Construction and application of an amperometric xanthine biosensor based on zinc oxide nanoparticles–polypyrrole composite film
2011
Devi, Rooma | Thakur, Manish | Pundir, C.S.
Zinc oxide nanoparticles (ZnO-NPs) were synthesized from zinc nitrate by simple and efficient method in aqueous media at 55°C without any requirement of calcinations step. A mixture of ZnO-NPs and pyrrole was eletropolymerized on Pt electrode to form a ZnO-NPs–polypyrrole (PPy) composite film. Xanthine oxidase (XOD) was immobilized onto this nanocomposite film through physiosorption. The ZnO-NPs/polypyrrole/Pt electrode was characterized by Fourier transform infrared (FTIR), cyclic voltammetry (CV), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS) before and after immobilization of XOD. The XOD/ZnO-NPs–PPy/Pt electrode as working electrode, Ag/AgCl as reference electrode and Pt wire as auxiliary electrode were connected through a potentiostat to construct a xanthine biosensor. The biosensor exhibited optimum response within 5s at pH 7.0, 35°C and linearity from 0.8μM to 40μM for xanthine with a detection limit 0.8μM (S/E=3). Michaelis Menten constant (Kₘ) for xanthine oxidase was 13.51μM and Iₘₐₓ 0.071μA. The biosensor measured xanthine in fish meat and lost 40% of its initial activity after its 200 uses over 100 days, when stored at 4°C.
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