Rational design of metal-free fluorescent probe for tracking CO-releasing molecule-3 in vitro and in vivo

Carbon monoxide (CO), a potential therapeutic gaseous molecule for the treatment of inflammation-related diseases, is difficult to deliver directly into the body. CO-releasing molecule (CORM)− 3 is an alternative molecule for in vivo delivery of CO. To track the distribution of CORM-3 in vitro and in vivo, we reasonably designed and synthesized a series of coumarin-pyridine dyads (1−3) by DFT calculation. Applying the 4-nitrobenzyl group as the recognition site, two new metal-free fluorescent probes (MFP-1/2) were used for CORM-3 detection. As expected, probe MFP-1/2 showed an obvious off-on fluorescent response after the reaction with CORM-3. Meanwhile, probe MFP-2 exhibited good selectivity and sensitivity to CORM-3 in PBS. With the aid of its large stock shift and red emitting wavelength, MFP-2 was successfully applied to track the distribution of CORM-3 in living cells and in mice.