Carbon dots on VO nanowires are a viable peroxidase mimic for colorimetric determination of hydrogen peroxide and glucose.

A nanocomposite was hydrothermally prepared from C-dots and VO nanowires, and characterized by TEM, FTIR and XRD. Due to the synergistic effects between C-dots and VO nanowires, the nanocomposite is found to possess peroxidase-mimicking activity. This finding was exploited to design colorimetric methods for determination of HO and glucose (via glucose oxidase) by using of 3,3',5,5'-tetramethylbenzidine (TMB) as the chromogenic substrate. The C-dot/VO nanocomposite catalyzes hydrogen peroxide to oxidize TMB and the resultant product, i.e., TMB* produces a blue color in the solution. Also for glucose determination, at first glucose reacts with dissolved oxygen in the presence of glucose oxidase and generates HO Then, produced HO was monitored by the C-dot/VO nanozyme in the presence of TMB. Intensity of the blue color in the solution at wavelength of 650 nm is an indication of HO or glucose concentration. The response to HO is linear in the 0.5-520 μM concentration ranges, and that for glucose from 0.7 μM to 300 μM. Graphical abstract Schematic presentation of peroxidase mimicking activity of C-dot/VO nanocomposite and its application as sensitive colorimetric HO/glucose assay by using of 3,3',5,5'-tetramethylbenzidine (TMB) as chromogenic substrate to induce a typical blue color reaction.