A turn on fluorescent probe based on carbon dots–MnO2 nanosheets for determination of uric acid

Uric acid is a product of the metabolic decomposition of purine nucleotides, and it is a normal component of urine. Numerous illnesses, biochemical changes or physiological disorders are depended on the uric acid concentration. Thus, it is important to design simple and sensitive methods to sense uric acid concentration in biological fluids. In this study, a turn on fluorescent probe, based on the interaction of carbon dots–MnO2 nanosheets, was developed for monitoring of uric acid(1,2). MnO2 nanosheets are two-dimensional nanomaterials which have attracted tremendous attention due to their unique photophysical property, high colloidal stability, good biocompatibility and rich redox chemistry. Recently, they have been applied as quencher in fluorescent probes(3). One of the novel classes of highly luminescent nanomaterials which have inspired great attention in various fields is carbon dots(4). We found that the fluorescence intensity of carbon dots was efficiently quenched in the presence of MnO2 nanosheets due to the formation of carbon dots–MnO2 nanocomposites. It was also observed that the fluorescence of carbon dots was recovered by adding uric acid to the solution of carbon dots–MnO2 nanosheets. Under optimum conditions, the enhanced fluorescence intensity displayed a linear relationship with the concentration of uric acid in the range of 2.5-30 μM with a detection limit of 0.8μM. The developed method was applied to the determination of uric acid in biological samples with satisfactory results.