The screening of metal ion inhibitors for glucose oxidase based on the peroxidase-like activity of nano-Fe3O4

Abstract

In this study, a colorimetric method is proposed based on the peroxidase-like activity of Fe₃O₄ magnetic nanoparticles for screening metal ion inhibitors for glucose oxidase activity. First, the glucose oxidase was typically used as a specific enzyme to catalyze the oxidation of β-D-glucose resulting in the generation of hydrogen peroxide. Next, having an inherent peroxidase-like activity, Fe₃O₄ magnetic nanoparticles were adopted as the catalyst. Then, the generated H₂O₂ was capable of participating in the oxidation of 3,3′,5,5′-tetramethylbenzidine to yield a blue colored product. Based on the above results, an in vitro screen model of metal ion inhibitors of glucose oxidase was thus established. Metal ions including Ca²⁺, Pb²⁺, Mn²⁺, Ag⁺, Al³⁺, Cu²⁺, Mg²⁺ and Zn²⁺ have been tested. Herein, towards the glucose oxidase activity, Ca²⁺, Pb²⁺, Mg²⁺ and Mn²⁺ showed no effect while Al³⁺ and Zn²⁺ displayed a slight activation, while of Ag⁺ and Cu²⁺ expressed a strong inhibition. The further detection of Ag⁺ and Cu²⁺ manifested that their IC₅₀ were 0.662 μmol L⁻¹ and 12.619 μmol L⁻¹, respectively. The entire detection process could be accomplished within 15 min. This assay is economical, time-saving and highly-effective with definitely significant reference for the screening of metal ions as glucose oxidase inhibitors.