Used in bioconjugation and protein labeling, it acts as a linker to attach biomolecules like peptides or antibodies to other entities such as drugs, dyes, or nanoparticles. Its TFP ester group reacts efficiently with amines, enabling stable amide bond formation. The PEG4 spacer enhances solubility and reduces steric hindrance, making it ideal for applications in drug delivery, immunoassays, and targeted therapies. It is particularly valuable in creating antibody-drug conjugates (ADCs) for cancer treatment, ensuring precise targeting and controlled release of therapeutic agents.