Propargyl-N-hydroxysuccinimidyl ester is widely used in bioconjugation chemistry for labeling biomolecules such as proteins, peptides, and nucleic acids. Its reactive ester group enables efficient coupling with primary amines, while the propargyl group allows for further functionalization via click chemistry, particularly copper-catalyzed azide-alkyne cycloaddition (CuAAC). This makes it a valuable tool in the development of fluorescent probes, drug delivery systems, and bioconjugate vaccines. It is also employed in the synthesis of molecular imaging agents for studying biological processes in real-time. Additionally, its application extends to surface modification of materials for biosensors and biofunctionalized scaffolds in tissue engineering.