DBCO-PEG4-acid is widely used in bioconjugation and click chemistry applications due to its reactive DBCO (dibenzocyclooctyne) group and hydrophilic PEG (polyethylene glycol) spacer. It is particularly valuable in labeling biomolecules such as proteins, antibodies, and peptides, where the DBCO group allows for efficient, catalyst-free reactions with azide-containing compounds. The PEG4 spacer enhances solubility and reduces steric hindrance, improving the efficiency of the conjugation process. This compound is also employed in the development of drug delivery systems, where it facilitates the attachment of targeting ligands to therapeutic agents. Additionally, it is utilized in the preparation of biofunctionalized surfaces for diagnostic assays and biosensors, enabling precise and stable immobilization of biomolecules. Its versatility makes it a key tool in chemical biology and materials science.