Coarse-Grained Molecular Dynamics for Copolymer-Vesicle Self-Assembly. Case Study: Sterically Stabilized Liposomes
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We carried out a series of coarse-grained molecular dynamics simulations of liposome-copolymer systems in an attempt to understand the effect of copolymer structure and concentration on vesicle closure. Coarse graining implies fewer degrees of freedom, cheaper potential calculation, smoother potential surfaces, and larger time steps. In this way reliability and accuracy of fine grained (FG), i.e., atomistic models, is combined with the efficiency of a reduced representation. Such a powerful approach helped our million atoms simulations to yield hundreds of nanoseconds trajectories starting from a randomized distribution of lipid molecules DPPC and Cholesterol plus varying concentration of copolymers with lipid mimetic units in explicit solvent (order of million water molecules). Simulation data is successfully verified against experimental DOSY-NMR results. The consistency of the theoretical evidence and experimental observation provides insight into the factors governing liposome-polymer stability with both fundamental and practical consequences.
KeywordsEthylene Oxide Ethylene Oxide Large Time Step Molecule DPPC Berendsen Barostat