Surface-enhanced Raman spectroscopy effective substrates based on silver particle layers: Analytical applications, spectral reproducibility, benefits, and future developments

This work focuses on the modification of surfaces of Al2O3 and cellulose impregnated by polyethyleneimine to increase the deposition effectiveness, size, and morphological characteristics of the deposited silver particles. Modifications of substrates were done by polydopamine layer formation on substrate surfaces or by surface activation through immersion in SnCl2 solution. The silver particle layers were done by deposition from a liquid phase using ultrasound-assisted reduction of silver ammonia complex ([Ag(NH3)2]+) by maltose or glucose which served as reductants. Prepared layers were in some cases subsequently re-crystallized by NaCl solution which led to formation of the larger silver particles or aggregates. The influence of substrate surface modification and re-crystallization of the silver particles on SERS efficiency was evaluated by enhancement factor calculations. Their values reached up to 1.4·106 for 780 nm and 8.1·105 for 532 nm lasers.