A simple and convenient fluorescent strategy for the highly sensitive detection of dopamine and ascorbic acid based on graphene quantum dots

In this paper, a simple and convenient fluorescent turn off-on strategy for the highly sensitive detection of dopamine (DA) and ascorbic acid (AA) based on graphene quantum dots (GQDs) was developed. DA and GQDs can form the DA-GQDs complex due to the electrostatic interaction and hydrogen bonding. The interaction between Cu2+ and the catechol moiety of DA-GQDs complex could lead to strong fluorescence quenching of GQDs. When AA is introduced into the system, AA can reduce Cu2+ to Cu+, disturbing the interaction between Cu2+ and DA-GQDs complex and resulting in the fluorescence recovery of GQDs. Thus, a sensitive and convenient sensor for the detection of DA and AA was developed. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of DA and AA in the range of 0.5-120 mu mol L-1 and 0.05-6 mu mol L-1 with a detection limit of 0.16 mu mol L-1 and 0.021 mu mol L-1, respectively. Meanwhile, the proposed method has potential applications on the detection of DA and AA in human urine and serum samples.