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Issue 4, 2004
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Functional lipid microstructures immobilized on a gold electrode for voltammetric biosensing of cholera toxin

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Abstract

Redox functionalized microstructures of diacetylene lipids containing cell surface ligand GM1 have been prepared for the construction of an electrochemical biosensor for cholera toxin from Vibrio cholerae. Incorporation of lipid molecules with disulfide functionality into the microstructures allows for firm attachment of the microstructures on a gold surface to form a sensing interface. The observed morphology of the microstructures is platelet, with size around 240 nm as determined by dynamic light scattering and transmission electron microscopy. The electrochemical response stems from electron transfer between the electrode and the redox sites on the microstructures, and the Faradaic current is influenced by the binding events of protein toxins to the ligands displayed on the crystalline surface. Electrochemical characterization indicates that electron transfer of surface ferrocene on the gold electrode is facile. Differential pulse voltammetry was used to measure the current magnitude as a function of toxin concentration, and a working range expanding from 1.0 × 10−8 to 5.0 × 10−7 M was obtained. Bovine serum albumin (BSA) was used as a control agent with which no interference to Faradaic response was found in the same concentration range. Atomic force microscopy (AFM) was used to characterize the morphology and distribution of microstructures on the gold surface. The effectiveness of the design for bypassing surface fouling of proteins in electrochemical detection has been demonstrated, and a binding regulated electron hopping mechanism for the observed electrochemical behavior has been proposed.

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Publication details

The article was received on 03 Dec 2003, accepted on 16 Feb 2004 and first published on 15 Mar 2004


Article type: Paper
DOI: 10.1039/B315656G
Analyst, 2004,129, 309-314

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    Functional lipid microstructures immobilized on a gold electrode for voltammetric biosensing of cholera toxin

    Q. Cheng, S. Zhu, J. Song and N. Zhang, Analyst, 2004, 129, 309
    DOI: 10.1039/B315656G

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