Visualizing lysosomal viscosity in atherosclerosis with a long-wavelength and large Stokes shift fluorescent probe

We developed a viscosity-activated near-infrared (NIR) fluorescent probe, QV-S. This probe features a long emission wavelength (815 nm), a large Stokes shift (135 nm), high viscosity sensitivity (431-fold signal enhancement), and specific lysosome-targeting capability. QV-S allows for not only real-time monitoring of lysosomal viscosity changes in inflammatory and foam cells but also the precise imaging of atherosclerotic plaques in the aortas of ApoE^-/- mice.