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

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• 作者：Dujuan Li^a ; Yangyang Feng^a ; Ling Zhou^a ; Zunzhong Ye^a ; Jianping Wang^a ; ^{jpwang@zju.edu.cn} ; Yibin Ying^a ; Chuanmin Ruan^b ; Ronghui Wang^b ; Yanbin Li^b
• 关键词：Escherichia coli O157 ; H7 ; Capacitive immunosensor ; Self-assembled monolayers ; Cyclic voltammetry ; Electrochemical impedance spectroscopy
• 刊名：Analytica Chimica Acta
• 出版年：2011
• 出版时间：14 February 2011
• 年：2011
• 卷：687
• 期：1
• 页码：89-96
• 全文大小：493 K

文摘

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 10²–10⁵ 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.