Quantum dots mediated fluorescent "turn-off-on" sensor for highly sensitive and selective sensing of protein

We described a highly sensitive and selective strategy for sensing of human serum albumin (HSA) by constructing a reversible fluorescent "turn-off-on" sensor. Monodispersed cadmium telluride quantum dots (CdTe QDs) were synthesized by using a simple aqueous phase synthesis method, which exhibited strong green fluorescence. The CdTe QDs fluorescence was first quenched using resveratrol through dynamic quenching type, that is to say, excited states CdTe QDs collided with resveratrol. HSA can cooperate with resveratrol to dissociate CdTe QDs/resveratrol, leading to the recovered fluorescence of CdTe QDs. Therefore, a facile reversible fluorescent "turn-off-on" sensor can be developed for HSA detection. In a wide concentration range of HSA (0.0237-100 μg mL^-1), the detection limit could reach 6.898 ng mL^-1, which was much lower than previously reported values, indicating high sensitivity. Meanwhile, this strategy was successfully applied to the synthetic samples and demonstrated ideal selectivity. Moreover, the mechanisms of the interactions among QDs, resveratrol, and HSA were also investigated. The proposed strategy for HSA determination based on the constructed reversible fluorescent "turn-off-on" sensor suggests great promising in fluorescent sensing.