PEGylation is a process of attaching one or more molecules of polyethylene glycol (PEG) to target biomolecules including peptides, proteins and oligonucleotide. It is a vital modification used in biopharmaceuticals to facilitate the functions of therapeutic proteins and peptides. PEGylation improves pharmacokinetic and pharmacodynamic properties of proteins and enable to attain maximum clinical potency. PEG has been approved as pharmaceutical excipient for injection by FDA.