Novel hydrazone-based photoactivatable fluorescent probes with ultra-high photo-degradation efficiencies and their application in dynamic mitochondrial targeted bioimaging

Abstract

Photoactivatable fluorophores are useful tools in live cell bioimaging due to precise spatial and temporal control of fluorescent materials. Herein, we propose two new rhodamine 6G-derived photoactivatable fluorophores LZ1 and LZ2 with novel hydrazone caging groups that can quench the fluorescence of rhodamine 6G. Then, LZ1 and LZ2 underwent photoactivation under visible-light (530 nm) irradiation, and the post-activation forms exhibited bright fluorescence. Meanwhile, mechanism studies indicated that the hydrazone caging group was employed as a fluorescence quencher due to its photoinduced electron transfer (PET) effect. Interestingly, LZ1 and LZ2 demonstrate ultra-high photodegradation efficiencies of 95.9% and 73.3% in releasing fluorophores, respectively. Moreover, LZ1 and LZ2 can specifically locate the mitochondria in cell imaging, and their uncaging processes were clearly identified. Overall, these photocaged dyes are highly efficient, and versatile, offering promising applications in the construction of photoactivatable fluorescent probes as a new type of photocage.