Electrochemical immunoassay of E. coli in urban sludge using electron mediator-mediated enzymatic catalysis and gold nanoparticles for signal amplification
Wenjie Lu , Rongjin Xu , Xinai Zhang , Jianzhong Shen , Changfeng Li
Chemical Research in Chinese Universities ›› 2018, Vol. 34 ›› Issue (1) : 101 -106.
Electrochemical immunoassay of E. coli in urban sludge using electron mediator-mediated enzymatic catalysis and gold nanoparticles for signal amplification
An electrochemical immunosensor was developed for sensitive assay of E. coli in urban sludge, in which electron mediator-mediated enzymatic catalysis and gold nanoparticles(AuNPs) were utilized for signal amplification. The immnuosensing platform chitosan-thionine(chit-thio)/poly(amidoamine) dendrimer-encapsulated AuNPs [PAMAM(Au)] composites were first prepared from chit-thio and PAMAM(Au) using the layer-by-layer method to provide a matrix for high-stability and high-bioactivity bindings of the capture antibody(cAb). Moreover, the {dAb-AuNPs-HRP} nanoprobes were designed to exploit the amplification effect of the carrier AuNPs due to the loading amounts of horseradish peroxidase(HRP) and the detection antibody(dAb). The sandwich-type immunoassay was then successfully used to assay E. coli based on the oxidation of thionine as a result of H2O2-induced enzymatic catalytic reaction by HRP. This study presents a powerful tool in electrochemical immunoassay for E. coli detection with rapid response, high-sensitivity and high-specificity, providing a potential new tool for feasibility assessment of sludge recycle.
Electron mediator / Enzymatic catalysis / Electrochemical immunosensor / E. coli / Urban sludge
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