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 (P42/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 (3.374×10−10 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 1.0×10−7 to 3.0×10−4 M (R=0.9897) with a detection limit of 43 nM. The apparent Michaelis–Menten constant (KMapp) 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.

► This paper presents a simple and mediator-free H2O2 detection using HRP/Ni–SnO2 bioelectrode.
► This new biosensor exhibits a wider linear range, good stability and reproducibility.
► Ni doping into SnO2 facilitates direct electron transfer between enzyme and electrode surface.
► Spherical shaped Ni–SnO2 nanoparticles was prepared by a simple microwave irradiation method.