基于杂化脂肪酶抑制的有机磷均相电化学传感检测

    Homogeneous electrochemical sensing detection of organophosphorus based on hybrid lipase inhibition

    • 摘要: 为实现对有机磷农药(organophosphorus pesticides, OPs)的快速灵敏检测并减少其对乙酰胆碱酯酶抑制所带来的神经毒性风险,该研究基于OPs对脂肪酶水解棕榈酸对硝基苯酯能力的抑制作用,采用酶-无机杂化纳米技术合成具有高比表面积、高催化活性及过氧化物酶模拟活性的杂化脂肪酶(BCL@Zn-hNF),并通过电化学沉积构建纳米金修饰电极(AuNPs/Au),形成均相电化学传感体系。结果表明,该传感器在3.80×10−8~4.56×10−5 mol/L范围内具有良好线性关系,检出限达到1.13×10−9 mol/L,且在甲基对硫磷检测中具有优异的重现性、稳定性及抗干扰性,在多种实际样品中的回收率较高,展现出该均相电化学传感体系灵敏、低成本检测OPs的应用潜力。

       

      Abstract: Organophosphorus pesticides (OPs) are widely employed in agricultural production due to their high efficacy and broad-spectrum activity; however, their potent inhibition of AChE can induce neurotoxicity and other toxic effects, posing a serious threat to food safety and environmental security. Consequently, reliable monitoring of organophosphorus residues in food and water sources has garnered increasing attention. Traditional detection methods for organophosphates, such as gas chromatography, liquid chromatography, and mass spectrometry, offer high sensitivity and accuracy. However, they typically require expensive equipment and complex operation, making rapid on-site detection challenging. Electrochemical biosensors, however, combine the high specificity of enzyme-substrate interactions with the simplicity and cost-effectiveness of electrochemical detection, presenting a highly promising detection approach. Nevertheless, conventional sensors based on acetylcholinesterase or organophosphorus hydrolase suffer from poor stability and high preparation costs. To address this, this study developed a homogeneous electrochemical sensing system combining a hybrid lipase (BCL@Zn-hNF) with a gold nanoparticle-modified electrode (AuNPs/Au). Leveraging the inhibitory effect of organophosphorus pesticides on the lipase's ability to hydrolyse p-nitrophenyl palmitate, this system enables the detection of OPs. BCL@Zn-hNFs were prepared via self-assembly of Burkholderia cepacia lipase with Zn2+, yielding three-dimensional flower-like nanostructures characterised by high specific surface area, catalytic activity, and peroxidase-like properties. AuNPs were deposited onto a bare gold electrode via electrodeposition, with optimisation of electrode assembly method, AuNP size, and electrodeposition cycles to enhance electron transfer efficiency and surface activity. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the floral morphology of BCL@Zn-hNFs, whilst Fourier transform infrared spectroscopy (FT-IR) validated successful coordination bond hybridisation. Electrochemical impedance spectroscopy (EIS) further demonstrated the significantly enhanced electron transfer performance of the AuNPs/Au electrode. Results indicated that the AuNPs/Au modified electrode exhibited optimal electron transfer efficiency (ks=1.15/s) and effective surface area (0.23 cm2) when AuNPs size was 14.18 nm and the number of electrodeposition cycles was 20. Leveraging the high catalytic activity of BCL@Zn-hNF and the protective effect of the homogeneous system on enzyme conformation, the constructed homogeneous electrochemical sensing system demonstrated outstanding performance in detecting methyl parathion (MP). It exhibited a broad linear detection range of 3.80×10−8~4.56×10−5 mol/L and a low detection limit of 1.13×10−9 mol/L. In pH, temperature, and storage stability tests, the residual activity of BCL@Zn-hNFs significantly outperformed free lipase, retaining over 80% of its initial activity after 28 days of storage, further validating its tolerance in complex detection environments. Furthermore, in practical sample detection, validation through spiking tap water, vegetables, and fruit samples with MP yielded recovery rates ranging from 100.37%~134.62%, with RSD<5%. Concurrently, this electrochemical sensing system demonstrated excellent reproducibility (RSD =1.91%), stability (retaining 90.96% activity after 30 days), and resistance to interference. In summary, this study established a novel homogeneous electrochemical sensing platform. Compared to traditional enzyme-based sensors, this method offers the advantages of high sensitivity, high stability, and low cost. It provides a promising approach for detecting organophosphorus pesticide residues, highlighting the application potential of enzyme-based electrochemical biosensors in food safety monitoring and environmental analysis.

       

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