Fluorescent TICT Probe for Precise Monitoring of Cellular Lipid Droplets.

Lipid droplets (LD) are crucial in pathological processes or conditions associated with abnormal lipid metabolism, such as obesity, diabetes, atherosclerosis, fatty liver diseases, and cancers. Cancer cells frequently contain elevated levels of nonpolar lipid droplets (LDs), serving as energy reserves. The proliferation of LDs, accompanied by an increase in viscosity, is a characteristic feature of cancer cells that prompted us to devise a fluorescent sensor for LD detection at physiological pH. However, developing fluorescent LD-specific probes with high polarity sensitivity and deep tissue/cell imaging capability remains challenging. Therefore, we present a TICT probe with strong solvatochromism, superior response to viscosity, microenvironment sensitivity, and a large Stokes shift. Additionally, it offers numerous advantages, including high sensitivity, specificity, high fluorescence quantum yield, and remarkable spatial resolution, which enables precise monitoring of lipid droplets (LD). Thus, this probe can effectively monitor alterations in viscosity and polarity of lipid droplet expression in live cells, thereby offering the potential for visualizing physiological abnormalities or pathological conditions. The probe offers excellent lipid droplet targeting and also sensitively monitors the oleic-acid-mediated lipid droplet accumulation and immunosuppressant/inflammatory drugs in HeLa cells.