Immobilization of gold nanoparticles on optical waveguides with organosilane monolayer

Synthesis of Au nanoparticles (NPs) and their immobilization on optical waveguide (OWG) made of quartz plate were carried out aiming at application to sensing. Au NPs with diameters of ∼5 nm and ∼20 nm were synthesized by reduction of tetrachloroaurate ions with borohydride and immobilized on quartz OWG coated with monolayer of organosilane. With the OWG spectroscopy, the surface plasmon absorption of the Au NPs immobilized on OWG was suggested to be influenced by the particle size and the interparticle distance and to response to the refractive index of nanoparticle proximity sensitively.