Molecular Dynamics Simulation of Lipid Bilalyer Consisting of DPPC and Mppc: Effect of Configuration

Liposomes, spherical nanoparticles composed of phospholipid bilayers, have been suggested as a drug delivery system to transport chemotherapeutics. Through the transition of lipid bilayer from gel to liquid-crystalline, the structure reaches its maximum permeability and thereby the encapsulated drugs are released. Incorporating both Dipalmitoyl Phosphatidyl Choline (DPPC) and a mono-tailed lysolipid (MonoPalmitoyl Phoshatidyl Choline, MPPC)—the transition temperature could be targeted at the temperature of mild hyperthermia. There have been studies that looked at the different percent compositions of the mixed lipid bilayer systems. Yet, there has been a lack of understanding on how distribution of the lipids affects the overall structure of the mixed lipid system. Therefore, this study runs fully atomistic molecular dynamics (MD) simulations of the lipid bilayer systems with two different configurations:  dispersed and segregated model. Dispersed model has lysolipid molecules evenly distributed across the structure whereas segregated model has lysolipid molecules aggregated in the middle of the structure. The system is comprised of 10 percent MPPC and 90 percent DPPC. The changes in structure through the phase transition are investigated.