Hydroxy-PEG6-t-butyl ester is widely used in bioconjugation and drug delivery systems due to its ability to enhance solubility and stability of therapeutic compounds. It serves as a linker in the synthesis of antibody-drug conjugates (ADCs), enabling the attachment of cytotoxic agents to antibodies for targeted cancer therapy. Additionally, it is employed in the modification of peptides and proteins to improve their pharmacokinetic properties, such as prolonged circulation time and reduced immunogenicity. The t-butyl ester group provides a protective functionality, which can be selectively removed under specific conditions, allowing for controlled release of active molecules. This compound is also utilized in the development of hydrogels and biomaterials for tissue engineering, where its PEG moiety contributes to biocompatibility and hydration.