title: Directed self-assembly of functionalized silica nanoparticles on molecular printboards through multivalent supramolecular interactions.
abstract: Silica nanoparticles functionalized with beta-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.
authors.affiliation: Laboratory for Supramolecular Chemistry and Technology, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Venkataramanan
authors.initials: V
authors.lastname: Mahalingam
authors.forename: Steffen
authors.initials: S
authors.lastname: Onclin
authors.forename: Mária
authors.initials: M
authors.lastname: Péter
authors.forename: Bart Jan
authors.initials: BJ
authors.lastname: Ravoo
authors.forename: Jurriaan
authors.initials: J
authors.lastname: Huskens
authors.forename: David N
authors.initials: DN
authors.lastname: Reinhoudt
mesh_terms: D005944:Glucosamine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D012822:Silicon Dioxide / Q000737:chemistry*; D047392:beta-Cyclodextrins / Q000737:chemistry
chemical_list: D047392:beta-Cyclodextrins; D012822:Silicon Dioxide; D005944:Glucosamine