DiR' [DiIC18(7)] is widely used as a near-infrared fluorescent dye for labeling and tracking cells, lipids, and nanoparticles in biomedical research. Its deep tissue penetration and minimal background interference make it ideal for in vivo imaging applications, such as monitoring tumor progression, studying cell migration, and visualizing vascular structures. It is also employed in drug delivery studies to trace the distribution and uptake of liposomes or other carriers in animal models. Additionally, DiR' is utilized in flow cytometry and microscopy to analyze cell populations and membrane dynamics due to its strong fluorescence and stability.