Used as a near-infrared fluorescent dye in biological imaging and labeling applications. Its strong absorption and emission in the NIR region make it suitable for deep tissue imaging with minimal autofluorescence and light scattering. Commonly employed in fluorescence microscopy and in vivo imaging for tracking cells, proteins, and other biomolecules. Also utilized in photodynamic therapy and as a photosensitizer in diagnostic applications due to its photostability and high quantum yield.