Coarse-Grained Molecular Dynamics Simulation of Heterogeneous Polysorbate 80 Surfactants and their Interactions with Small Molecules and Proteins.

Polysorbate 80 (PS80) is widely used in pharmaceutical formulations, and its commercial grades exhibit certain levels of structural heterogeneity. The objective of this study was to apply coarse-grained molecular dynamics simulations to better understand the effect of PS80 heterogeneity on micelle self-assembly, the loading of hydrophobic small molecules into the micelle core, and the interactions between PS80 and a protein, bovine serum albumin (BSA). Four representative PS80 variants with different head and tail structures were studied. Our simulations found that PS80 structural heterogeneity could affect blank micelle properties such as solvent-accessible surface area, aggregation number, and micelle aspect ratio. It was also found that hydrophobic small molecules such as ethinyl estradiol preferentially partitioned into the PS80 micelle core and PS80 dioleates formed a more hydrophobic core compared to PS80 monooleates. Furthermore, multiple PS80 molecules could bind to BSA, and PS80 heterogeneity profoundly changed the binding ratio as well as the surfactant-protein contact area.