Tos-PEG-t-butyl ester contains a tosylate (Tos) functional group (-OTs) attached to one end of a PEG chain and a t-butyl ester (-COO-tBu) group at the other end. The Tos group is a leaving group that can be easily replaced by other nucleophiles, while the t-butyl ester group provides steric hindrance and protects the PEG chain from hydrolysis.
Tos-PEG-t-butyl ester has been widely utilized in the field of pharmaceutical research and development for its ability to functionalize biomolecules, such as proteins and peptides, with PEG chains. The Tos group can be easily replaced with various nucleophiles, such as amines or thiols, resulting in the covalent attachment of PEG chains to the biomolecules. The resulting conjugates exhibit improved stability, increased solubility, and reduced immunogenicity, making them promising candidates for drug delivery and therapeutic applications.
Moreover, the t-butyl ester group of Tos-PEG-t-butyl ester can be easily removed under mild conditions, such as acidic or enzymatic hydrolysis, to generate the corresponding hydroxyl (–OH) group. This allows for the site-specific introduction of functional groups, such as carboxylic acids or amines, onto the PEG chain, which can be further utilized for conjugation with other molecules or for surface modification of biomedical devices.