Used in bioconjugation and labeling applications to track and visualize biomolecules in cellular and molecular studies. The maleimide (Mal) group selectively reacts with thiol groups (-SH) on proteins, peptides, or antibodies, enabling site-specific attachment. The PEG spacer improves solubility, reduces aggregation, and enhances stability of the conjugate. The FITC (fluorescein isothiocyanate) component provides green fluorescence, allowing detection and imaging using fluorescence microscopy or flow cytometry. Commonly used in developing fluorescent probes, targeted imaging agents, and diagnostic assays. Also applied in studying protein-protein interactions, receptor binding, and cellular uptake mechanisms.