Antibacterial Activity and Related Mechanism of a Series of Nano-Mg(OH)2 ACS Appl. Mater. Interfaces 2013, 5, 1137– 1142 DOI: 10.1021/am302910q26Investigation of antibacterial activity and related mechanism of a series of nano-Mg(OH)2Pan, Xiaohong; Wang, Yonghao; Chen, Zhi; Pan, Danmei; Cheng, Yangjian; Liu, Zunjing; Lin, Zhang; Guan, XiongACS Applied Materials & Interfaces (2013), 5 (3), 1137-1142CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)The authors report the antibacterial effect and related mechanism of three nano-Mg(OH)2 slurries using Escherichia coli as model bacteria. X-ray diffraction (XRD), SEM and laser particle size anal. revealed that the as-synthesized Mg(OH)2_MgCl2, Mg(OH)2_MgSO4 and Mg(OH)2_MgO are all composed by nanoflakes with different sizes, and their aggregates in water are 5.5, 4.5, and 1.2 μm, resp. Bactericidal tests showed that the antibacterial efficiency is conversely correlated with the size of Mg(OH)2 aggregates. Transmission electron microscopy (TEM) observation have not provided evidence of cellular internalization, however, the antibacterial effect is pos. correlation to the loss of integrity of cell walls. SEM and zeta potential anal. revealed that the adhering ability of Mg(OH)2 on the bacterial surface is Mg(OH)2_MgCl2 > Mg(OH)2_MgSO4 > Mg(OH)2_MgO, indicating the toxicity of Mg(OH)2 may be caused by the electrostatic interaction-induced external adsorption. Confocal laser scanning microscopy (CLSM) further revealed that the adhering of Mg(OH)2 on the bacterial surface could increase the permeability of cell membranes. Thus, the antibacterial mechanism of nano-Mg(OH)2 could be as follows: nano-Mg(OH)2 adsorbed on the bacterial surface by charge attraction first, and then destroying the integrity of cell walls, resulting in the final death of bacteria.
- 27Stoimenov, P. K.; Klinger, R. L.; Marchin, G. L.; Klabunde, K. J. Metal oxide nanoparticles as bactericidal agents Langmuir 2002, 18, 6679– 6686 DOI: 10.1021/la020237427Metal Oxide Nanoparticles as Bactericidal AgentsStoimenov, Peter K.; Klinger, Rosalyn L.; Marchin, George L.; Klabunde, Kenneth J.Langmuir (2002), 18 (17), 6679-6686CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Reactive magnesium oxide nanoparticles and halogen (Cl2, Br2) adducts of these MgO particles were allowed to contact certain bacteria and spore cells. Bacteriol. test data, at. force microscopy (AFM) images, and electron microscopy (TEM) images are provided, which yield insight into the biocidal action of these nanoscale materials. The tests show that these materials are very effective against Gram-pos. and Gram-neg. bacteria as well as spores. ζ-Potential measurements show an attractive interaction between the MgO nanoparticles and bacteria and spore cells, which is confirmed by confocal microscopy images. The AFM studies illustrate considerable changes in the cell membranes upon treatment, resulting in the death of the cells. TEM micrographs confirm these results and supply addnl. information about the processes inside the cells. Overall, the results presented illustrate that dry powder nanoparticulate formulations as well as water slurries are effective. It is proposed that abrasiveness, basic character, electrostatic attraction, and oxidizing power (due to the presence of active halogen) combine to promote these biocidal properties.
- 28Sawai, J.; Kojima, H.; Igarashi, H.; Hashimoto, A.; Shoji, S.; Takehara, A.; Sawaki, T.; Kokugan, T.; Shimizu, M. Escherichia coli damage by ceramic powder slurries J. Chem. Eng. Jpn. 1997, 30, 1034– 1039 DOI: 10.1252/jcej.30.103428Escherichia coli damage by ceramic powder slurriesSawai, Jun; Kojima, Hiromitsu; Igarashi, Hideo; Hashimoto, Atsushi; Shoji, Shinorbu; Takehara, Akemi; Sawaki, Takashi; Kokugan, Takao; Shimizu, MasaruJournal of Chemical Engineering of Japan (1997), 30 (6), 1034-1039CODEN: JCEJAQ; ISSN:0021-9592. (Society of Chemical Engineers, Japan)To elucidate the antibacterial mechanisms of the ceramics magnesium oxide (MgO), calcium oxide (CaO) and zinc oxide (ZnO), damage to bacteria caused by these powder slurries are studied on the basis of change in sensitivities to antibiotics, of which the primary inhibitory actions are understood well. Four kinds of antibiotics, penicillin G, chloramphenicol, nalidixic acid and rifampicin, were used as the selective reagents. The MgO and CaO powder slurries increased the sensitivities of Escherichia coli to rifampicin and chloramphenicol. Though the MgO and CaO powder slurries have high pH values, changes in the sensitivities by the MgO and CaO powder slurries were obviously different from those via alk. treatment. The ZnO powder slurry enhanced the sensitivity of the E. coli to chloramphenicol. This result suggests that the antibacterial actions of MgO and CaO powder slurries were different from those of ZnO powder slurry.
