Mixed Monolayers of Ferrocenylalkanethiol and Encapsulated Horseradish Peroxidase for Sensitive and Durable Electrochemical Detection of Hydrogen Peroxide

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• 作者：Yong Peng ; Dianlu Jiang ; Lei Su ; Lin Zhang ; Ming Yan ; Juanjuan Du ; Yunfeng Lu ; You-Nian Liu ; Feimeng Zhou
• 刊名：Analytical Chemistry
• 出版年：2009
• 出版时间：December 15, 2009
• 年：2009
• 卷：81
• 期：24
• 页码：9985-9992
• 全文大小：235K
• 年卷期：v.81,no.24(December 15, 2009)
• ISSN：1520-6882

文摘

This paper describes the construction of a mixed monolayer of ferrocenylalkanethiol and encapsulated horseradish peroxidase (HRP) at a gold electrode for amperometric detection of H₂O₂ at trace levels. By tuning the alkanethiol chain lengths that tether the HRP enzyme and the ferrocenylalkanethiol (FcC₁₁SH) mediator, facile electron transfer between FcC₁₁SH and HRP can be achieved. Unlike most HRP-based electrochemical sensors, which rely on HRP-facilitated H₂O₂ reduction (to H₂O), the electrocatalytic current is resulted from an HRP-catalyzed oxidation reaction of H₂O₂ (to O₂). Upon optimizing other experimental conditions (surface coverage ratio, pH, and flow rate), the electrocatalytic reaction proceeding at the electrode was used to attain a low amperometric detection level (0.64 nM) and a dynamic range spanning over 3 orders of magnitude. Not only does the thin hydrophilic porous HRP capsule allow facile electron transfer, it also enables H₂O₂ to permeate. More significantly, the enzymatic activity of the encapsulated HRP is retained for a considerably longer period (>3 weeks) than naked HRP molecules attached to an electrode or those wired to a redox polymer thin film. By comparing to electrodes modified with denatured HRP that are subsequently encapsulated or embedded in a poly-l-lysine matrix, it is concluded that the encapsulation has significantly preserved the native structure of HRP and therefore its enzymatic activity. The electrode covered with FcC₁₁SH and encapsulated HRP is shown to be capable of rapidly and reproducibly detecting H₂O₂ present in complex sample media.