Study of structural and electro-catalytic behaviour of amperometric biosensor based on chitosan/polypyrrole nanotubes-gold nanoparticles nanocomposites

In the present work a novel enzyme based biosensor has been developed by immobilizing glucose oxidase onto ITO electrode modified with biocompatible composite consisting of chitosan/polypyrrole-nanotubes and gold nanoparticles nanocomposites. Polypyrrole nanotubes and gold nanoparticles nanocomposites have been synthesized by self degradation method followed by in-situ reduction of auric chloride. The formation of PPy nanotubes and uniform decoration of Au nanoparticles over the nanotubes have been confirmed by HRTEM studies and SEM (Scanning Electron Microscopy). XRD results confirm the formation of PPy-NTs/Au-NPs nanocomposites. The enzyme electrode exhibited a well defined redox peak with formal potential (E0) of −0.45 V. The response of modified electrode showed a quasi reversible behaviour and a surface confined electrode process. A response time of less than 40 s has been found for glucose determination using the modified electrode. The bioelectrode depicted good linearity of 3-230 μM (R2 = 0.98) towards the oxidation of glucose with a sensitivity of ca. 149 μA μM−1 mL and detection limit of 3.10 μM. The calculated value of heterogeneous electron transfer rate constant (ks) was determined to be 2.54 s−1. The pH dependence of E0 suggests that the direct electron transfer of GOx was a two electron and two proton transfer reaction process.