Biotin-PEG3-NHS ester is widely used in bioconjugation and labeling applications due to its ability to link biotin to various biomolecules. It is particularly valuable in the preparation of biotinylated probes for use in immunoassays, such as ELISA, where it enables the detection of target molecules with high specificity and sensitivity. The NHS ester group facilitates covalent attachment to primary amines on proteins, peptides, or antibodies, while the PEG spacer enhances solubility and reduces steric hindrance. This compound is also utilized in affinity chromatography, where biotinylated molecules can be captured by streptavidin-coated surfaces for purification or analysis. Additionally, it plays a role in the development of diagnostic tools and research reagents, aiding in the study of protein interactions, cellular processes, and molecular pathways.