Used in bioconjugation processes to link biomolecules, such as proteins or peptides, with other entities like drugs or fluorescent markers. The maleimide group reacts specifically with thiol groups, enabling precise attachment, while the PEG spacer enhances solubility and reduces immunogenicity. The t-butyl ester group provides protection during synthesis and can be removed under specific conditions to reveal a reactive carboxyl group. This makes it valuable in drug delivery systems, diagnostic assays, and targeted therapies, where controlled and stable conjugation is essential.