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.