A fluorescence probe for imaging lipid droplet and visualization of diabetes-related polarity variations

Diabetes mellitus is a disorder that affects lipid metabolism. Abnormalities in the lipid droplets (LDs) can lead to disturbances in lipid metabolism, which is a significant feature of diabetic patients. Nevertheless, the correlation between diabetes and the polarity of LDs has received little attention in the scientific literature. In order to detect LDs polarity changes in diabetes illness models, we created a new fluorescence probe LD-DCM. This probe has a stable structure, high selectivity, and minimal cytotoxicity. The probe formed a typical D-π-A molecular configuration with triphenylamine (TPA) and dicyanomethylene-4H-pyran (DCM) as electron donor and acceptor parts. The LD-DCM molecule has an immense solvatochromic effect (λ_em = 544-624 nm), fluorescence enhancement of around 150 times, and a high sensitivity to polarity changes within the linear range of Δf = 0.28 to 0.32, all due to its distinctive intramolecular charge transfer effect (ICT). In addition, LD-DCM was able to monitor the accumulation of LDs and the reduction of LDs polarity in living cells when stimulated by oleic acid, lipopolysaccharide, and high glucose. More importantly, LD-DCM has also been used effectively to detect polarity differences in organs from diabetic, drug-treated, and normal mice. The results showed that the liver polarity of diabetic mice was lower than that of normal mice, while the liver polarity of drug-treated mice was higher than that of diabetic mice. We believe that LD-DCM has the potential to serve as an efficient instrument for the diagnosis of disorders that are associated with the polarity of LDs.