- 29Yamamoto, O.; Sawai, J.; Sasamoto, T. Change in antibacterial characteristics with doping amount of ZnO in MgO-ZnO solid solution Int. J. Inorg. Mater. 2000, 2, 451– 454 DOI: 10.1016/S1466-6049(00)00045-329Change in antibacterial characteristics with doping amount of ZnO in MgO-ZnO solid solutionYamamoto, Osamu; Sawai, Jun; Sasamoto, TadashiInternational Journal of Inorganic Materials (2000), 2 (5), 451-454CODEN: IJIMCR; ISSN:1466-6049. (Elsevier Science Ltd.)Antibacterial activity for MgO-ZnO solid soln. was studied by measuring the change in elec. cond. with bacterial growth. MgO-ZnO solid soln. powders were prepd. by heating at 1400°C for 3 h in air. A single phase with cubic type structure was obtained in the wt. ratio range (MgO/ZnO) of 4.0 and 1.5, but the ratio of 0.67 resulted in a ZnO phase in addn. to solid soln. After milling the solid soln. powders by planetary ball mill, the av. particle size and the sp. surface area of these powders became 0.1 μm and 26 m2/g, resp., which were used in the test of antibacterial activity. From the results of antibacterial tests, the activity increased with increasing the powder concn. in the medium. With increasing the doping amt. of ZnO in MgO-ZnO solid soln., it was found to show a decrease in the antibacterial activity against Escherichia coli and Staphylococcus aureus. The pH value in physiol. saline at the powder concn. of 2.5 mg/mL showed the alkali region above 10.0, and decreased with the increase of ZnO amt. in solid soln. The decrease in antibacterial activity, therefore, was assocd. with the decrease of pH value in medium.
- 30Hewitt, C. J.; Bellara, S. R.; Andreani, A.; Nebe-Von-Caron, G.; McFarlane, C. M. An evaluation of the anti-bacterial action of ceramic powder slurries using multi-parameter flow cytometry Biotechnol. Lett. 2001, 23, 667– 675 DOI: 10.1023/A:101037971467330An evaluation of the antibacterial action of ceramic powder slurries using multi-parameter flow cytometryHewitt, Christopher J.; Bellara, Sanjay R.; Andreani, Andrea; Nebe-Von-Caron, Gerhard; McFarlane, Caroline M.Biotechnology Letters (2001), 23 (9), 667-675CODEN: BILED3; ISSN:0141-5492. (Kluwer Academic Publishers)Multi-parameter flow cytometric techniques have been used to study the effects of three ceramic powders CaO, MgO and ZnO on the physiol. of individual, exponentially growing E. coli cells. While all three powders inhibited reproductive growth, depending on their concn., the mechanism of action of CaO and MgO was different to that of ZnO as shown by fluorescent staining techniques developed in our lab.
- 31Huang, L.; Li, D.; Lin, Y.; Evans, D. G.; Duan, X. Influence of nano-MgO particle size on bactericidal action against Bacillus subtilis var. niger Chin. Sci. Bull. 2005, 50, 514– 519 DOI: 10.1007/BF0289747431Influence of nano-MgO particle size on bactericidal action against Bacillus subtilis var. nigerHuang, Lei; Li, Dianqing; Lin, Yanjun; Evans, David G.; Duan, XueChinese Science Bulletin (2005), 50 (6), 514-519CODEN: CSBUEF; ISSN:1001-6538. (Science in China Press)Nano-MgO with various particle sizes, synthesized by different methods using Mg(NO3)2·6H2O, Na2CO3, Na2SO4, urea and ammonia soln. as reactants, was used to carry out bactericidal expts. on Bacillus subtilis var. niger. The results were compared with the effect of TiO2, a common kind of photocatalytic material. The materials were characterized by X-ray diffraction, transmission electron microscopy, low temp. N2 adsorption-desorption measurements and FT-IR, and the results showed that the bactericidal ability of MgO increases with decreasing particle size. Nano-MgO and an interior wall-paint contg. the material have better bactericidal effects than nano-TiO2 in both presence and absence of light. The bactericidal mechanism is discussed. The surface of MgO can generate high concns. of O2- which is highly active and can react with the peptide linkages in the coating walls of the spores. The spores are destroyed by the resulting damage to their structure.
