High performance nanozymatic assay-based CuO nanocluster supported by reduced graphene oxide for determination of hydrogen peroxide and ascorbic acid

Abstract Several efforts have been made to increase the nanozymatic activity of reduced Graphene Oxide (rGO). Also, the enzyme mimetic research with Nanoclusters (NCs) is in the embryo stage. For the first time, a one pot synthesis method was used successfully for preparation of CuONCs loaded r-GO (CuONCs/rGO). GO and copper sulfate were used as precursors and Bovine Serum Albumin (BSA) as the reducer and stabilizer agent. This nanocomposite possesses intrinsic peroxidase-like activity, which can catalyze the oxidation of 3,3’,5,5’-tetramethylbenzidine substrate (TMB) by H2O2 to produce an intense blue color in the system. The color change was monitored by absorbance at 650 nm using a UV-vis spectrophotometer. The higher value of Vmax reflected the higher catalytic activity of CuONCs/rGO compared to other similar nanozymes. The increase in the blue color intensity was proportional to the H2O2 concentration in the range of 3.03 × 10-7-5.7 × 10-4 M with a detection limit of 3.03 × 10-7 M. Furthermore, Ascorbic Acid (AA) could reduce the intensity of the blue color in this system. Therefore, AA was determined within the range of 3.0 × 10-7-3.8 × 10-5 M at the detection limit of 3.0 × 10-7 M. The satisfactory results were due to the synergic effect of CuONCs and rGO in the nanocomposite.