A novel 2,5-bis(benzo[d]thiazol-2-yl)phenol scaffold-based ratiometric fluorescent probe for sensing cysteine in aqueous solution and serum

Abstract An efficient and novel 2,5-bis(benzo[ d ]thiazol-2-yl)phenol scaffold-based ratiometric fluorescent probe BTP-Cys for the sensing of cysteine has been developed. The probe BTP-Cys with acrylates moiety, as recognition site, has been successfully constructed on account of the excited state intramolecular proton transfer (ESIPT) mechanism. Upon the treatment with Cys (0–250 μM), this probe BTP-Cys exhibits a dramatic fluorescent intensity ratios enhancement (from 0.03 to 18.3) and a large emission shift (113 nm). The detection limit of this probe is as low as 3.8 × 10 −7  M. Importantly, the concentration and time dependent of Cys in bovine serum albumin (BSA) has also been measured, indicating that BTP-Cys could be a biocompatible and rapid probe for Cys in vitro .