Used in bioconjugation and pharmaceutical research, this compound serves as a bifunctional linker that combines an aldehyde group with a carboxylic acid terminus through a hydrophilic PEG3 spacer. The aldehyde group readily reacts with primary amines to form Schiff bases, which can be reduced to stable secondary amines, enabling efficient coupling to proteins, peptides, or amine-containing molecules. The terminal carboxylic acid allows for activation and subsequent amide bond formation with nucleophiles such as amines, making it ideal for constructing complex bioconjugates like antibody-drug conjugates (ADCs) or targeted therapeutics. The PEG3 segment enhances water solubility and improves the pharmacokinetic properties of the resulting conjugates by reducing aggregation and increasing biocompatibility. Its design supports modular assembly in drug delivery systems, diagnostics, and surface functionalization of biomaterials.