An ultrasensitive lipid droplet-targeted NIR emission fluorescent probe for polarity detection and its application in liver disease diagnosis

Compared to normal cells, cancer cells require more energy supply during proliferation and metabolism. In living cells, in addition to mitochondria, lipid droplets are also an important organelle for providing energy. Studies have shown that the number and distribution of lipid droplets change significantly during the production of lesions in cells. At this stage, the predisposing factors for the development of cellular lesions are not clear, thus leading to limitations in the early diagnosis and treatment of diseases such as liver injury, fatty liver, and hepatitis. To meet the urgent challenge, we used a near-infrared emission fluorescent probe SSR-LDs based on the intramolecular charge transfer effect (ICT) to detect polarity changes within intracellular lipid droplets. The probe SSR-LDs has ultra-sensitive polarity sensitivity, excellent chemical stability and photo-stability. In addition, by comparing normal and cancer cells through cell imaging experiments, we found that the robust probe has the ability to sensitively monitor the changes in lipid droplet polarity in the living cells. More importantly, using the constructed fluorescent probe, we have achieved an in vitro fluorescence detection of liver injury and fatty liver, and the detection of hepatitis at the in vivo level. The unique fluorescent probe SSR-LDs is expected to serve as a powerful tool for the medical diagnosis of diseases related to lipid droplet polarity.