DBCO-PEG-acid Polymer PEGylation is a technique used to modify proteins, peptides, and other molecules by attaching a polyethylene glycol (PEG) polymer to them. This process is known as PEGylation and is used to increase the size of the molecule, reduce its immunogenicity, improve its pharmacokinetic properties, and/or increase its solubility. The DBCO-PEG-acid polymer is a particular type of PEG with a dibenzocyclooctyne (DBCO) moiety at one end, which can be used to attach the PEG polymer to a target molecule through a copper-catalyzed click reaction.