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Abstract: A homogeneous chitosan–ferrocene/graphene oxide/glucose oxidase (CS–Fc/GO/GOx) nanocomposite film was successfully constructed as a novel platform for the fabrication of glucose biosensor. The morphologies and electrochemistry of the nanocomposite film were investigated by using scanning electron microscopy and electrochemical techniques including electrochemical impedance spectroscopy and cyclic voltammetry, respectively. Results demonstrated that the uniformly dispersed GO within the CS matrix could significantly improve the stability of GO and make it exhibit a positive charge, which was more favorable for the further immobilization of biomolecules, such as GOx, with higher loading. Further attaching redox mediator ferrocene group (Fc) to CS could not only effectively prevent the leakage of Fc from the matrix and retain its electrochemical activity, but also improve the electrical conductivity of CS and promote the electron-transfer between GOx and electrode. Biosensors based on this CS–Fc/GO/GOx film had advantages of fast response, excellent reproducibility, high stability, and showed a linear response to glucose in the concentration range from 0.02 to 6.78mM with a detection limit of 7.6μM at a signal-to-noise ratio of 3 and exhibited a higher sensitivity of 10μAmM−1 cm−2. The proposed strategy based on CS–Fc/GO nanocomposite for the immobilization of enzymes can be of practical relevance for the facile design of biosensors, as well as for the construction of new multifunctional bioelectrochemical systems. [Copyright &y& Elsevier]

Abstract: A novel amperometric sensor for glucose was constructed by entrapping glucose oxidase (GOD) in a new chitosan composite doped with ferrocene monocarboxylic acid-modified 3-(aminopropyl) triethoxysilane enwrapping multiwalled carbon nanotubes (FMC-AMWNTs). The approach was very simple, timesaving and effectively prevented the leakage of the ferrocene monocarboxylic acid mediator during measurements. The entrapped FMC-AMWNTs composite performed excellent redox electrochemistry and acted as an electron transfer mediator. This matrix showed a biocompatible microenvironment for retaining the native activity of the entrapped GOD and a very low mass transport barrier to the substrate. Under optimal conditions, this biosensor was able to detect glucose in the linear range of 0.01–4.2mM with a detection limit of 3.4μM (S/N=3), the value of was 6.3mM. This immobilization approach effectively improved the stability of the electron transfer mediator and is promising for construction of biosensor and bioelectronic devices. [Copyright &y& Elsevier]