Silver nanowire/gold nanosphere binary plasma-assembled membranes for sensitive SERS detection of homocysteine.

Silver nanowire (Ag NW)/gold nanosphere (Au NS) binary plasma films were prepared using plasma coupling between Ag NWs and Au NSs. The plasma films formed by combining these two noble metals showed better sensitivity for SERS detection with a minimum detection concentration of 10-8 M for R6G compared to pure Ag NWs or Au NSs. After rational optimisation of the substrate preparation process, the substrate showed good homogeneity, reproducibility and stability. We perform an indirect detection of homocysteine (Hcy) through a specific reaction of Hcy with o-phthalaldehyde (OPA). The lowest detectable concentration of Hcy was 5 × 10-9 M. The recoveries of Hcy were 94.53 ~ 103.43% with the relative standard deviations (RSDs) of 2.53%, 9.21% and 12.26%, respectively, in the spike recovery experiments. With good selectivity and accuracy for Hcy detection, this plasma film provides an idea for the detection of disease markers in serum.