- 32Huang, L.; Li, D. Q.; Lin, Y. J.; Wei, M.; Evans, D. G.; Duan, X. Controllable preparation of Nano-MgO and investigation of its bactericidal properties J. Inorg. Biochem. 2005, 99, 986– 993 DOI: 10.1016/j.jinorgbio.2004.12.02232Controllable preparation of Nano-MgO and investigation of its bactericidal propertiesHuang, Lei; Li, Dian-Qing; Lin, Yan-Jun; Wei, Min; Evans, David G.; Duan, XueJournal of Inorganic Biochemistry (2005), 99 (5), 986-993CODEN: JIBIDJ; ISSN:0162-0134. (Elsevier B.V.)Samples of nano-MgO with varying particle sizes were prepd. by four different methods using Mg(NO3)2·6H2O, Na2CO3, urea and NH3 as raw materials and characterized by XRD, TEM, low temp. N2 adsorption-desorption measurements and FTIR spectroscopy. Bactericidal expts. with Bacillus subtilis var. niger and Staphylococcus aureus were carried out using as-synthesized nano-MgO samples and the bactericidal mechanism was also studied. The bactericidal efficacy of nano-MgO increases with decreasing particle size. The bactericidal efficacy of the samples was compared with that of TiO2, a common photoactive bactericidal material. The nano-MgO has better bactericidal activity, both when used directly and as an additive in an interior wall paint. Also, nano-MgO is active even in the absence of irradn.
- 33Krishnamoorthy, K.; Manivannan, G.; Kim, S. J.; Jeyasubramanian, K.; Premanathan, M. Antibacterial activity of MgO nanoparticles based on lipid peroxidation by oxygen vacancy J. Nanopart. Res. 2012, 141063 DOI: 10.1007/s11051-012-1063-633Antibacterial activity of MgO nanoparticles based on lipid peroxidation by oxygen vacancyKrishnamoorthy, Karthikeyan; Manivannan, Govindasamy; Kim, Sang Jae; Jeyasubramanian, Kadarkaraithangam; Premanathan, MariappanJournal of Nanoparticle Research (2012), 14 (9), 1063/1-1063/10CODEN: JNARFA; ISSN:1388-0764. (Springer)Antibacterial activity of MgO nanoparticles (NPs) was evaluated against the Gram-neg. bacteria Escherichia coli and Pseudomonas aeruginosa as well as the Gram-pos. bacterium Staphylococcus aureus by microtitre plate-based assay incorporating resazurin as an indicator of cell growth. MgO NPs exhibited antibacterial activity with minimal inhibitory concn. of 500 μg/mL against E. coli and 1,000 μg/mL for P. aeruginosa and S. aureus. MgO NPs enhanced ultrasound-induced lipid peroxidn. in the liposomal membrane. The mechanism of the antibacterial activity of the MgO NPs relied on the presence of defects or oxygen vacancy at the surface of the nanoparticle which led to the lipid peroxidn. and reactive oxygen species generation.
- 34Yamamoto, O.; Fukuda, T.; Kimata, M.; Sawai, J.; Sasamoto, T. Antibacterial characteristics of MgO-mounted spherical carbons prepared by carbonization of ion-exchanged resin J. Ceram. Soc. Jpn. 2001, 109, 363– 365 DOI: 10.2109/jcersj.109.1268_36334Antibacterial characteristics of MgO-mounted spherical carbons prepared by carbonization of ion-exchanged resinYamamoto, Osamu; Fukuda, Taiki; Kimata, Mitsumasa; Sawai, Jun; Sasamoto, TadashiJournal of the Ceramic Society of Japan (2001), 109 (April), 363-365CODEN: JCSJEW; ISSN:0914-5400. (Ceramic Society of Japan)Ion-exchange resins with particle size of 0.5 mm were treated by an aq. soln. of MgSO4 and then they were carbonized for 1 h in nitrogen gas at 300-1000°C. The amt. of MgO in the carbon samples was ∼30 wt.%, irresp. of carbonization temp. The antibacterial activity of carbon samples contg. MgO was examd. by the colony count method. The pH values in physiol. saline dispersed within carbon samples were in the range of 9.4-9.8, but the values did not affect the occurrence of antibacterial activity. From the antibacterial tests, it was found that the antibacterial activity for Escherichia coli and Staphylococcus aureus on carbon samples contg. MgO increased with increasing carbonization temp. of the ion-exchanged resin.
