Mal-PEG6-t-butyl ester is widely used in bioconjugation and chemical biology for attaching molecules to proteins, peptides, or other biomolecules. Its PEG spacer enhances solubility and reduces steric hindrance, making it ideal for creating stable conjugates. The t-butyl ester group provides protection for carboxylic acids, which can be deprotected under mild acidic conditions for further functionalization. This compound is particularly valuable in drug delivery systems, where it helps modify therapeutic agents to improve their pharmacokinetics and targeting efficiency. Additionally, it is utilized in the development of antibody-drug conjugates (ADCs) and other biopharmaceuticals, enabling precise and controlled release of active compounds. Its versatility also extends to material science, where it aids in surface modification and functionalization of nanoparticles or polymers.