Sensitivity Enhancement by Au Nanoparticles in Surface Plasmon Resonance Chemical Sensors

We investigated the sensitivity enhancement in chemical sensors by coupling Au nanoparticles that have the specific size and surface density on sensor chips as those found in label-free detection systems. The Au particles with 10, 30, 60 nm diameter were conjugated by amine groups of cystamine modified chips. The surface density of Au particles was controlled by the reaction time and the concentration of the solution containing the particles. In order to investigate the sensitivity enhancement, we compared the resonance angle shifts with or without Au particles in a methanol aqueous solution. We know that the sensitivity depends on the size and surface density of particles. The sensitivity increased by 57% with the adsorption of 30 nm diameter particles and low surface density due to the coupling effect of localized surface plasmon derived by the size and density of specific Au nanoparticles and surface plasmon waves.