(395h) Carbon Black-Gold Nanoparticles for Detection of Analytes Using Surface Enhanced Raman Scattering
Surface-enhanced Raman scattering (SERS) is a powerful technique for the detection of a variety of molecules at very low concentrations. We have developed irregularly shaped gold nanoparticles using a carboxyl-terminated carbon black (CB) nanoparticles as a template. The CB particles were coated with the cationic polyelectrolyte poly-L-lysine (PLL) and exposed to a tetrachloroauric acid solution. Gold - carbon black (AuCB) particles were formed by the reduction of gold chloride ions that concentrated on the surfaces of the PLL. The morphology of the gold on the AuCB can be modified using different PLL concentrations,. The plasmon resonance can then be matched to the incident laser wavelength, thus greatly enhancing Raman signals coming from analytes in the vicinity of the gold surface. We used these AuCB particles to detect a wide range of analytes, including 4-nitrobenzene thiol, and nitrate and sulfate ions in a mixture. The limits of detection were well below that obtained by other SERS particles.