Directed Self-Assembly of Functionalized Silica Nanoparticles on Molecular Printboards through Multivalent Supramolecular Interactions

Venkataramanan Mahalingam,† Steffen Onclin, Mária Péter, Bart Jan Ravoo, Jurriaan Huskens,* and David N. Reinhoudt*
Laboratory for Supramolecular Chemistry and Technology, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
Langmuir, 2004, 20 (26), pp 11756–11762
DOI: 10.1021/la047982w
Publication Date (Web): November 12, 2004
Copyright © 2004 American Chemical Society
†

 Present address:  University of Victoria, Canada.

,
*

 Authors to whom correspondence should be addressed. E-mail:  j.huskens@utwente.nl; E-mail: d.n.reinhoudt@utwente.nl.

Abstract

Abstract Image

Silica nanoparticles functionalized with β-cyclodextrin (CD) host molecules (5) have been prepared by reacting carboxylic active ester-terminated silica nanoparticles (4) with CD heptamine. Silica nanoparticles functionalized with glucosamine (6), having similar surface properties as 5 but lacking the host−guest recognition motif, were used to perform blank experiments. The CD-functionalized silica nanoparticles 5 were determined by TEM to be 55 ± 6 nm in size. They exhibited pH-dependent aggregation, which is explained by the presence of free amino and carboxylic acid groups on the particle surface, which was corroborated by zeta potential measurements. The functionalization with CD was further confirmed by host−guest studies in solution and at CD-functionalized silicon substrates. The addition of an adamantyl-terminated dendrimer, capable of multivalent host−guest binding with CD, led to strong aggregation of the CD particles 5, but not of the glucosamine-functionalized 6. Furthermore, 5 gave strong adsorption to CD monolayers on silicon onto which adamantyl-terminated dendrimers were adsorbed, whereas 6 did not. The good discrimination between dendrimer-covered and uncovered areas of the CD monolayer substrates allowed the directed self-assembly of the silica particles 5 onto dendrimer-patterned areas created by microcontact printing.

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History

  • Published In Issue December 21, 2004
  • Received August 12, 2004
    Revised September 22, 2004

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