Used in bioconjugation and drug delivery systems, it serves as a linker for attaching polyethylene glycol (PEG) chains to biomolecules, enhancing their solubility and stability. The 4-nitrophenyl carbonate group reacts efficiently with amines, making it suitable for modifying proteins, peptides, and other amine-containing compounds. Its application in PEGylation improves the pharmacokinetics and reduces immunogenicity of therapeutic agents. Commonly employed in the development of biopharmaceuticals, it aids in prolonging circulation time and improving drug efficacy.