Spectroscopic and design considerations for quartz-bound Au nanoparticle SERS substrates in chemical and biological detection

Abstract

Surface enhanced Raman spectroscopy (SERS) and spatial characterization of quartz-bound Au nanoparticle substrates has been used to assist the improvement of analytical sensitivity and limits of detection. SERS enhancement is significantly affected not only by a substrate's surface morphology but also laser-analyte orientation as well as matrix effects caused by non-analyte and non-metal substrate compounds. The use of Au hydrosols to fabricate better performing SERS substrates to detect chemical and/or biological agents has been an area of active and widespread research, but to date, the impact of matrix effects from spectral interferers introduced during fabrication on analytical sensitivity and limits of detection is not well understood. Experiments varying the depth of collection (observation) volume with respect to R6G on the substrate show high variability in analyte signal to noise ratios (S/N) well as high variability in background due to matrix effects from varying influences of the substrate non-metal components. Of the many post-fabrication design factors affecting SERS substrate sensitivity, characterization of matrix effects caused by vertical changes in observation volume near the analyte-substrate interface will improve analytical sensitivity and limits of detection.