Self-assembled monolayers-based immunosensor for detection of Escherichia coli using electrochemical impedance spectroscopy

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• 作者：Ping Geng ; Xinai Zhang ; Weiwei Meng ; Qingjiang Wang ; Wen Zhang ; Litong Jin ; Zhen Feng ; Zirong Wu
• 关键词：E. coli ; Immunosensor ; Electrochemical impedance spectroscopy
• 刊名：Electrochimica Acta
• 出版年：2008
• 出版时间：30 May 2008
• 年：2008
• 卷：53
• 期：14
• 页码：4663-4668
• 全文大小：561 K

文摘

An electrochemical impedance immunosensor for the detection of Escherichia coli was developed by immobilizing anti-E. coli antibodies at an Au electrode. The immobilization of antibodies at the Au electrode was carried out through a stable acyl amino ester intermediate generated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydrosuccinimide (NHS), which could condense antibodies reproducibly and densely on the self-assembled monolayer (SAM). The surface characteristics of the immunosensor before and after the binding reaction of antibodies with E. coli were characterized by atomic force microscopy (AFM). The immobilization of antibodies and the binding of E. coli cells to the electrode could increase the electro-transfer resistance, which was directly detected by electrochemical impedance spectroscopy (EIS) in the presence of Fe(CN)₆³⁻/Fe(CN)₆⁴⁻ as a redox probe. A linear relationship between the electron-transfer resistance and the logarithmic value of E. coli concentration was found in the range of E. coli cells from 3.0 × 10³ to 3.0 × 10⁷ cfu mL⁻¹ with the detection limit of 1.0 × 10³ cfu mL⁻¹. With preconcentration and pre-enrichment steps, it was possible to detect E. coli concentration as low as 50 cfu/mL in river water samples.