Synthesis of hollow gold nanoparticles on the surface of indium tin oxide glass and their application for plasmonic biosensor.

Hollow gold nanoparticles (HGNs) deposited on the surface of transparent indium tin oxide (ITO) glass have been synthesized. The silver nanoparticles were firstly electrodeposited directly on the ITO surface as a template without any organic ligands or surfactants. Then these silver nanoparticles were taken as sacrificial templates and the HGNs were obtained by Galvanic replacement reaction between HAuCl4 solution and silver nanoparticles. The localized surface plasmon resonance (LSPR) peak of HGNs was located at near infrared region of ~800 nm, which was largely red-shifted as compared to silver nanoparticles as a template. Moreover, the refractive index sensitivity of HGNs was enhanced to 277 nm per refractive index unit, which was also much higher than that of silver nanoparticles deposited on ITO substrate. The "clean" surface of HGNs could be further functionalized by special biomolecules and applied to fabrication of LSPR biosensors. This approach provides a potential opportunity as LSPR biosensors for chemical or biological analysis especially on tissue and blood samples.