A near-infrared fluorescent probe lights up protective carbon monoxide during inflammation in live systems

The role of carbon monoxide (CO) as a fundamental gasotransmitter in cellular signaling and redox homeostasis is well-established. Precise in vivo tracking of CO remains a significant challenge, as most existing fluorescent probes are limited by short emission wavelengths or small Stokes shifts, which compromise signal fidelity in deep tissues due to autofluorescence and light scattering.

To address these critical gaps, we developed DMBT-OH-CO, a near-infrared (NIR) fluorescent probe constructed on a novel dicyanoisofuranone-aminothiophenol scaffold. This rational molecular engineering achieves a synergistic combination of long-wavelength emission at 693 nm and an exceptionally large Stokes shift of 193 nm, effectively eliminating spectral crosstalk and excitation interference to ensure high-fidelity imaging. Utilizing a palladium-mediated Tsuji-Trost deallylation mechanism, the probe exhibits a rapid response, high selectivity over various biological interferents, and a competitive detection limit of 210 nM. Furthermore, DMBT-OH-CO demonstrates excellent biocompatibility and superior deep-tissue penetration. We successfully applied this tool to visualize endogenous CO upregulation in LPS-stimulated cells and, significantly, to monitor real-time, non-invasive CO fluctuations in a zebrafish inflammation model. These results validate the probe's efficacy in capturing dynamic gasotransmitter changes within complex physiological environments with high spatio-temporal resolution.

This work introduces a novel NIR imaging platform, DMBT-OH-CO, distinguished by its ultra-large Stokes shift and superior optical resolution. By overcoming the penetration limits of traditional probes, it enables the precise visualization of CO in deep tissues. Our findings provide a powerful chemical tool for elucidating the complex pathological roles of CO in inflammation, offering significant potential for future biomedical research and the diagnosis of gasotransmitter-related diseases.