▎ 摘 要
A novel fluorescent sensing platform based on nitrogen-doped graphene quantum dots (N-GQDs) is presented, which is able to detect various metabolites (cholesterol, glucose, lactate, and xanthine) rapidly, sensitively, and selectively. Hg(2+)can attach on the surface of N-GQDs, leading to the quenching of N-GQD fluorescence. In the presence of cysteine (Cys), Hg2+ is released from N-GQDs and associates with Cys. Then, the fluorescence of N-GQDs is recovered. Hydrogen peroxide, resulting from the enzymatic oxidation of metabolites, can convert two molecules of Cys into one molecule of cystine, which cannot bind with Hg2+. So, the fluorescence of N-GQDs quenched again. For cholesterol, glucose, lactate, and xanthine, the limits of detection are 0.035 mu mol/L, 0.025 mu mol/L, 0.07 mu mol/L, and 0.04 mu mol/L, respectively, and the linear ranges are 1-12 mu mol/L, 0.06-3 mu mol/L, 0.2-70 mu mol/L, and 0.12-17 mu mol/L, respectively. The presented method was applied to quantify metabolites in human blood samples with satisfactory results.