Development of a two-photon fluorescent turn-on probe with far-red emission for thiophenols and its bioimaging application in living tissues

Thiophenol is a highly toxic compound which is essential in the field of organic synthesis and drug design. However, the accumulation of thiophenols in the environment may cause serious health problems for human bodies ultimately. Therefore, it is critical to develop efficient methods for visualization of thiophenol species in biological samples. In this work, an innovative two-photon fluorescent turn-on probe FR-TP with far-red emission for thiophenols based on FR-NH2 fluorophore and 2,4-dinitrophenylsulfonyl recognition site was reported. The new probe can be used for thiophenol detection with large far-red fluorescence enhancement (about 155-fold), rapid response (completed within 100 s), excellent sensitivity (DL 0.363 μM), high selectivity, and lower cellular auto-fluorescence interference. Importantly, the probe FR-TP can be successfully employed to visualize thiophenols not only in the living HeLa cells but also in living liver tissues. In addition, through two-photon tissue imaging, the probe was used to monitor and investigate biological thiophenol poisoning in the animal model of thiophenol inhalation for the first time.