Molecular Dynamics Simulation Study of Pulmonary Surfactant Interacting With Nanoparticles

Dipalmitoylphospatidylcholine (DPPC) a phospholipid, is the main component of the lung pulmonary surfactant. Components of pulmonary surfactant including dipalmitoylphosphatidic acid (DPPA), dipalmitoylphosphatidyl ethanolamine (DPPE), dimyristoylphospatidylcholine (DMPC) and possibly lung pulmonary surfactant proteins are expected to play a significant role in the biological mechanism of defense against quartz cytotoxicity. Interactions of powder crystalline silica with biological systems cause cell damage, inflammation, and apoptosis. Unfortunately, mechanisms involved in these diseases are still unknown. Currently, molecular dynamics (MD) simulation of phospholipid bilayer are widely used to study the physicochemical properties of pure bilayers, composite bilayers, lipid rafts, cellular processes such as signaling and transport, permeation of water. Silica dust particles in the form of quartz (but not kaolin) have been hypothesized to promote pulmonary diseases such as silicosis. An exact mechanism of silica cytotoxicity at the molecular level is still unknown. It is known that silanol groups on crystalline silica are lethal while amorphous silica and silica in phyllosilicates (e.g., kaolinite) cause virtually no long-term adverse effects. Our 5ns MD simulation studies using NAMD of lipid bilayers supported on alpha-quartz (nanoparticles) and kaolinite with explicit water molecules will be presented to understand the physiochemical effects of nanoparticles on pulmonary surfactant.