A new water-soluble two-photon fluorescent probe for detection of trace benzoyl peroxide in wheat flour and in living cell and tissue imaging

Benzoyl peroxide (BPO), a member of small-molecule reactive oxygen species (ROS), has attracted considerable attention because of its impact on human health and industrial importance. Herein, to quantitatively detect BPO in real samples and for fluorescence imaging of BPO in living cells and tissues, a new water-soluble two-photon (TP) fluorescent probe (CM-1) was constructed. Specifically, CM-1 comprises the carboxyl (-COOH) group as the water-soluble unit, cyano (-CN) group that forms the D-pi-A-structure as an acceptor to increase the two-photon action absorption cross-section and phenylboric acid (PBA) as the BPO reaction moiety. After the reaction of PBA moiety with BPO, CM-1 displayed an similar to 82-fold fluorescence intensity enhancement at 485 nm and high sensitivity with a low detection limit of 33 nM. Selectivity experiments demonstrated that the probe can detect BPO with high selectivity over other common substances, which makes it great for potential use in quantitative and simple detection of BPO in wheat flour. Moreover, CM-1 could be employed for imaging BPO in living HeLa cells and rat liver tissues with large tissue-image depth (40-150 mu m) under a two-photon excitation (800 nm), thus demonstrating its practical applications in biological systems for the study of physiological and pathological functions of BPO.