Used as a key component in lipid nanoparticles (LNPs) for drug delivery, particularly in mRNA-based vaccines and therapies. Its PEGylated structure enhances nanoparticle stability in the bloodstream by reducing aggregation and minimizing clearance by the immune system. The polyethylene glycol (PEG) chain provides a hydrophilic shield around the lipid nanoparticle, prolonging circulation time and improving targeted delivery to cells. Commonly employed in pharmaceutical formulations where controlled release and improved bioavailability are critical. Also helps modulate the size and physical properties of LNPs during formulation.