基于金核铂壳纳米酶比色检测白菜中有机磷农药新方法研究

Development of novel colorimetric detection of organophosphorus pesticides in cabbage based on gold core-platinum shell nanozyme

目的基于纳米模拟酶活性抑制策略开发具有特异性的有机磷农药分析新方法。方法基于金核铂壳纳米粒子(gold core-platinum shell nanoparticle,Au@Pt NPs)可以与甲拌磷、氧乐果和乐果3种有机磷农药发生作用从而使其类过氧化物酶活性被特异性抑制,建立3种有机磷农药比色检测方法。结果透射电镜(transmission electron microscope,TEM)、X射线能谱仪(energy dispersive spectrometer,EDS)结果表明,3种有机磷农药可通过Pt-S键吸附到Au@Pt NPs表面,不仅遮蔽了Au@Pt NPs表面的活性位点,还促使了Au@Pt NPs的团聚,最终导致Au@PtNPs的催化活性降低。通过3,3’,5,5’-四甲基联苯胺(3,3’,5,5’-tetramethylbenzidine,TMB)和过氧化氢(H2O2)的显色体系将农药的抑制作用信号放大,甲拌磷、氧乐果和乐果的比色检测半抑制浓度(50%inhibiting concentration,IC)值分别为0.38、0.41和5.21μg/mL,检出限为19.7、24.2和13.4 ng/mL,且表现出一定的特异性。结论该方法操作简单、具有一定的特异性,可用于白菜中甲拌磷、氧乐果和乐果的检测。

Objective To develop a novel specific method for the analysis of organophosphorus pesticides based on inhibition strategies of nanomaterial enzyme mimetics activity. Methods The colorimetric detection for 3 kinds of organophosphorus pesticides including phorate, omethoate and dimethoate, was developed based on that the gold core-platinum shell nanoparticles(Au@Pt NPs) could react with the 3 kinds of organophosphorus pesticides, which resulted in the specific inhibition of peroxidase-like activity of Au@Pt NPs. Results The transmission electron microscope(TEM) and energy dispersive spectrometer(EDS) results showed that 3 kinds of organophosphorus pesticides were adsorbed to Au@Pt NPs surface through Pt-S bond, which not only covered the active site on Au@Pt NPs surface, but also led to the aggregation of Au@Pt NPs, so the catalytic activity of Au@Pt NPs decreased. The inhibition signals of pesticides were amplified by the chromogenic system of 3,3’,5,5’-tetramethylbenzidine(TMB)and hydrogen peroxide(HO), the 50% inhibiting concentration(IC) values of phorate, omethoate and dimethoate were 0.38, 0.41 and 5.21 μg/mL, respectively, the limits of detection were 19.7, 24.2 and 13.4 ng/mL, respectively,and showed certain specificity. Conclusion The method is simple in operation and has certain specificity, and can be used for the determination of phorate, omethoate and dimethoate in cabbage.