Intrinsic peroxidase-like activity of sonochemically synthesized protein copper nanoflowers and its application for the sensitive detection of glucose

We have found that protein-inorganic hybrid nanoflowers, prepared by an ultrafast sonication-mediated self-assembly of proteins and copper ions, exhibit an intrinsic peroxidase-mimicking activity, which is significantly higher than that of control materials formed in the absence of proteins. By employing glucose oxidase (GOx) as a protein component, the novel synthetic method was applied to construct GOx copper nanoflowers capable of promoting glucose-induced cascade enzymatic reactions. In the presence of target glucose, GOx, entrapped in the hybrid nanoflowers, generates H2O2 through its catalytic action; this subsequently induces peroxidase-mediated oxidation by the hybrid nanoflowers to convert the selected substrate, Amplex UltraRed (AUR), to a highly fluorescent product. Using this strategy, the target glucose was reliably determined down to 3.5 μM with high selectivity. The practical diagnostic utility of the assay system was also verified by using it to detect glucose in human blood serum. This sonochemical strategy has great potential to be extended for the construction of various oxidative enzyme-inorganic hybrid nanoflowers that are capable of detecting clinically important target molecules.