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

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 beta-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 mmol L-1 and 12.619 mmol 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.