Versatile Approach to Self-Assembly of Surface Modified Nanoparticles into SERS-Active Nanoclusters

A versatile method is invented to self-assemble gold nanoparticles (GNPs) into nanoclusters (NCs) of various morphologies. By storing the particles in toluene, a highly non-polar solvent, under conditions that ensure particle stability, the success rate of subsequent assembly can be enhanced. Additionally, conducting particle self-assembly at a stirring speed of 200 rpm allows the NCs to maintain a spherical shape. The relative standard deviation (RSD) of Raman spectral peaks of multiple NCs used as surface-enhanced Raman spectroscopy (SERS) substrates is calculated to be less than 10%, effectively addressing the issue of low repeatability when using NCs as SERS substrates. Furthermore, even at an analyte concentration reduced to 10-9 m, a SERS characteristic peak intensity of approximately 2 x 103 is measurable, demonstrating the high sensitivity of the assembled structures. Finally, by detecting SERS signals from NCs of varying sizes, the intensities of characteristic peaks tend to converge, eliminating the influence of morphology and size on SERS detection. Self-assembly of gold nanoparticles (GNPs) of different shapes into stable spherical nanoclusters (NCs) ensures stability. The relative standard deviation (RSD) of Raman peak intensity is less than 10%, improving reproducibility. Even at low analyte concentrations, intensities above 2 x 103 with high surface-enhanced Raman spectroscopy (SERS) sensitivity are achievable. Peak intensities from NCs of different sizes converge, eliminating the influence of morphology and size. image