High efficient chromogenic catalysis of tetramethylbenzidine with horseradish peroxidase immobilized magnetic nanoparticles

Abstract The improving method of enzyme activity can be a great way to enhance the economics of biocatalytic processes. This work reported the highly efficient bio-nanocatalyst (HRP@Si-MNPs) with horseradish peroxidase (HRP) immobilization on the silica-coated magnetic nanoparticles (Si-MNPs). These bio-nanocatalysts were prepared by the reversible immobilization of silica-coated magnetic nanoparticles and HRP protein via electrostatic interactions. The binding capacity of HRP onto Si-MNPs could reach 5 ± 1.5 μg per 1 mg of Si-MNPs. Subsequently, the chromogenic decomposition of tetramethylbenzidine (TMB) was evaluated by HRP@Si-MNPs and free HRP. As a result, HRP@Si-MNPs appeared darker-blue color than that of free HRP at same substrate concentration. In addition, the apparent kinetic constant value ( V max ) of immobilized HRP was 260 μmol min −1  mg protein −1 , which was 88-folds higher than the free HRP. Therefore this approach opens new opportunities to lower manufacturing costs in large-scale industries of environment and biotechnology.