Used as a key component in lipid nanoparticle (LNP) formulations, especially in mRNA-based therapeutics and vaccines. It enhances the stability and delivery efficiency of nanoparticles by improving their circulation time in the bloodstream and reducing clearance by the immune system. The PEGylated structure helps prevent aggregation of particles and supports controlled release of the encapsulated drug or nucleic acid. Commonly found in gene delivery systems, including COVID-19 mRNA vaccines, where it contributes to the overall efficacy and pharmacokinetic profile of the formulation.