Coarse grained study of pluronic F127: Comparison with shorter co-polymers in its interaction with lipid bilayers and self-aggregation in water

• Through coarse-grain simulations the F127/model bilayers interactions were studied.
• Initial conditions, poloxamer physical states and block lengths were considered.
• A combination of features determines the conformation adopted in each phase.
• A stable trans-membrane conformation was found for F127 and P85 poloxamers.
• F127s self-aggregate in micelle structure in water phase.

The aim of this work is to understand the interactions of the poloxamer Pluronic F127, with lipid bilayers and its ability to self-associate in an aqueous environment. Molecular dynamics simulations at the coarse-grain scale were performed to address the behavior of single Pluronic F127 and shorter poloxamers unimers in palmitoyl-oleoyl-phosphatidyl-choline model membranes. According to the initial conditions and the poly-ethylene oxide/poly-propylene oxide composition, in water phase the unimer chain collapses into a coil conformation or adopts an interphacial U-shaped – or membrane spanning – distribution. A combination of poly-propylene oxide length, and the poly-ethylene oxide ability to cover poly-propylene oxide, is determinant for the conformation adopted by the unimer in each phase. Results of the simulations showed molecular evidence of strong interaction between Pluronic F127 and model membranes both in stable U-shaped and span conformations. The knowledge of this interaction could contribute to improve drug permeation. Additionally, we investigated the aggregation of one hundred Pluronic F127 unimers in water forming a micelle-like structure, suitable to be used as drug delivery system models.

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