Au Nanoparticles in Lipid Bilayers: a Comparison between Atomistic and Coarse Grained Models

TL;DR

This study compares atomistic and three coarse-grained Martini models in simulating charged nanoparticle interactions with lipid bilayers, highlighting differences in their ability to accurately describe membrane anchoring and transition energetics.

Contribution

It evaluates the performance of three Martini force field variants in modeling nanoparticle-membrane interactions, focusing on electrostatics and water polarizability effects.

Findings

All models accurately describe the metastable NP-membrane complex.

Polarizable-water Martini captures transition mechanisms and energetics.

Standard Martini underestimates free energy barriers and membrane deformations.

Abstract

The computational study of the interaction between charged, ligand-protected metal nanoparticles and model lipid membranes has been recently addressed both at atomistic and coarse grained level. Here we compare the performance of three versions of the coarse grained Martini force field at describing the nanoparticle-membrane interaction. The three coarse-grained models differ in terms of treatment of long-range electrostatic interactions and water polarizability. The NP-membrane interaction consists in the transition from a metastable NP- membrane complex, in which the NP is only partially embedded in the membrane, to a configuration in which the NP is anchored to both membrane leaflets. All the three coarse grained models provide a description of the metastable NP-membrane complex that is consistent with that obtained using an atomistic force field. As for the anchoring transition, the polarizable- water Martini correctly describes the molecular mechanisms and the energetics of the transition. The standard version of the Martini model, instead, underestimates the free energy barriers for anchoring and does not completely capture the membrane deformations involved in the transition process.