TBP-based AIE Fluorescent Probe for Cysteine/Homocysteine Detection and Imaging in Living Cells

The abnormality expression of biothiols in organisms may give rise to a number of pathological conditions. Therefore, the accurate detection of biothiols is of significant importance for the diagnosis of diseases associated with their aberrant levels. In this paper, we designed a small molecule fluorescent probe with good AIE performance to specifically detect Cys/Hcy, which makes up for the limitation of probes with aggregation-induced quenching effect. The probe was synthesized by coupling 7-nitro-1,2,3-benzenediazole (NBD) as a recognition group to the fluorophore TBP, which has obvious aggregation-induced emission effect (AIE). The Cys/Hcy thiol functional group cut off the ether bond of TBP-NBD, NBD-Cys/Hcy with strong fluorescence was generated, results in a 50 ~ 100 folds increase in fluorescence intensity indicating the fluorescence was turned on. However, the fluorescence intensity was not significantly enhanced after co-incubation with GSH, which could achieve a good distinction between Cys/Hcy and GSH. In this paper, a series of experiments show that TBP-NBD has good Cys/Hcy identification ability.