Background-Free Bottom-Up Plasmonic Arrays with Increased Sensitivity, Specificity and Shelf Life for SERS Detection Schemes

In utilizing the exceptional optical properties of metallic nanoparticles, surface enhanced Raman spectroscopy (SERS) is an excellent candidate for analytical detection schemes due to its molecular specificity and high sensitivity. To record reliable SERS signals, impurifications on the metallic surface contributing to the overall SERS signal, have to be removed. In this context, it is important to improve the nanostructures’ quality to implement SERS in routine analytical applications. Here, we report about an easy to handle and fast protocol for the generation of SERS active nanoparticles by enzymatically reducing silver ions to their elementary state and oxidizing hydroquinone (HQ) to p-benzoquinone (p-BQ). However, these SERS substrates lead to a strong background signal overlapping with the actual analyte Raman bands. In order to quench this background signal and to protect the silver nanoparticles from oxidation we covered metallic nanoparticles with a dielectric layer of alumina (Al2O3) by applying...