DiR is widely used as a fluorescent dye in biological imaging due to its near-infrared emission properties, making it ideal for deep tissue imaging. It is particularly useful in vivo for tracking cells, visualizing tumors, and studying vascular systems, as it minimizes interference from autofluorescence and light scattering. DiR is also employed in labeling liposomes and nanoparticles for drug delivery research, enabling real-time monitoring of their distribution and accumulation in target tissues. Its lipophilic nature allows it to integrate into cell membranes, making it a valuable tool for studying cell migration and membrane dynamics. Additionally, DiR is used in preclinical studies to assess the efficacy of therapeutic agents and to evaluate biodistribution patterns in animal models.