Development of gold–silica composite nanoparticle substrates for perchlorate detection by surface-enhanced Raman spectroscopy

Abstract

Surface-enhanced Raman spectroscopy (SERS) holds promise for rapid, in situ detection of perchlorate (ClO 4 −) in the environment if sensitive and reproducible SERS substrates can be developed. In this study, new, functionalized gold–silica (Au–SiO 2) composite nanoparticles were synthesized and used as SERS substrates for ClO 4 − detection. These nanoparticles were composed of a silica core with Au nanoparticles grafted onto the SiO 2 spheres by in situ chemical reduction of AuCl 4 − or physisorption of Au colloids. Chemical coupling agents with such functional groups as –N +(CH 3) 3 and –NH 3 +/–NH 2 were used to enhance perchlorate sorption onto the substrate and therefore the detection of ClO 4 −. These new substrates were found to be optically stable and provide a greatly enhanced surface plasmon or SERS, resulting in a detection limit as low as 10 −6 M ClO 4 − (0.1 mg/L) in water.