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Abstract: A simple method for polyaniline nanofibers modified glassy carbon electrode was developed. Polyaniline nanofibers (4-toluenesulfonic acid as dopant) were synthesized by interface polymerization. The polyaniline nanofibers had better processability than conventional polyaniline and were easily dispersed in chitosan solution. The mixed dispersion of polyaniline nanofibers and horseradish peroxidase was cast onto the glassy carbon electrode by a drop-coating method. The use of polyaniline nanofibers led to efficient enzyme loading and rapid electron transfer rate between the active centers of enzymes and electrodes. Horseradish peroxidase entrapped in the polyaniline nanofibers/chitosan film could keep its native bioactivity and effectively catalyze the reduction of hydrogen peroxide. The proposed biosensor exhibited good analytical performance due to the benefits of nanostructured polyaniline. This biosensor had a wide linear range of 1×10−5 to 1.5×10−3 M and correlation coefficient of 0.998 (n =17), with the detection limit of 5×10−7 M based on signal-to-noise ratio of 3. [Copyright &y& Elsevier]

Abstract: Colloidal carbon microspheres (CMS) are dispersed in chitosan (CHIT) solution to form an organic–inorganic hybrid with excellent micro-environment for the immobilization of biomolecules. A novel amperometric biosensor for the determination of hydrogen peroxide (H2O2) has been constructed by entrapping horseradish peroxidase (HRP) in as-synthesized CMS/CHIT hybrid. The modification of glassy carbon electrode is made by a simple solution-evaporation method. The electrochemical properties of the biosensor are characterized in electrochemical methods. The proposed biosensor shows high sensitive determination and fast response to H2O2 at −0.15V. The constructed HRP/CHIT/CMS/GC electrode also exhibits a fine linear correlation with H2O2 concentration. The calculated value of the apparent Michaelis–Menten constant, 2.33mM, suggests that the HRP in CMS/CHIT hybrid keeps its native bioactivity and has high affinity for H2O2. [Copyright &y& Elsevier]