Immobilizing Au Nanoparticles on SiO₂ Surfaces Using Octadecylsiloxane Monolayers

Gold nanoparticles were immobilized on silicon dioxide (SiO 2 ) surfaces by embedding them in a layer of octadecylsiloxane (ODS) and also in SiO 2 layers created by deposition and oxidation of ODS layers. The ODS and the SiO 2 layers form selectively around the nanoparticles. Analysis of the particles after several deposition/oxidation cycles showed a decrease in measured height in accordance with the number of deposited layers. Following one embedding cycle, the nanoparticles could not be moved with the tip of a scanning force microscope operated in dynamic mode, whereas they moved in a controlled fashion prior to the deposition of any layer. Depositing a second set of particles onto an ODS layer in contact with the substrate allowed us to construct a two-particle column by placing one particle directly on top of another one.