Ultra-fast zinc ion detection in living cells and zebrafish by a light-up fluorescent probe

As the second most abundant transition metal after iron in biological systems, Zn 2+ takes part in various fundamental life processes such as cellular metabolism and apoptosis, neurotransmission. Thus, the development of analytical methods for fast detection of Zn 2+ in biology and medicine has been attracting much attention but still remains a huge challenge. In this report, we develop a novel Zn 2+ -specific light-up fluorescent probe based on intramolecular charge transfer combined with chelation enhanced fluorescence induced by structural transformation. Addition of Zn 2+ in vitro can induce a remarkable color change from colorless to green and a strong fluorescence enhancement with a red shift of 43 nm. Moreover, the probe shows an extremely low detection limit of 13 nM and ultra-fast response time of less than 1 s. The Zn 2+ sensing mechanism was fully supported by TDDFT calculations as well as HRMS and 1 H NMR titrations . The recognition of Zn 2+ in living Hela cells as well as the MTT assay demonstrate that the probe can rapidly light-up detect Zn 2+ in vivo with low cytotoxicity and good cell-permeability. Furthermore, the probe can also be successfully applied to bioimaging Zn 2+ in living zebrafish.