(338f) Derivation of Coarse-Grained Lipid Potentials Using Multi-State Iterative Boltzmann Inversion

In this work, we present intermolecular potentials for coarse-grained (CG) models of the lipids present in the skin, specifically ceramides, cholesterol and free fatty acids. CG models were developed in order to make it feasible to simulate the timescales required to capture self-assembly behavior.  The potentials were derived via the multi-state iterative Boltzmann inversion (IBI) method [1]. This approach is a modification of the original iterative Boltzmann inversion method [2] that involves iteratively adjusting a CG potential such that it simultaneously matches the structure of target atomistic systems at different thermodynamic state points and/or in different thermodynamic ensembles. This approach minimizes state dependence, producing robust, generally applicable CG potentials. Here, transferable potentials have been derived for CG models of a free fatty acid, two different ceramides, and cholesterol. We also show how the multi-state IBI method allows us to develop potentials that accurately reproduce structural properties beyond the radial distribution function used in the derivation of the potentials (e.g., tilt angle, nematic order). The properties of both pre- and self-assembled CG lipids mixed with water is also explored and the behavior compared to both atomistic and experimental results.

[1] T.C. Moore, C.R. Iacovella, and C. McCabe. “Derivation of coarse-grained potentials via multistate iterative Boltzmann inversion.” (submitted)

[2] D. Reith, M. Putz, and F. Muller-Plathe, J. Comp. Chem. 24, 1624 (2003).