ZnO-Associated Carbon Dot-Based Fluorescent Assay for Sensitive and Selective Dopamine Detection

This paper presents a simple and highly efficient method for dopamine detection using water-soluble carbon dot nanoparticles. The ZnO-associated carbon dots (CDZs) were synthesized using a green chemical strategy. An examination of the effects of biomolecules on the fluorescence of CDZs revealed selective dopamine-induced quenching. In a phosphate buffer (pH = 7.4) medium, a detection limit of 1.06 nM was obtained. This "turn off" phenomenon was attributed to the electronic interaction between CDZs and dopamine, during the oxidation of dopamine. At lower pH, however, the effects of dopamine on the fluorescence of CDZs were insignificant as the oxidation of dopamine was hindered when the proton concentration was increased. This method was found to be free from the interference of coexisting molecules, that is, ascorbic acid and uric acid. This sensing platform was applied successfully in biological fluids to confirm the practical significance of the as-designed sensor.