Used extensively as a biological stain, particularly in histology and cytology, to identify and differentiate cellular components. It is effective in staining lipids and lipoproteins, making it valuable in studies of fat metabolism and storage. Additionally, it serves as a fluorescent dye in microscopy, aiding in the visualization of specific structures within cells. Its redox-sensitive properties are utilized in research to study oxidative processes in biological systems. It is also employed in photodynamic therapy research due to its light-absorbing characteristics.