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.