Used in bioconjugation to link biomolecules such as peptides, proteins, or antibodies with other molecules or surfaces. The maleimide group reacts selectively with thiol groups (-SH), commonly found in cysteine residues, enabling stable covalent bonding. The tri(ethylene glycol) spacer adds hydrophilicity and flexibility, reducing steric hindrance and improving solubility in aqueous environments. The terminal carboxylic acid allows further activation and coupling to amines, making it useful in constructing drug conjugates, labeling probes, or functionalizing nanoparticles and biosensors. Commonly applied in pharmaceutical development, diagnostic assays, and targeted delivery systems.