Lipid droplet-targetable fluorescent probe for imaging viscosity in PM2.5 exposure-induced lung injury, non-alcoholic fatty liver, and tumor models

[Display omitted] •DPTP exhibits superb sensitive and selective toward viscosity.•DPTP shows great LDs targeting properties.•DPTP has ability to visualize viscosity change under different drug stimulation.•DPTP can distinguish cancer cells from normal cells.•DPTP is applied for imaging viscosity in PM2.5 exposure-induced lung injury and non-alcoholic fatty liver models. Elucidating the intrinsic relationship between viscosity and lipid droplet (LD)-related diseases remains challenging, due to the lack of sufficient attention and effective tools. So far, the visualization of abnormal LD viscosity in PM2.5 exposure-induced lung injury model, and malignant tumor tissues containing clinical cancer patient samples has not been achieved. Herein, we developed a novel LD-targetable and viscosity-sensitive fluorescent probe DPTP, based on diphenylamine-thiophene structure with multiple rotatable single bonds. DPTP displays an excellent selectivity and sensitivity toward viscosity changes in the range of 0.89–945 cP. Meanwhile, DPTP has excellent LD-targetable ability, and can monitor the increased viscosity level in the ferroptosis, inflammation, and heavy metal-induced cell injury models, respectively. Furthermore, facilitated with DPTP, we have successfully revealed a rise of LD viscosity in ambient PM2.5 exposure-induced lung injury, and non-alcoholic fatty liver (NAFL) models. Significantly, the visualization of LD viscosity has also been achieved in tumor tissues containing surgical specimens of cancer patients for the first time, making DPTP a promising tool for cancer diagnosis and imaging-guided surgery.