The technique of covalently attaching polyethylene glycol (PEG) to a given molecule is known as “PEGylation” and is now a well-established method in the field of targeted drug delivery systems. PEGylation has the ability to enhance the retention time of the therapeutics like proteins, enzymes small molecular drugs, liposomes and nanoparticles by protecting them against various degrading mechanisms active inside a tissue or cell, which consequently improves their therapeutic potential. PEGylation effectively alters the pharmacokinetics (PK) of a variety of drugs and dramatically improves the pharmaceutical values; recent development of which includes fabrication of stimuli-sensitive polymers/smart polymers and polymeric micelles to cope of with the pathophysiological environment of targeted site with less toxic effects and more effectiveness. pegylation https://www.solutions.bocsci.com/pegylation.htm