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Anal Chim Acta. 2011 Feb 14;687(1):89-96. doi: 10.1016/j.aca.2010.12.018. Epub 2010 Dec 21.

Label-free capacitive immunosensor based on quartz crystal Au electrode for rapid and sensitive detection of Escherichia coli O157:H7.

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1
College of Biosystems Engineering and Food Science, Zhejiang University, 268 Kaixuan Road, Hangzhou 310029, China.

Abstract

A label-free capacitive immunosensor based on quartz crystal Au electrode was developed for rapid and sensitive detection of Escherichia coli O157:H7. The immunosensor was fabricated by immobilizing affinity-purified anti-E. coli O157:H7 antibodies onto self-assembled monolayers (SAMs) of 3-mercaptopropionic acid (MPA) on the surface of a quartz crystal Au electrode. Bacteria suspended in solution became attached to the immobilized antibodies when the immunosensor was tested in liquid samples. The change in capacitance caused by the bacteria was directly measured by an electrochemical detector. An equivalent circuit was introduced to simulate the capacitive immunosensor. The immunosensor was evaluated for E. coli O157:H7 detection in pure culture and inoculated food samples. The experimental results indicated that the capacitance change was linearly correlated with the cell concentration of E. coli O157:H7. The immunosensor was able to discriminate between cellular concentrations of 10(2)-10(5) cfu mL(-1) and has applications in detecting pathogens in food samples. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were also employed to characterize the stepwise assembly of the immunosensor.

PMID:
21241851
DOI:
10.1016/j.aca.2010.12.018
[Indexed for MEDLINE]
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