Direct readout SERS multiplex sensing of pesticides via gold nanoplate-in-shell monolayer substrate

Gold nanoplate-in-shell with high purity has been prepared via a facile two-step synergistic protocol, i.e., partial reduction followed by galvanic reaction at ambient condition. Moreover, the synthetic strategy has been suggested as a versatile approach for fabricating nanogold-in-shell with different morphology, e.g., nanosphere or nanorod etc. Controlling stoichiometry between Ag and metastable AuCl2- can lead to transition of gold nanoplate-in-shell nanostructure from thin-wall, porous, thick-wall to multipod. SERS comparisons of monolayer gold nanoplate-in-shell substrate via layer-by-layer approach, suggest that SERS activity of porous nanoplate-in-shell is obviously superior to the other nanostructures. Moreover, direct readout SERS for multiplex recognition of pesticides can be obtained by using porous nanoplate-in-shell monolayer substrate. As a result, sensitive SERS detection of the pesticides, i.e., the limit of detection for thiram and chlorothalonil, respectively, which are 12.29 nM and 30.15 nM, can be achieved. (C) 2014 Elsevier B.V. All rights reserved.