Triple-enzymatic activity of CuMn2O4 nanoparticles: Analytical applications for H2O2 and L-cysteine detection

CuMn2O4 NPs were prepared via coprecipitation method and characterized using microscopic and spectroscopic analyses. CuMn2O4 NPs exhibit a triple-enzymatic activity including peroxidase-, oxidase- and catalase-like activity. The effect of various parameters on the initial rate of the catalytic reaction of CuMn2O4 NPs with peroxidase- and oxidase-like activity was studied by UV-vis spectrometer following the increasing absorption at 415 nm corresponding to the oxidation product of substrate o-phenylenediamine (OPD). Kinetic analyses indicate the Michaelis-Menten model for CuMn2O4 NPs for both peroxidase- and oxidase-like activity. Based on the high peroxidase-like activity of CuMn2O4 NPs, they were further studied as a colorimetric sensor for the detection of H2O2 with a linear range from 0.5 mM to 22 mM and detection limit of 0.11 mM. Inhibition of the high oxidase-like activity of CuMn2O4 NPs was utilized for colorimetric detection of L-cysteine with a linear range from 50 µM to 200 µM and a detection limit of 54.15 µM.