▎ 摘　　要

In this paper, we developed a sensitive fluorescence biosensor for tyrosinase (TYR) and acid phosphatase (ACP) activity detection based on nitrogen-doped graphene quantum dots (N-GQDs). Tyrosine could be catalyzed by TYR to generate dopaquinone, which could efficiently quench the fluorescence of N-GQDs, and the degree of fluorescence quenching of N-GQDs was proportional to the concentration of TYR. In the presence of ACP, L-Ascorbic acid-2-phosphate (AAP) was hydrolyzed to generate ascorbic acid (AA), and dopaquinone was reduced to L-dopa, resulting in the fluorescence recovery of the quenched fluorescence by dopaquinone. Thus, a novel fluorescence biosensor for the detection of TYR and ACP activity based on N-GQDs was constructed. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of TYR and ACP in the range of 0.43-3.85 UmL(-1) and 0.04-0.7 mU mL(-1) with a detection limit of 0.15 UmL(-1) and 0.014 mU mL(-1), respectively. The feasibility of the proposed biosensor in real samples assay was also studied and satisfactory results were obtained. (c) 2017 Elsevier B.V. All rights reserved.