A novel flavonol-based fluorescent probe for rapid detection of Cysteine in food samples and its applications in bioimaging systems

L-Cysteine (Cys) plays an important role in the food industry and the physiological processes. Herein, a new fluorescent turn-on probe 6-(4-(Diphenylamino)phenyl)-2-(furan-2-yl)-3-hydroxychromone acrylate (DDPF) with AIE property based on flavonol was developed for rapidly detecting Cys. This probe displayed a significantly enhanced fluorescence response to Cys over other various competing analytes such as amino acids, cations, and anions. Probe DDPF possesses some good advantages in the detection of Cys including large Stokes shift (195 nm), low detection limit (97.6 nM), wide pH range (3-8), and fast response time (50 s). In addition, DDPF was also employed for the quantitative determination of trace Cysteine in dairy product samples, such as milk, milk powder, cheese, and yogurt. Moreover, this probe had good biocompatibility and could visualize endogenous and exogenous Cys in the living cells. Furthermore, it could be successfully applied for fluorescence imaging Cys in zebrafish.