Fabrication of hydrogen peroxide biosensor based on Ni doped SnO2 nanoparticles

Ni doped SnO2 nanoparticles (0-5 wt%) have been prepared by a simple microwave irradiation (2.45 GHz) method. Powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies confirmed the formation of rutile structure with space group (P-42/mnm) and nanocrystalline nature of the products with spherical morphology. Direct electrochemistry of horseradish peroxidase (HRP)/nano-SnO2 composite has been studied. The immobilized enzyme retained its bioactivity, exhibited a surface confined, reversible one-proton and one-electron transfer reaction, and had good stability, activity and a fast heterogeneous electron transfer rate. A significant enzyme loading (3.374 x 10(-10) mol cm(-2)) has been obtained on nano-Ni doped SnO2 as compared to the bare glassy carbon (GC) and nano-SnO2 modified surfaces. This HRP/nano-Ni-SnO2 film has been used for sensitive detection of H2O2 by differential pulse voltammetry (DPV), which exhibited a wider linearity range from 1.0 x 10(-7) to 3.0 x 10(-4) M (R=0.9897) with a detection limit of 43 nM. The apparent Michaelis-Menten constant (K-M(app)) of HRP on the nano-Ni-SnO2 was estimated as 0.221 mM. This excellent performance of the fabricated biosensor is attributed to large surface-to-volume ratio and Ni doping into SnO2 which facilitate the direct electron transfer between the redox enzyme and the surface of electrode. (C) 2012 Elsevier B.V. All rights reserved.