Used as a key component in lipid-based drug delivery systems, particularly in the formulation of liposomes and lipid nanoparticles (LNPs). Its negatively charged head group helps stabilize nanoparticle structure and influences cellular uptake. Commonly employed in mRNA vaccines and cancer therapies to enhance delivery efficiency and protect nucleic acids from degradation. Also serves as a matrix lipid in studies of membrane biophysics due to its well-defined phase behavior and ability to form stable bilayers.