Carboxyl-functionalized Ag@SiO2 nanoparticle films for highly sensitive and selective surface-enhanced Raman scattering applications

We demonstrate a surface-enhanced Raman scattering (SERS) sensor based on carboxyl-functionalized core-shell structure of Ag@SiO2 nanoparticles (NPs) active substrate. For selective molecular capturing, the active substrate was functionalized by carboxyl terminal groups to form a negatively charged surface. Experimental results indicate that the SERS sensitivity of the NPs was improved significantly for detecting the positively charged substances. The experimental results provide a potential method for preparing highly sensitive biochemical sensors, especially in the application of recognizing specific molecules accurately.