A metal-free coumarin-based fluorescent probe for turn on monitoring carbon monoxide in aqueous solution and living cells

Endogenous carbon monoxide (CO) is an essential cell signaling molecule, which is closely related to many physiological and pathological processes. So it is of great significance to monitor CO in living samples. Fluorescent probe technique provides an effective and convenient method for the monitor of CO. Although many fluorescent probes of CO have been reported, most of them require the introduction of heavy metal ions (Pd2+), which is not conducive to the practical application of these probes. Herein, a metal-free coumarin-based fluorescent probe for monitoring CO was developed. For this probe, the coumarin was selected as fluorophore, aromatic nitro was used as reactive site, and carboxyl moiety was acted as water-soluble unit. As a result, this probe has been proved to be able to monitor CO with good specificity and excellent sensitivity in water medium. After interaction with CO, the aromatic group was reduced to aryl amino group, accordingly, the emission intensity located in 450 nm of the probe significantly increased. Moreover, it successfully realized the detection of CO in living cells by fluorescence signal.