Quantitative Detection with Surface Enhanced Raman Scattering (SERS) Using Self-Assembled Gold Nanoparticle Cluster Arrays

Abstract

We analysed sensitivity of high-density arrays of self-assembled gold nanoparticle clusters towards trace analyte detection and quantitative determination by surface enhanced Raman spectroscopy (SERS) employing an aromatic thiol as probe molecule. Periodic nanoscale arrays of gold nanoparticle clusters consisting of an average of 18 nanoparticles per cluster, and exhibiting mean inter-particle and inter-cluster separations below 10 nm were prepared using electrostatic self-assembly on block copolymer templates. The concentration dependent scaling of SERS intensities and the lowest detection limits on the cluster arrays on silicon substrate was probed using 1-naphthalenethiol (NT) as test molecule. The substrates show a detection limit of 10 nM along with high sensitivity to changes in NT concentration, which we attribute to high density of hot-spots uniformly organised across the surface. The capability for facile realisation of such arrays without a clean room environment or expensive tools makes the approach suitable for adoption for economic and high-performing SERS sensors.