A novel colorimetric method based on copper nanoclusters with intrinsic peroxidase-like for detecting xanthine in serum samples

Abstract

A facile strategy for detecting xanthine in serum samples by copper nanocluster (CuNCs) with high intrinsic peroxidase-like activity was reported. Firstly, a simple, mild and time-saving method for preparing CuNCs was developed, in which dithiothreitol (DTT) and bovine serum albumin (BSA) were used as reductant and stabilizer, respectively. The as-prepared CuNCs exhibited a fluorescence emission at 590 nm with a quantum yield (QY) of approximately 5.29%, the fluorescence intensity of the as-prepared CuNCs exhibited no considerable change when stored under ambient condition with the lifetime is 1.75 μs. Moreover, the as-prepared CuNCs exhibited high intrinsic peroxidase-like activity with lower K _m (K _m  = 8.90 × 10⁻⁶ mol L⁻¹) for H₂O₂, which indicated that CuNCs have a higher affinity for H₂O₂. Compared with natural enzyme, the as-synthesized CuNCs are more catalytic stable over a wide range of pH (4.0~13.0) and temperature (4~80 °C). Finally, an indirect method for sensing xanthine was established because xanthine oxidase can catalyse the oxidation of xanthine to produce H₂O₂. Xanthine could be detected as low as 3.8 × 10⁻⁷ mol L⁻¹ with a linear range from 5.0 × 10⁻⁷ to 1.0 × 10⁻⁴ mol L⁻¹. These results proved that the proposed method is sensitive and accurate and could be successfully applied to the determination of xanthine in the serum sample with satisfaction.

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