▎ 摘　　要

Graphene oxide (GO) serving as an ultrathin, seamless and passivated shell has been intensively investigated in shell-isolated surface-enhanced Raman scattering (shell-isolated SERS) research field. Here we report a novel and effective SERS platform based on GO wrapped flower-like Ag microparticles (Ag@GO). GO layers were efficiently enclosed around cysteamine functionalized Ag particles by electrostatic interactions. The morphology of flower-like Ag microparticles could be optimized by varying the reaction conditions such as growth temperature and the amount of reagents. The prepared Ag@GO SERS active substrates exhibited much higher stability wherein the SERS intensities of Ag@GO hybrids were only decreased by 16 5% after 50 days exposure under ambient condition, comparing with a 69 +/- 10% decrease for bare Ag particles. Furthermore, the SERS sensitivity of rhodamine 6G (R6G) on Ag@GO hybrids was improved 3.5 times due to the chemical enhancement from transparent GO shell. The excellent reproducibility with average intensity variations less than 5% was also achieved. Most importantly, eliminating an extra surface modification steps, Ag@GO composite substrates demonstrated a high enrichment capability and remarkable SERS response toward polychlorinated biphenyls (PCBs), which have weak affinity on noble metal surface. Specifically, GO wrapped Ag particle hybrid could offer spectroscopic identification of two PCB congeners in mixed solution, showing promising potential for practical applications of single-particle SERS-based sensing and on-site monitoring in environment. (C) 2016 Elsevier B.V. All rights reserved.