Propargyl-PEG4-N3 is widely used in bioconjugation and click chemistry applications due to its reactive azide and alkyne groups. It serves as a linker molecule in the synthesis of complex biomolecules, enabling the attachment of various functional groups or biomolecules to proteins, peptides, or other substrates. Its PEG spacer enhances solubility and reduces steric hindrance, making it ideal for drug delivery systems, targeted therapies, and the development of diagnostic probes. Additionally, it plays a significant role in the preparation of antibody-drug conjugates (ADCs) and in the modification of surfaces for biosensors or biomaterials. Its versatility makes it a valuable tool in pharmaceutical research and biotechnology.