Immobilizing Au nanoparticles on SiO2 surfaces using octadecylsiloxane monolayers

Gold nanoparticles were immobilized on silicon dioxide (SiO2) surfaces by e mbedding them in a layer of octadecylsiloxane (ODS) and also in SiO2 layers created by deposition and oxidation of ODS layers. The ODS and the SiO2 la yers form selectively around the nanoparticles. Analysis of the particles a fter several deposition/oxidation cycles showed a decrease in measured heig ht in accordance with the number of deposited layers. Following one embeddi ng cycle, the nanoparticles could not be moved with the tip of a scanning f orce microscope operated in dynamic mode, whereas they moved in a controlle d 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 con struct a two-particle column by placing one particle directly on top of ano ther one.