Lipid droplet-targeting fluorescence probe for imaging carbon monoxide in living cells

Lipid droplets (LDs) serve as critical organelles and play crucial roles in maintaining normal cellular functions, including energy homeostasis, autophagy regulation, and cellular homeostasis. Carbon monoxide (CO), as a gas signaling molecule, is involved in important processes such as lipid metabolism. However, due to the lack of tools that can specifically visualize the dynamic changes of CO within LDs, the potential regulatory role of CO in lipid metabolism at the subcellular level remains unclear. In this study, we rationally designed an LDs-targeting CO fluorescent probe, BTMC-CO, through strategic incorporation of an allyl-based CO-responsive moiety and morpholino group into a benzothiazole derivative. The probe demonstrated exceptional CO detection capabilities, exhibiting a rapid and remarkable fluorescence enhancement upon CO exposure. Cell experiments have shown that this probe exhibits excellent biocompatibility and significant LDs targeting ability, and were successfully applied to real-time imaging and visualization of exogenous and endogenous CO in HeLa cells. This work provides a powerful tool for exploring the role of CO in lipid droplet metabolism and related pathological and physiological processes.