Direct Electrochemistry of Hemoglobin Based on Fe 3 O 4 @SiO 2 Nanoparticles Modified Electrode

A biosensor based on hemoglobin‐Fe 3 O 4 @SiO 2 nanoparticle bioconjunctions modified indium‐tin‐oxide (Hb/Fe 3 O 4 @SiO 2 /ITO) electrode was fabricated to determine the concentration of H 2 O 2 . UV‐vis absorption spectra, fourier transform infrared (FT‐IR) spectroscopy, cyclic voltammetry (CV) and high‐resolution transmission electron microscopy (HRTEM) were used to characterize the bioconjunction of Fe 3 O 4 @SiO 2 with Hb. Experimental results demonstrate that the immobilized Hb on the Fe 3 O 4 @SiO 2 matrix retained its native structure well. In addition, Fe 3 O 4 @SiO 2 nanoparticles (NPs) are very effective in facilitating electron transfer of the immobilized enzyme, which can be attributed to the unique nanostructure and larger surface area of the Fe 3 O 4 @SiO 2 NPs. The biosensor displayed good performance for the detection of H 2 O 2 with a wide linear range from 2.03×10 −6 to 4.05×10 −3 mol/L and a detection limit of 0.32 µmol/L. The resulting biosensor exhibited fast amperometric response, good stability, reproducibility, and selectivity to H 2 O 2 .