Used in bioconjugation to attach biotin to thiol-containing molecules such as cysteine residues in proteins or thiol-modified nucleic acids. The maleimide group reacts selectively with sulfhydryl groups under mild conditions, forming a stable thioether bond. This allows for specific labeling, detection, or immobilization of biomolecules in applications like ELISA, Western blotting, flow cytometry, and affinity purification. Biotin-maleimide is particularly useful in pull-down assays and protein interaction studies where streptavidin-based detection systems are employed. It is also applied in the development of biosensors and targeted drug delivery systems due to its strong and specific interaction with streptavidin or avidin.