A MgO Nanoparticles Composite Matrix-Based Electrochemical Biosensor for Hydrogen Peroxide with High Sensitivity

A novel horseradish peroxidase (HRP) electrochemical biosensor based on a MgO nanoparticles (nano-MgO)-chitosan (chit) composite matrix was developed. The morphology of nano-MgO-chit nanocomposite was examined by scanning electron microscopy (SEM). The interaction between nano-MgO-chit nanocomposite matrix and enzyme was characterized with UV-vis spectra. This proposed composite material combined the advantages of inorganic nanoparticles and organic polymer chit. The HRP immobilized in the nanocomposite matrix displayed excellent electrocatalytic activity to the reduction of H2O2 in the presence of hydroquinone as a mediator. The effects of the experimental variables such as solution pH and the working potential were investigated using steady-state amperometry. The present biosensor (HRP-modified electrode) had a fast response towards H2O2 (less than 10 s), and excellent linear relationships were obtained in the concentration range of 0.1–1300 μM, with a detection limit of 0.05 μM (S/N=3). Moreover, the stability and reproducibility of this biosensor were evaluated with satisfactory results.