Figure 5.

The Building Blocks of a PEGylated Therapeutic. Once a therapeutic molecule amenable to PEGylation is identified, the appropriate PEG chemistry must be selected. Properties such as size, symmetry, and bifunctionality must be considered and adopted according to the desired application. The linker used for covalent attachment of PEG must also be evaluated with respect to the strength of the bond created as well as its affinity for certain residues on the bioactive molecule. Receptor-specific peptides, proteins and molecular sensors have been tethered to PEGylated therapeutics for cellular and tissue specific targeting.