A near-infrared fluorescent probe for visualizing viscosity fluxes in live cells and idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease without effective treatment that causes major health problems worldwide. Owing to the complicated mechanism and mild clinical symptoms in the early stage, many patients with IPF are often diagnosed until the late stage. Accumulating evidence indicates that abnormal changes in the viscosity are associated with many pathophysiological processes and vary with disease development. Nevertheless, the promising biological roles of viscosity in IPF have not been explored. Here, we first developed a water-soluble fluorescent probe, NIR-PF, with near-infrared emission for exploring IPF in the early stage through changes in viscosity. NIR-PF displayed the advantages of a fast response and good selectivity toward viscosity. In addition, NIR-PF exhibited great biocompatibility and has the ability to monitor fluctuations in live cells. More importantly, NIR-PF was confirmed to be sensitive enough for the visualization of IPF in the early stage in vivo, and the severity of pulmonary fibrosis had a positive correlation with the increase in viscosity. Notably, NIR-PF was successfully applied to distinguish human normal tissues from pulmonary fibrosis tissues. Therefore, NIR-PF is expected to serve as a fast and reliable tool for predicting the progression of IPF in clinical practice. • A near-infrared fluorescent probe (NIR-PF) was developed for exploring viscosity changes in different stages of IPF. • NIR-PF exhibited good biocompatibility and has the ability to monitor the fluctuation of micro-viscosity in live cells. • NIR-PF was sensitive enough for visualizing viscosity fluxes in the early stage of IPF in vivo. • NIR-PF was successfully applied to distinguish human normal tissue from the patient tissue with pulmonary fibrosis.