A highly effective curcumin-based fluorescent probe with single-wavelength excitation for simultaneous detection and bioimaging of Cys, Hcy and GSH.

Cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) act as significant roles in many physiological processes, and their abnormal proliferation will cause multiple diseases including Alzheimer's disease, Parkinson's disease, Cardiovascular disease, atherosclerosis, and soft tissue damage. However, It is challenging work to develop a efficient method for differentiating and detecting GSH, Cys and Hcy because of their significant similarity in structures and functions. In this work, a smart fluorescent probe FBCN based on curcumin was rationally devised and developed by etherifying the phenol hydroxyl group on FBC with NBD-Cl, which emitted strong green at 516 nm. FBCN distinguished Hcy from Cys/GSH with naked eyes based on the color variation of probe solution in sunlight. Meanwhile, GSH induced the powerful fluorescence quenching of probe solution, but the fluorescence color of FBCN solution transformed from green to luminous yellow accompanied with emission wavelength redshifted from 516 nm to 540 nm or 553 nm in the existence of Hcy and Cys, respectively. Probe FBCN had outstanding sensitivity and anti-interference, low detection limit (56.5 nM, 77.7 nM, and 288 nM corresponded to Cys, Hcy, and GSH, respectively), short response time (the response time of FBCN to Cys, Hcy and GSH was 1 min, 2 min and 5 min, respectively). The DFT calculation and HRMS had verified the sensing mechanism of FBCN to biothiols. In addition, the probe was successfully utilized to detect three biothiols levels in living cell and zebrafish.