Direct assembly of hydrophobic nanoparticles to multifunction structures

Abstract

A process that allows convenient production of multifunctional composite particles by direct self-assembly of hydrophobic nanoparticles on host nanostructures containing high density surface thiol groups is present. Hydrophobic nanoparticles of various compositions and combinations can be directly assembled onto the host surface through the strong coordination interactions between metal cations and thiol groups. The resulting structures can be further conveniently overcoated with a layer of normal silica to stabilize the assemblies and render them highly dispersible in water for biomedical applications. As the entire fabrication process does not involve complicated surface modification procedures, the hydrophobic ligands on the nanoparticles are not disturbed significantly so that they retain their original properties such as highly efficient luminescence. Multifunctional nonspherical nanostructures can be produced by using mercapto-silica coated nano-objects of arbitrary shapes as hosts for immobilizing functional nanoparticles. Multilayer structures can be achieved by repeating the mercapto-silica coating and nanoparticle immobilization processes.