An activatable fluorescent probe for targeting cellular membrane through the biothiol-mediated hydrazone-to-pyrazole transformation

A non-fluorescent coumarin-hydrazone conjugate probe was transformed into a strongly fluorescent pyrazolyl coumarin through a thiol-mediated cyclization reaction with F/F0 50. Interestingly, the probe was initially expressed at the cellular cytoplasm but translocated into the membrane regions of cells upon reaction with cellular enriched glutathione, which allowed us to obtain clear membrane imaging in the living cells.