Label-free surface-enhanced Raman scattering quantitative analysis of dual electromagnetically enhanced flexible...

We designed and synthesized a flexible Au@PB@Ag NPs-CFs surface-enhanced Raman scattering (SERS) substrate with self-calibration functionality. Compared to traditional core-shell structured substrates with internal standards, our proposed substrate, which fully encapsulates a Prussian Blue (PB) layer, exhibits dual electromagnetic enhancement effects on both the PB self-calibration signal and the pesticide signal due to the localized surface plasmon resonance within the silver shell cavity. The results show that after signal calibration, the relative standard deviation decreased from 30.34 % to 11.24 %. The water-dispersible Au@0.8 PB@Ag NPs loaded on chitosan demonstrated extremely high sensitivity for the detection of alcohol-soluble pesticides thiram and thiabendazole, with detection limits as low as 0.015 μM and 0.098 μM, respectively. Additionally, due to the substrate's flexibility and excellent uniformity, it effectively addresses the "coffee ring" effect and enables quantitative detection through direct swabbing, with spiked recovery rates ranging from 81 % to 116.6 %.