A near-infrared aggregation-induced emission probe for imaging lipid droplet and in vivo visualization of diabetes-related viscosity variations

As a pivotal parameter of microenvironment, viscosity is closely related to many diseases and dysfunction in vivo. Lipid droplets, as organelles that store and metabolize lipids, are involved in various physiological processes related to metabolism in cells. Diabetes is one of the metabolic diseases that may lead to dysfunction of organs, which is associated with abnormal viscosity changes. It is of great significance for the study of related diseases to clarify the relationship between viscosity variations in vivo and monitor the changes of lipid droplets. Here, a near-infrared fluorescent probe DPX ((E)- 6-(dimethylamino)- 4-(4-(diphenylamino)benzylidene)- 9-methyl-1,2,3,4-tetrahydroxanthylium) with AIE characteristics was designed, which shows an "off-on" fluorescence response to viscosity based on twisting intramolecular charge transfer (TICT) mechanism. The probe DPX features excellent mitochondria and lipid droplets targeting, and sensitively monitor accumulation of LDs induced by oleic acid and mitochondrial viscosity variations in HeLa cells. More importantly, DPX has been successfully applied to visualize viscosity changes of diabetic liver injury in vivo, which may be benefit for development of diabetes related clinical research.