LAUSR

In this study, the effects of the sizes of AgNPs and the resulting hotspot nanogaps on the SERS spectra have been studied extensively. The optimal condition of AgNPs/mesoPS active substrate for efficient, high reproducibility and excellent stability was obtained at lowest nanogaps. The maximum EFs of about 1.4 × 105 and 1.2 × 105 were obtained for 10− 5 M Cy3 dye solution concentration at two average AgNP sizes of (282.95 and 338.1) nm and corresponding average nanogaps of (22.28 and 26.43) nm respectively. The better reproducibility with minimum variation of SERS intensity of about (14%) after six month aging in air was obtained for more uniform AgNPs deposited on mesoPS surface with peak nanogaps of 10 nm at 8 min immersion time. The detection limit for Cy3 dye molecules adsorbed on AgNPs/mesoPS active substrate prepared at 8 min has been evaluated as 10− 14 M and the high EF of about 5.3 × 1012 was obtained when using this concentration.