Fluorescent and visual assay of H2O2 and glucose based on a highly sensitive copper nanoclusters-Ce(III) fluoroprobe

Herein, we synthesized and characterized glutathione-capped copper nanoclusters (CuNCs) using a convenient one-pot chemical reduction approach based on glutathione as capping and reducing agents. The Ce(III) induced aggregation-induced emission of CuNCs to form a CuNCs-Ce3+ fluoroprobe due to electrostatic and coordination interactions between Ce3+ and CuNCs. In contrast to CuNCs, the fluorescent intensities (FLs) of CuNCs-Ce3+ were enhanced by ~ 40-fold concomitant with 20-nm blue-shift of the maximum emission, and a 3.45-fold lengthening of the average fluorescent lifetime. The FLs of CuNCs-Ce3+ were selectively quenched at 650 nm by hydrogen peroxide (H2O2) via the redox reaction. Based on this phenomenon, the sensitive assay of H2O2 was realized, and the linear range spanned over the range of 14–140 μM. Notably, the visualization of the fluorescence quenched effect of H2O2 could be easily attained. Additionally, glucose could be specifically oxidized by glucose oxidase to produce H2O2, and thus the detection of glucose was achieved according to changes in the concentrations of H2O2. Under optimized conditions, the fluorescent assay of glucose based on the CuNCs-Ce3+ system offered the linear range of 8–48 μM with detection limit of 2.4 μM. Meanwhile, high selectivity of the as-constructed fluorescent assay allows the sensitive detection of H2O2 and glucose in real-world care products and human serum samples, showing a great application potential in their conventional monitoring.