Facile preparation of arginine-based carbon dots for highly selective detection of dopamine

Arginine-based carbon dots (Arg-CDs) were synthesized through a facile one-step hydrothermal method using arginine and urea as precursors. The as-prepared Arg-CDs displayed good aqueous solubility and typical excitation-dependent emission property, with the fluorescence quantum yield of 25.47 %. The fluorescence of Arg-CDs was gradually quenched by the addition of dopamine (DA) in the alkaline solution. However, under neutral and acidic condition, the fluorescence intensity of Arg-CDs remained unchanged upon the addition of DA. The sensing mechanism was probably due to the rapid oxidation of DA to dopaquinone in alkaline condition, which could quench the fluorescence of Arg-CDs through the Inner Filter Effect (IFE). Moreover, the fluorescence change of Arg-CDs was proportional to the concentration of DA under the optimized condition. Because of the linear relationship, the detection limit of dopamine was calculated to be 0.28 mu M with the detection range from 10 to 100 mu M. The interference experiment was carried out to further verify the specificity of this fluorometric method. Finally, the fluorometry based on Arg-CDs has been successfully used to the determination of DA in human serum with high accuracy and satisfactory recovery.