Continuous sensing of hydrogen peroxide and glucose via quenching of the UV and visible luminescence of ZnO nanoparticles

We report on an indirect optical method for the determination of glucose via the detection of hydrogen peroxide (H2O2) that is generated during the glucose oxidase (GOx) catalyzed oxidation of glucose. It is based on the finding that the ultraviolet (similar to 374 nm) and visible (similar to 525 nm) photoluminescence of pristine zinc oxide (ZnO) nanoparticles strongly depends on the concentration of H2O2 in water solution. Photoluminescence is quenched by up to 90 % at a 100 mM level of H2O2. The sensor constructed by immobilizing GOx on ZnO nanoparticles enabled glucose to be continuously monitored in the 10 mM to 130 mM concentration range, and the limit of detection is 10 mM. This enzymatic sensing scheme is supposed to be applicable to monitoring glucose in the food, beverage and fermentation industries. It has a wide scope in that it may be extended to numerous other substrate or enzyme activity assays based on the formation of H2O2, and of assays based on the consumption of H2O2 by peroxidases.