Construction of a silver nanoparticle SERS aptamer-based sensor and its specific recognition of diazinon

A novel biosensing strategy based on the synergy of aptamer molecular recognition and surface-enhanced Raman spectroscopy (SERS) has been developed to address the growing problem of groundwater and soil contamination by the organophosphorus pesticide diazinon (DZN). By combining a high-affinity aptamer with a plasmonic resonance-enhanced substrate, a SERS biosensing interface with single-molecule detection capability was successfully constructed, and the electrochemical surface-enhanced Raman spectroscopy (EC-SERS) method using AgNPs-modified screen-printed electrodes (SPEs) was also used for sensitive detection of DZN. The results showed that the constructed SERS aptamer sensor was able to specifically identify diazinon in the system where multiple interfering pesticides coexisted, and the detection limit of the sensor for diazinon was up to 5.33 × 10^-10 M. The intensity of the characteristic peaks (602 cm^-1) showed a good linear response with the concentration of DZN, which demonstrated very high detection sensitivity and specific identification function. The proposed EC-SERS method significantly improves the SERS signals of pesticides by potentiometrically modulating the plasmonic resonance coupling effect at the interface of AgNPs-modified electrodes, inducing an orientationally regularised arrangement of DZN molecules. The SERS aptasensor was used to detect diazinon in wastewater and subsurface soil with good recoveries (83.20%-117.78%), which were in good agreement with the results obtained by high-performance liquid chromatography. The results demonstrated that the SERS aptasensor has good sensitivity, stability, simplicity of operation, and specific identification, which provides a solution with ultra-sensitive response, rapid analysis, and strong anti-interference for the detection of trace pesticide.