Cadmium cobaltite nanosheets synthesized in basic deep eutectic solvents with oxidase-like, peroxidase-like, and catalase-like activities and application in the colorimetric assay of glucose.

Cadmium cobaltite (CdCo2O4) nanosheets were ultra-fast synthesized based on a new basic deep eutectic solvent (DES) which served simultaneously as reactant, solvents, and template. Interestingly, the nanosheets were found to exhibit triple-enzyme mimetic activities including oxidase-like activity, peroxidase-like activity, and catalase-like activity. Their catalytic activity followed the typical Michaelis-Menten kinetics, and high affinity for H2O2 and TMB was observed. Based on the superior peroxidase-like catalytic activity of CdCo2O4 nanosheets, a highly sensitive and selective colorimetric strategy for the determination of glucose was established. Under optimized conditions, the absorbance at 652 nm increases linearly in the 0.5 to 100 μM concentration range, and the limit of detection is 0.13 μM (S/N = 3). Finally, the method was successfully used for determination of glucose in serum samples. Graphical abstract The CdCo2O4 nanosheets were ultra-fast synthesized with a basic deep eutectic solvent, and this nanomaterial exhibited triple-enzyme mimetic activities: oxidase-like activity, peroxidase-like activity, and catalase-like activity. Based on the peroxidase-like activity, a highly sensitive and selective glucose colorimetric sensor was established.