Rapid In Situ SERS Analysis of Pesticide Residues on Plant Surfaces Based on Micelle Extraction of Targets and Stabilization of Ag Nanoparticle Aggregates

A structure of polyurethane micelle/Ag nanoparticle (Ag NP) cluster was fabricated as surface-enhanced Raman scattering (SERS) substrate for in situ extracting organic compounds on the surface of different matrixes, in which polyurethane micelles acted as the host material to capture target molecules and stabilize nanoparticle cluster. This method provided stable aqueous suspensions of Ag NP cluster due to the amphiphilic properties of polyurethane. We demonstrated SERS-based in situ detection of pesticides on vegetables and fruit skin, by simply dropping polyurethane micelle/Ag NPs substrate on the sample surface where the target molecules could be detected without a previous elution and extracting. The obtained results showed that this polyurethane micelle/Ag NP cluster substrate had excellent SERS performance for pesticide molecules with ideal stability and reproducibility. With further optimization, the limit of detection of 0.03 μg/mL acetamiprid, 0.08 μg/mL phosmet, and 0.002 μg/mL thiabendazole was obtained, respectively.