Transformation from gold nanoclusters to plasmonic nanoparticles: A general strategy towards selective detection of organophosphorothioate pesticides.

Luminescent gold nanoclusters (AuNCs) synthesized using non-thiolate DNA ligands were reported to show both optical and structure responses toward diethyposphorthioate (DEP) derived from the hydrolysis of chlorpyrifos (CP). After incubation of AuNCs with DEP, the non-thiolate DNA ligands were immediately replaced and the tiny AuNCs with ultrasmall size transformed gradually to plasmonic nanoparticles, which resulted in significant luminescence quenching of the AuNCs, offering a new possibility to selectively detect organophosphorothioate pesticides that could be easily hydrolyzed to form the special structures such as DEP containing two binding sites (e.g. S and O atoms). Therefore, selecting CP as a model analyte, we here developed a general strategy for the construction of a novel chemosensor for the determination of CP using the non-thiolate DNA coated AuNCs as an optical probe. Based on aggregation-induced luminescence quenching, this strategy exhibited highly sensitive and selective responses towards CP with a limit of detection (LOD) of 0.50μM, and was applied successfully to the analysis of CP in real sample. More interestingly, this facile strategy could easily distinguish CP from other thiol reagents through solution color change in spite of the existence of the coordination between Au and S atom for both of them, and the response mechanisms for them were studied in detail. In additional, it could be extended to detect the other organophosphorothioate pesticides with the similar structure as CP, which exploits a new platform for the construction of chemosensor and application.