A metal organic framework obtained from cerium(III) and trimesic acid was pyrolyzed to obtain a novel nanostructure referred to as CeO2/C nanowires. The experimental parameters temperature, precursor and gas atmosphere were optimized. The nanowires show good dispersion and a large number of oxygen vacancies, and this leads to excellent peroxidase-like activity. The nanowires are stable at pH values between 2 and 10, and in the 4-80 °C temperature range. The peroxidase-mimicking activity was exploited in a sensitive colorimetric method for determination of H2O2 by using 3,3',5,5'-tetramethylbenzidine as the chromogenic substrate. The absorbance at 652 nm increases linearly in the 0.5 to 100 μM H2O2 concentration range. If glucose oxidase is added to a solution containing glucose, H2O2 will be enzymatically produced. This was exploited to design a new method for determination of glucose. The optical response is linear in the 1-100 μM glucose concentration range, and the detection limit is 0.69 μM (at S/N = 3). The method was successfully applied to the determination of glucose in serum samples. Graphical abstractCeO2/C nanowires prepared by Ce-MOF pyrolysis show peroxidase-like activity and are able to catalyze the oxidation of tetramethylbenzidine (TMB) by H2O2. This was applied to glucose oxidase-based colorimetruc determination of glucose in human sera.
Keywords: Ceria; Enzymatic assay; Hybrid nanostructures; MOF pyrolysis strategy; Nanozymes; Oxygen vacancies.