Plasma membranes are critical to the proper function and viability of cells. They act as selective barriers protecting the cells from their environment as well as solvent for various proteins that play a major role in cell signaling. The structure of the cell membrane plays an important part in both these roles. The structure of plasma membranes has been subject of intense research because of its importance in various fields such as pharmaceutical manufacturing, disease conditions, drug delivery and gene therapy.

Using cells for manufacturing and research purposes has become a day-to-day event, but structure of plasma membrane is not well understood. We need a better understanding of: 1) Breaching the plasma membrane as in the case of gene therapy where the gene is to be delivered into the cell past the membrane or in chemotherapy, when the cells become resistant to the drugs by developing a rigid plasma membrane, 2) the role of the membrane protecting the cell membrane when handling or pumping the cells during drug manufacture. Given the dimensions of cells and their membranes, microscopic interactions play a very important role in determining the membrane structure. The localized atomic level information given by molecular simulations will be very important in understanding the behavior of cell membrane lipids under various conditions.

We use Molecular Dynamics to compute the atomic structure and dynamics of a lipid bilayer system from known atomic interactions. Our goal is to use an all atom molecular dynamics simulation, of phospholipid bilayer representing the plasma membrane and to investigate the interactions between these lipids at the atomic level. Various properties such as order parameters, correlation functions and the radial distribution function were determined. These properties were used to investigate changes in the structure and fluidity of the plasma membrane as a function of composition.