Polyethylene glycol: structure, properties, and biomedical applications

Polyethylene oxide, also known as polyethylene glycol (PEG), is one of the FDA-approved and commonly used golden standards as a stealth polymer in various nano-biotechnological formulations for two important reasons. The first is to prolong the circulation time, and the latter is to improve the pharmacokinetic and pharmacodynamic properties of the drug, thereby achieving enhanced therapeutic efficacy. The polymer, despite its simplicity, has found use in a variety of significant biomedical and biotechnological applications, the most prevalent of which being laxatives and active excipients in medication formulations, through a technique known as PEGylation. This could be attributed to the versatile nature of the polymer, namely, miscibility with both aqueous and organic solvents, a wide range of molecular weights, biocompatibility, biodegradability, nonimmunogenicity, easy chemical modification, etc. PEGylation has been widely reported to aid in evading the immune response and hence help in sustained drug delivery at the targeted site. So, this chapter focuses on the various physicochemical properties of PEG in detail and the recent advances in the nanomedicines/drug delivery formulations employing PEG for anticancer, transdermal delivery, and for the diseases of the cardiovascular system, gastrointestinal tract, and the central nervous system.