Assemble of high-density gold nanodots on TiO ₂ substrate for surface-e nhanced Raman spectroscopy

The cost-effective assemble of Au nanodots on TiO ₂ substrate over a large domain for high-sensitivity and reproducible surface enhanced Raman spectroscopy (SERS) is demonstrated. Au nanoparticles of defined size are immobilized on TiO ₂ to form high-density Au nanodots with removal of surface ligand meanwhile. The Au nanodots exhibit pronounced surface Plasmon resonance (SPR) due to strong interparticle coupling and hot spots formed in these gaps which enable large amplification of SERS signals. Using the Au nanodots (3.8 nm) assemble a 5 times stronger SERS enhancement than larger Au nanoparticles (NPs) of same Au amount is experimentally demonstrated. The facile fabrication of SERS-active substrate over a large area and cost-effective character enable this high-density Au nanodots on TiO ₂ substrate practical application for SERS detection of trace amount of molecule of interest.