Used in bioconjugation chemistry, particularly in click reactions with azide-containing molecules due to the strain-promoted alkyne-azide cycloaddition (SPAAC) without requiring a copper catalyst. Its carboxylic acid group allows for easy activation and coupling to amines, making it ideal for linking biomolecules such as peptides, proteins, and antibodies. Commonly employed in the development of antibody-drug conjugates (ADCs), imaging probes, and functionalized nanoparticles. Also utilized in surface modification of materials for biosensors and diagnostic platforms. The hydrophilic spacer enhances solubility and reduces steric hindrance during conjugation.