- 35Yamamoto, O.; Ohira, T.; Alvarez, K.; Fukuda, M. Antibacterial characteristics of CaCO3-MgO composites Mater. Sci. Eng. B 2010, 173, 208– 212 DOI: 10.1016/j.mseb.2009.12.00735Antibacterial characteristics of CaCO3-MgO compositesYamamoto, Osamu; Ohira, Toshiaki; Alvarez, Kelly; Fukuda, MasayukiMaterials Science & Engineering, B: Advanced Functional Solid-State Materials (2010), 173 (1-3), 208-212CODEN: MSBTEK; ISSN:0921-5107. (Elsevier B.V.)Dentifrices, such as tooth-paste, are pastes contg. insol. abrasives that aid in the removal of plaque from the teeth and help to polish them. Composite powders contributing to oral hygiene application, i.e., nano-scale MgO crystallite dispersed in CaCO3 grain, were fabricated by the thermal decompn. of dolomite. The composite obtained by heating at 800 °C consisted of CaCO3 grains including 20 nm MgO fine crystallite, being the purpose powder in this study. The antibacterial activity of these powders related to gram-pos. and gram-neg. bacteria was evaluated in vitro. The thermal decompn. above 800 °C resulted in the mixt. of CaO and MgO. Antibacterial activity of the composite enhanced with increasing powder concn. Though antibacterial action toward Staphylococcus aureus was greater than towards Escherichia coli, the death rate const. was identical in both bacteria. It can be concluded that the obtained composite possesses two functions able to improve the oral hygiene: as a tooth abrasive and as an antibacterial agent.
- 36Sawai, J.; Kojima, H.; Igarashi, H.; Hashimoto, A.; Shoji, S.; Sawaki, T.; Hakoda, A.; Kawada, E.; Kokugan, T.; Shimizu, M. Antibacterial characteristics of magnesium oxide powder World J. Microbiol. Biotechnol. 2000, 16, 187– 194 DOI: 10.1023/A:100891620978436Antibacterial characteristics of magnesium oxide powderSawai, J.; Kojima, H.; Igarashi, H.; Hashimoto, A.; Shoji, S.; Sawaki, T.; Hakoda, A.; Kawada, E.; Kokugan, T.; Shimizu, M.World Journal of Microbiology & Biotechnology (2000), 16 (2), 187-194CODEN: WJMBEY; ISSN:0959-3993. (Kluwer Academic Publishers)The antibacterial activity of magnesium oxide (MgO) was studied. Inhibitory zones appeared around the MgO powder slurry put directly on nutrient agar plates seeded with Escherichia coli or Staphylococcus aureus. However, no zone was obsd. using a penicillin cup to avoid contact between the bacteria and the MgO powder. Moreover, the supernatant soln. of the MgO powder slurry and a MgCl2 soln. contg. Mg2+ at a concn. of the soly. of MgO did not affect the growth of E. coli and S. aureus. Moreover, elevated shaking speed increased the death of E. coli in the slurry, indicating that the contact frequency between bacterial cells and MgO powders affected the antibacterial activity. It was considered that the contact between MgO powder and bacteria was important for the occurrence of its antibacterial activity. Since the generation of active oxygen, such as O2, from the MgO powder slurry was detected by chemiluminescence anal., an investigation was carried out to det. whether active oxygen generated from MgO powder slurry was related to its antibacterial activity. The changes in the antibiotic sensitivity in E. coli treated by MgO powder agreed with those by active oxygen treatment. These results suggested that the active oxygen generated from the MgO powder slurry was one of the primary factors in its antibacterial activity.
