Diblock copolymer bilayers as model for polymersomes: A coarse grain approach

Abstract

This paper presents a new model for polymersomes developed using a poly(ethylene oxide)-poly(butadiene) diblock copolymer bilayer. The model is based on a coarse-grained approach using the MARTINI force field. Since no MARTINI parameters exist for poly(butadiene), we have refined these parameters using quantum mechanical calculations and molecular dynamics simulations. The model has been validated using extensive molecular dynamics simulations in systems with several hundred polymer units and reaching up to 6 μs. These simulations show that the copolymer coarse grain model self-assemble into bilayers and that NPT and NPT ensemble runs reproduce key structural and mechanical experimental properties for different copolymer length chains with a similar hydrophilic weight fraction.

Study of the Lamellar and Micellar Phases of Pluronic F127: A Molecular Dynamics Approach

“…Under the described conditions, we did not observe transitions between U and S shapes in either direction during the simulation time. Nevertheless, different from what happens with lipid bilayers and other polymer-based systems [33,40], an amorphous core was present, where PPO and PEO beads coexisted. In Figure 7, representative snapshots of the two lamellar systems where the complex core structure can be observed are presented.…”

“…Density profiles are an appropriate measurement for the structural characterization of these systems [19,20,[33][34][35]. For the micellar systems, the radial mass density profiles (rMDPs) were computed by dividing the systems into spherical shells along the radial direction centered at the micellar hydrophobic core and calculating the average density on the respective shells.…”

Molecular Dynamics Simulations to Study Drug Delivery Systems

“…However, since polymersome sizes often range from 100 nm up to the micron diameter size it is difficult to simulate, even at the coarse grain level, a big polymersome. In this direction, the simulation of polymeric bilayers and small polymersomes at a CG level would make possible to study key mechanical and structural properties to better develop these kinds of drug delivery systems, as recently explored by us [12]. Moreover, these simulations are useful to shed light into the effects of the incorporation of model drugs (such as neutral and protonated prilocaine), as we explore in a work-in-progress study.…”

“…However, it is argued that in simulations, periodic boundary conditions limit the bilayer undulations that impact the interpretation of the surface tension. In this way, full relaxation of the simulation box (NPT ensemble) is the most used for these kinds of systems [7,[10][11][12][13]].…”

Understanding Conformational Dynamics of Complex Lipid Mixtures Relevant to Biology

“…2017). A polymersome was built up with 936 PL-L121 molecules, arranged in vesicle shape as illustrated in Fig.…”