Fe/C magnetic nanocubes with enhanced peroxidase mimetic activity for colorimetric determination of hydrogen peroxide and glucose

Iron-carbon (Fe/C) magnetic nanocubes were synthesized by direct pyrolysis of Prussian blue nanocubes under an inert gas atmosphere. They are shown to possess intrinsic peroxidase mimicking activity to catalyze the oxidation of peroxidase substrate N,N-diethyl-p-phenylenediamine sulfate salt to form a purple colored product in the presence of H2O2. The values for K-m and V-max are 74M and 46nmols(-1), respectively. Steady-state kinetic analysis also indicates that the catalysis reaction follows a ping-pong mechanism. Based on these findings, an ultrasensitive colorimetric H2O2 assay was worked. Absorbance (best value measured at 550nm) increases linearly in the 10nM to 0.2mM H2O2 concentration range, and the limit of detection is 1.5nM. The method was also applied to the quantification of glucose, which is oxidized by glucose oxidase in the coexistence of H2O2. The response covers the 0.1 to 500M glucose concentration range, and the limit of detection is 16nM. The method was applied to the determination of H2O2 in rainwater samples. The glucose assay was used to analyze serum samples, and satisfactory results were obtained.Other attractive features include good chemical activity, low cost, easy storage, and high catalytic efficiency.