Lingjun Geng,Jingcheng Huang,Haowei Dong,Haifang Wang,Rui Xu,Zhiping Yu,Ibrahim A. Darwish,Yemin Guo,Xia Sun
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@SnS 2 @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 -1.00×10 4 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.
Xue Wang,Zhaoyang Zhou,Shuang Jiang,Qi Sun,Xianlu Lei,Yong Xie,Tao Le
Norfloxacin (NOR) has been widely applied in animal husbandry and aquaculture because of its potent antibacterial activity, broad-spectrum efficacy and cost-efficient. Nevertheless, its inappropriate use may result in teratogenic and carcinogenic risks to humans, making the accurate and rapid detection of NOR residues in food critically important. In this study, a strong affinity (Kd = 84 nM) and high selectivity anti-NOR aptamer was obtained by screening with Graphene Oxide Systematic Evolution of Ligands by Exponential Enrichment (GO-SELEX), and a colorimetric aptasensor was fabricated. The limit of detection of the aptasensor was 1.04 ng/mL, and the linear range was 1.56-100 ng/mL. Average recoveries of the aptasensor in shrimp and fish sample analyses ranged from 89.33% to 103.24%, accompanied by coefficients of variation from 3.63% to 9.43%, indicating good analytical precision and accuracy. The aptasensor constructed in this study showed high consistency with the High-Performance Liquid Chromatography (HPLC) for NOR detection, indicating that it is an efficient and promising sustainable strategy for monitoring NOR.
As a promising recognition molecule, aptamers are widely used in the field of small molecule detection. However, few reports are available on the key factors governing successful aptamer selection. To improve the success rate, the melamine-specific aptamer served as a model to investigate critical factors in library-immobilization-based SELEX methods (GO-SELEX and Beads-SELEX). The results indicated that non-ionic surfactants significantly enhanced the desorption of ssDNA from the graphene oxide (GO) surface in Mode one of the mimic GO-SELEX (GO-facilitated library immobilization and target-induced aptamer release). In contrast, in Mode two of the mimic GO-SELEX, where GO was used solely for non-target-binding aptamer removal, and significant non-specific binding between ssDNA and GO compromised the enrichment efficiency of target-specific sequences, necessitating the use of high target concentrations during SELEX. Similarly, in Beads-SELEX, high target concentrations were required to release specific ssDNA, which also led to a small amount of non-specific ssDNA co-release during the procedures. Other SELEX conditions were also compared and constructive suggestions were provided for facilitating the successful aptamer selection. In summary, this study provided SELEX condition optimization guidance for the selection of aptamers specific to small molecules, when different library-immobilized SELEX methods were performed.
危险品化学品经营许可证（带存储）