基于MOCPs-MWCNTs的大肠杆菌电化学免疫传感器

Electrochemical Immunosensor Assay(EIA) of E. coli O157:H7 Based on MOCPs-MWCNTs with Highly Efficient Antibody Immobilization

食源致病菌引起的食品安全问题已成为全世界关注的焦点。设计了一种基于多壁碳纳米管(MWCNTs)-有机配位聚合物(MOCPs)高效固定抗体的大肠杆菌电化学免疫传感器。利用NaAuCl_4与1,4-苯二硫醇(BDT)反应生成金属有机配位聚合物,同时在BDT的还原作用下生成大量纳米金,并包埋大量吸附在MWCNTs表面的大肠杆菌抗体,最终将抗体高效包埋在MOCPs-MWCNTs中,基于MOCPs-MWCNTs固定抗体研制修饰电极,在目标物大肠杆菌O157:H7的存在下,辣根过氧化氢酶标记的抗体(HRP-Ab)随后特异性捕获于电极表面形成典型夹心结构,通过HRP催化底物产生电化学信号从而实现大肠杆菌O157:H7的检测。MOCPs-MWCNTs特有的高比表面积高效固定了大量抗体,增加了传感器结合抗体的效率并提高了传感器的灵敏度。该传感器对大肠杆菌O157:H7的检测线性范围为67~6.7×10~6cfu/mL,最低检出限为40 cfu/mL。

Microbiological contamination caused by food-borne diseases has become a major public health problem of the world.A novel electrochemical immunosensor assay（EIA） for high sensitive and specific detection of Escherichia coli O157： H7 was developed.A new nanocomposites with multi-walled carbon nanotubes（MWCNTs） embedded inmetal-organic coordination polymers（MOCPs） was successfully prepared as highly efficient matrices of capturing antibody immobilization for sensitive electrochemical biosensing.In the presence of target E.coli O157： H7,horse radish peroxidase（HRP）-labeled antibody was captured on the electrode surface to form a sandwich-type system via the specific identification.As a result,E.coli O157： H7 detection was realized by outputting a redox current from electro-reduction of hydrogen peroxide reaction catalyzed by HRP.In the assay,the combination of the unique properties of MWCNTs and MOCPs can not only accelerate electron transfer on the electrode interface,but also provide an excellent scaffold for the conjugation of capture antibody.Meanwhile,adopting the MWCNTs-MOCPs materials significantly improved the target capturing efficiency and enhanced the sensitivity of the biosensor.The results revealed that the calibration plot obtained for E.coli O157： H7 was approximately linear from 67 cfu/mL to 6.7 × 10^6cfu/mL with the limit of detection of 40 cfu/mL.In addition,the biosensor was successfully applied to quantitative assay of E.coli O157： H7 in synthetic sample（milk）.Hence,the developed electrochemical-based immunosensor might provide a useful and practical tool for E.coli O157： H7 determination and related food safety analysis and clinical diagnosis.