Electrochemical properties of ferrocene modified polysiloxane/chitosan nanocomposite and its application to glucose sensor

A ferrocene functionalized polysiloxane was synthesized and its composite with chitosan was prepared. The electrochemical properties in solution and in immobilized states were examined for both the ferrocene functionalized polysiloxane and its composite with chitosan. The composite film exhibits a reversible redox wave at E-circle' = +360 mV vs. Ag/AgCl which is 110 mV more negative than that of the ferrocene functionalized polysiloxane film. It can be explained by the introduction of chitosan to enhance the hydrophilicity of the film and increase mass transport rate in aqueous condition. The composite film shows a very facile electron transport behavior with an apparent diffusion coefficient of 3.5 x 10(-6) cm(2)/s. The scanning electron microscopic analysis of the film, which is in dried state. reveals that the ferrocene polysiloxane forms average 500 nm size spheres and those are evenly distributed in the chitosan matrix to give a homogeneous nanocomposite. The significantly large value of the apparent diffusion coefficient of the ferrocene moieties in the composite film can be explained by the introduction of highly hydrophilic character to the film originated from the high water-uptake capability of chitosan to give solution-like behaviors of the film in solution. The composite is found to be a useful platform to host enzymes to make biosensors; and glucose sensing capability is demonstrated. (C) 2009 Elsevier Ltd. All rights reserved.