- 37Sawai, J.; Shiga, H.; Kojima, H. Kinetic analysis of death of bacteria in CaO powder slurry Int. Biodeterior. Biodegrad. 2001, 47, 23– 26 DOI: 10.1016/S0964-8305(00)00115-337Kinetic analysis of death of bacteria in CaO powder slurrySawai, J.; Shiga, H.; Kojima, H.International Biodeterioration & Biodegradation (2001), 47 (1), 23-26CODEN: IBBIES; ISSN:0964-8305. (Elsevier Science Ltd.)The process of Escherichia coli and Staphylococcus aureus death in CaO powder slurry was assumed to follow 1st-order reaction kinetics. The apparent death rate const. (k) increased with increasing powder concn. and was higher than that for a NaOH soln. having the same pH as the CaO powder slurry. The slurry temp. significantly affected the bactericidal action of the CaO powder slurry against both E. coli and S. aureus. The slope of the Arrhenius plot of k for both bacteria changed at a slurry temp. of ∼22°, suggested to correspond to a change in the activation energy required to induce the death of bacteria in CaO powder slurry as a result of a phase transition of the cell membrane.
- 38Rawlinson, L. A.; O’Gara, J. P.; Jones, D. S.; Brayden, D. J. Resistance of Staphylococcus aureus to the cationic antimicrobial agent poly(2-(dimethylamino ethyl)methacrylate) (pDMAEMA) is influenced by cell-surface charge and hydrophobicity J. Med. Microbiol. 2011, 60, 968– 76 DOI: 10.1099/jmm.0.025619-038Resistance of Staphylococcus aureus to the cationic antimicrobial agent poly(2-(dimethylamino ethyl)methacrylate) (pDMAEMA) is influenced by cell-surface charge and hydrophobicityRawlinson Lee-Anne B; O'Gara James P; Jones David S; Brayden David JJournal of medical microbiology (2011), 60 (Pt 7), 968-76 ISSN:.Cationic antimicrobial agents may prevent device-associated infections caused by Staphylococcus epidermidis and Staphylococcus aureus. This study reports that the cationic antimicrobial polymer poly(2-(dimethylamino ethyl)methacrylate) (pDMAEMA) was more effective at antagonizing growth of clinical isolates of S. epidermidis than of S. aureus. Importantly, mature S. epidermidis biofilms were significantly inactivated by pDMAEMA. The S. aureus isolates tested were generally more hydrophobic than the S. epidermidis isolates and had a less negative charge, although a number of individual S. aureus and S. epidermidis clinical isolates had similar surface hydrophobicity and charge values. Fluorescence spectroscopy and flow cytometry revealed that fluorescently labelled pDMAEMA interacted strongly with S. epidermidis compared with S. aureus. S. aureus ΔdltA and ΔmprF mutants were less hydrophobic and therefore more susceptible to pDMAEMA than wild-type S. aureus. Although the different susceptibility of S. epidermidis and S. aureus isolates to pDMAEMA is complex, influenced in part by surface hydrophobicity and charge, these findings nevertheless reveal the potential of pDMAEMA to treat S. epidermidis infections.
- 39Carter, C. B.; Norton, M. G. Coatings and Thick Films. In Ceramic Materials: Science and Engineering, 2nd ed.; Springer Science+Business Media: New York, 2013; p 502.There is no corresponding record for this reference.
- 40Gence, N.; Ozbay, N. pH dependence of electrokinetic behavior of dolomite and magnesite in aqueous electrolyte solutions Appl. Surf. Sci. 2006, 252, 8057– 8061 DOI: 10.1016/j.apsusc.2005.10.015There is no corresponding record for this reference.
- 41Vinu, A.; Murugesan, V.; Hartmann, M. Adsorption of lysozyme over mesoporous molecular sieves MCM-41 and SBA-15: Influence of pH and aluminum incorporation J. Phys. Chem. B 2004, 108, 7323– 7330 DOI: 10.1021/jp037303aThere is no corresponding record for this reference.
- 42Unosson, E.; Morgenstern, M.; Engqvist, H.; Welch, K. In vitro antibacterial properties and UV induced response from Staphylococcus epidermidis on Ag/Ti oxide thin films J. Mater. Sci.: Mater. Med. 2016, 27, 49 DOI: 10.1007/s10856-015-5662-542In vitro antibacterial properties and UV induced response from Staphylococcus epidermidis on Ag/Ti oxide thin filmsUnosson Erik; Morgenstern Matthias; Engqvist Hakan; Welch KenJournal of materials science. Materials in medicine (2016), 27 (3), 49 ISSN:.Implanted materials are susceptible to bacterial colonization and biofilm formation, which can result in severe infection and lost implant function. UV induced photocatalytic disinfection on TiO2 and release of Ag(+) ions are two promising strategies to combat such events, and can be combined for improved efficiency. In the current study, a combinatorial physical vapor deposition technique was utilized to construct a gradient coating between Ag and Ti oxide, and the coating was evaluated for antibacterial properties in darkness and under UV light against Staphylococcus epidermidis. The findings revealed a potent antibacterial effect in darkness due to Ag(+) release, with near full elimination (97%) of viable bacteria and visible cell lysis on Ag dominated surfaces. The photocatalytic activity, however, was demonstrated poor due to low TiO2 crystallinity, and UV light irradiation of the coating did not contribute to the antibacterial effect. On the contrary, bacterial viability was in several instances higher after UV illumination, proposing a UV induced SOS response from the bacteria that limited the reduction rate during Ag(+) exposure. Such secondary effects should thus be considered in the development of multifunctional coatings that rely on UV activation.
