Novel Bis-Camphor-Derived Colorimetric and Fluorescent Probe for Rapid and Visual Detection of Cysteine and Its Versatile Applications in Food Analysis and Biological Imaging

A new colorimetric and fluorescent turn-on probe named 2,4-bis(camphor-3-methylene)phenylacrylate (BCP-Cys) was designed for highly sensitive and specific monitoring of cysteine (Cys). The probe BCP-Cys was strategically constructed by employing a new bis-camphor-derived scaffold (BCP-OH) as the fluorophore and an acrylate group as the recognition site and fluorescence quencher. The acrylate group of BCP-Cys could be exclusively cleaved by Cys and release the fluorophore BCP-OH, thereby causing a significantly enhanced red fluorescence and a naked-eye colorimetric change from colorless to yellow. The probe BCP-Cys exhibited promising sensing performances for Cys including large Stokes shift (184 nm), fast response time (<1 min), wide linear range (0-100 nM), and low detection limit (0.0728 μM). Moreover, the probe BCP-Cys could be utilized as a powerful tool for real-time determination of Cys levels within different food samples, such as onion, cabbage, broccoli, garlic, cauliflower, and bamboo sprout. In addition, this probe was also capable of imaging endogenous and exogenous Cys in living cells.