Phosphatidylserine (PS) Lipid Microparticles are beads with attached phosphatidylserine. Phosphatidylserine (PS) is an anionic intracellular phospholipid component of the cell membrane and is involved in cell signaling. PS coated microparticles are intended as a positive control for apoptosis or in phagocytosis studies.Technical Notes1. Total lipid concentration is approximately 1 μmol per 1 mg particles.2. Particle comprised of a silica core and is 3 µm.