Used extensively in biochemical research for labeling proteins, peptides, and other biomolecules. Its reactive NHS ester group enables efficient conjugation with primary amines, making it ideal for creating fluorescent probes. Commonly applied in fluorescence microscopy, flow cytometry, and cellular imaging to track and visualize molecular interactions and cellular processes. The PEG12 spacer enhances solubility and reduces steric hindrance, improving labeling efficiency and stability. Also utilized in drug delivery systems to monitor the distribution and uptake of therapeutic agents in biological systems.