111-Trifluoroethyl-PEG4-azide is widely used in bioconjugation and click chemistry applications. Its azide group enables efficient and selective reactions with alkynes through copper-catalyzed azide-alkyne cycloaddition (CuAAC), making it valuable for labeling biomolecules such as proteins, peptides, and nucleic acids. The PEG4 spacer enhances solubility and reduces steric hindrance, improving reaction efficiency in aqueous environments. This compound is particularly useful in drug delivery systems, where it facilitates the attachment of targeting moieties or therapeutic agents to carriers. Additionally, it is employed in the development of bioprobes and imaging agents for studying biological processes in vitro and in vivo. Its trifluoroethyl group provides stability and can influence the pharmacokinetic properties of conjugated molecules.