GO-SELEX-enhanced dual-recognition sensor for highly specific detection of azamethiphos

Organophosphorus pesticides (OPs) have attracted attention due to their widespread application in agriculture and public health sector. Among them, azamethiphos (AZA) may pose risks to non-target organisms and human health through food chain accumulation. Therefore, establishing a highly sensitive and specific detection method of AZA is of great significance for ensuring food safety and ecological protection. In this study, based on graphene oxide-SELEX technology, an aptamer (Apt) with specific recognition for AZA (K_d=26.27±1.27 nM) was screened for the first time. This aptamer was subsequently integrated with molecularly imprinted polymers to construct a dual-recognition electrochemical sensor, leveraging the complementary advantages of both recognition elements. This dual-recognition strategy enabled the synergistic enhancement of specific recognition ability, effectively reducing interference from non-target substances and improving sensor selectivity and accuracy. Additionally, a doping strategy was adopted to modify the electrode surface with AuNPs@SnS₂@ZnCo-MOF nanocomposites, improving electron transfer efficiency and providing abundant active sites, thereby significantly enhancing the electrochemical signal response. The sensor exhibited a wide detection range (1.00×10^-2-1.00×10⁴ ng/mL) and a low limit of detection (3.33×10^-3 ng/mL), while also demonstrating excellent stability and specificity. In summary, this study developed a highly efficient, sensitive and selective electrochemical sensor, providing a novel strategy for the rapid detection of AZA and other organophosphorus pesticides, with broad application prospects in food safety and environmental monitoring.