Rapid detection of Escherichia coli by flow injection analysis coupled with amperometric method using an IrO₂–Pd chemically modified electrode

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• 作者：Ping Geng ; Jiaohong Zheng ; Xinai Zhang ; Qingjiang Wang ; Wen Zhang ; Litong Jin ; Zhen Feng ; Zirong Wu
• 关键词：E. coli ; Flow injection analysis ; IrO₂– ; Pd chemically modified electrode
• 刊名：Electrochemistry Communications
• 出版年：2007
• 出版时间：September 2007
• 年：2007
• 卷：9
• 期：9
• 页码：2157-2162
• 全文大小：1070 K

文摘

An amperometric method for the rapid detection of Escherichia coli (E. coli) by flow injection analysis (FIA) using an IrO₂–Pd chemically modified electrode (CME) was developed in this paper. The method is based on a good marker β-d-galactosidase which was found in E. coli strains. β-d-galactosidase was produced by the induction of isopropyl β-d-thiogalactopyranoside (IPTG) and released from E. coli cells through the permeabilization of both polymyxin B nonapeptide and lysozyme to E. coli cells wall. The released β-d-galactosidase could catalyze the hydrolysis of the substrate p-aminophenyl β-d-galactopyranoside (PAPG) in the culture medium to produce 4-aminophenol which was proportional to the concentration of E. coli. Hence, E. coli could be detected by the determination of 4-aminophenol. An IrO₂–Pd CME, which showed high sensitivity in determination of 4-aminophenol, was prepared as the electro-detector in FIA. The amplified response current of 4-aminophenol obtained at the IrO₂–Pd CME was linear with the concentration of E. coli ranging from 2.0 × 10² to 1.0 × 10⁶ cfu/mL, the detection limit of this method to E. coli was 150 cfu/mL and the complete assay could be performed in 3 h.