NIR fluorescence imaging of lipid drops viscosity in liver organs of diabetic mice

Fluorescent labeling technology has been prevailing in the field of biotechnology, but in the more complex pathology, such as diabetes, tracking lipid droplets (LDs) viscosity remains a vacancy. To fill this gap, a new fluorescent probe (ABI-V), was herein synthesized for detecting the viscosity change of LDs in complicated biological systems. This probe displayed a larger stokes shift (195 nm), near-infrared emission and high sensitivity and selectivity to viscosity, exhibiting a 95-fold fluorescence enhancement from methanol to glycerol. In light of its distinguishable optical signals toward viscosity, the blood viscosity of diabetic mice was measured and a stronger fluorescence was obtained in the blood of diabetic mice with 2.5 times higher than normal mice. Importantly, with the assistance of ABI-V, the LDs viscosity changes in diabetic liver injury was successfully monitored at the organ and tissue levels and the results indicate that the viscosity of LDs in the liver increased under diabetic pathological conditions. Moreover, the LDs viscosity in metformin-treated diabetic liver injury was also detected accompanied by decreased fluorescence intensity comparing with the pure diabetic model, suggesting that the proposed probe ABI-V can achieve tracking the efficacy of diabetes treatment by monitoring the viscosity changes. This work provides a rewarding perspective to elucidate the role of LDs viscosity in the pathology of diabetes.