Revealing the polarity decrease of cardiomyocyte in the septic cardiomyopathy by a lipid droplets-targeting fluorescent probe with NIR emission

Septic cardiomyopathy (SCM) is the main cause of death in critically ill patients with sepsis. However, its definitive pathogenic mechanisms remain to be elucidated. Lipid droplets (LDs) are important sub-organelles that store lipids and participate in intracellular lipid metabolism. Abnormal aggregation and altered polarity of LDs are associated with the development of several cardiac diseases. To date, visualization of abnormal polarity in models of SCM has not been achieved. Herein, we designed and synthesized the probe BDP-551, a polaritysensitive probe possessing a donor-pi-acceptor (D-pi-A) structure. BDP-551 exhibits excellent photostability, high LDs targeting, near-infrared (NIR) emission (up to 678 nm) and strong polarity sensitivity. With the help of confocal imaging microscopy, the BDP-551 was able to detect the polarity changes induced in the SCM model cells and visualize the yolk sac region in hypoxic as well as inflamed living zebrafish. In addition, the BDP-551 has been successfully applied to visualize the polarity changes of mice hearts with SCM, proving a decrease of microenvironmental polarity in the development of SCM. Therefore, BDP-551 in this study can be used as a reliable tool to investigate polarity fluctuations and provide new insights into the associated pathogenic and therapeutic mechanisms on SCM.