- 43Heikkilä, T.; Santos, H. A.; Kumar, N.; Murzin, D. Y.; Salonen, J.; Laaksonen, T.; Peltonen, L.; Hirvonen, J.; Lehto, V. P. Cytotoxicity study of ordered mesoporous silica MCM-41 and SBA-15 microparticles on Caco-2 cells Eur. J. Pharm. Biopharm. 2010, 74, 483– 494 DOI: 10.1016/j.ejpb.2009.12.00643Cytotoxicity study of ordered mesoporous silica MCM-41 and SBA-15 microparticles on Caco-2 cellsHeikkila Teemu; Santos Helder A; Kumar Narendra; Murzin Dmitry Yu; Salonen Jarno; Laaksonen Timo; Peltonen Leena; Hirvonen Jouni; Lehto Vesa-PekkaEuropean journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V (2010), 74 (3), 483-94 ISSN:.Cytotoxicity of ordered mesoporous silica MCM-41 and SBA-15 microparticles (fractions between 1 and 160 microm) was determined in vitro on undifferentiated human colon carcinoma (Caco-2) cell line, considering the feasibility of using these silica-based materials in oral drug formulations. The cellular endpoints employed for assessing the effects of the MCM-41 and SBA-15 microparticles on Caco-2 were: (1) cell membrane integrity by monitoring live-cell protease activity (AFC) and by employing the flow cytometry method; (2) metabolic activity by monitoring total ATP content via luminescence assay; (3) activity of apoptotic effectors by caspase-3/7 activity assay. The generation of reactive oxygen species (ROS) was also followed, specifically the hydrogen peroxide (H(2)O(2)) and the superoxide radical (O(2)(-)). MCM-41 and SBA-15 microparticles caused cytotoxic effects on the Caco-2 cells, at most tested concentrations (0.2-14 mg/ml) and incubation times (3 and 24h). The effects on the cells included weakened cell membrane integrity, diminished cell metabolism and increased apoptotic signalling. The root cause for the cytotoxicity was heightened production of reactive oxygen species (ROS), especially the formation of the superoxide radical O(2)(-) already after 3h incubation with threshold dose 1mg/ml, apparently overwhelming the antioxidant defences and causing mitochondrial dysfunction, hence increasing the apoptotic signalling.
- 44WHO. Essential Medicines and Health Products, Methods of Sterilization. In The International Pharmacopoeia, 5th ed. [Online]; WHO, 2015. http://apps.who.int/phint/alt/index.html#d/b.7.5.9 (accessed Sept 1, 2016).There is no corresponding record for this reference.
- 45Sarker, S. D.; Nahar, L.; Kumarasamy, Y. Microtitre plate-based antibacterial assay incorporating resazurin as an indicator of cell growth, and its application in the in vitro antibacterial screening of phytochemicals Methods 2007, 42, 321– 4 DOI: 10.1016/j.ymeth.2007.01.00645Microtitre plate-based antibacterial assay incorporating resazurin as an indicator of cell growth, and its application in the in vitro antibacterial screening of phytochemicalsSarker, Satyajit D.; Nahar, Lutfun; Kumarasamy, YashodharanMethods (Oxford, United Kingdom) (2007), 42 (4), 321-324CODEN: MTHDE9; ISSN:1046-2023. (Elsevier Ltd.)The resazurin assay utilizing microtitre-plate, described by Drummond and Waigh in 2000, has been modified to achieve more accuracy in the detn. of the min. inhibitory concn. (MIC) values of natural products, including crude exts., chromatog. fractions or purified compds. against various bacterial strains. This modified resazurin method is simple, sensitive, rapid, robust and reliable, and could be used successfully to assess antibacterial properties of natural products.