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Minimal Coarse-Grained Modeling toward Implicit Solvent Simulation of Generic Bolaamphiphiles
Published in American Chemical Society
PMID: 32181665
Volume: 124
Issue: 14
Pages: 2938 - 2949
A dual-site dimer model of bola or bipolar amphiphiles is developed based on an earlier single-site model of monopolar amphiphiles [Dey, S.; Saha, J. Phys. Rev. E 2017, 95, 023315]. This model incorporates both the hydrophobic effect and the hydration force in its anisotropic site-site interactions, thus obviating the need to simulate the water particles explicitly. Such economy of sites and absence of explicit solvents enable molecular dynamics simulations to achieve mesoscopic length and time scales unattainable by any bead-spring model or explicit solvent computations. Our model, however, applies to generic bolas only because the gain in scale can only be obtained by sacrificing the resolution of detailed molecular structures. Thanks to a pivoted dimer architecture, our model can incorporate the essential flexibility of bolas, which leads to their loop or U-shaped conformers. Rigid bolas can also be modeled by the same dimer simply by constraining the rotation about the pivot. Flexible model bolas show fast, spontaneous self-assembly into experimentally observed nanostructures such as micelles and rods. Tightly packed yet fluid monolayers can also be formed from these flexible dimers. Model bolalipids are seen to be less diffusive and produce thicker layers compared to their monopolar counterparts. Bilayers composed of monopolar model lipids show increased stability in the presence of membrane-spanning bolas. Rigid bolas, though achiral themselves, show self-assembly into helical rods. As all these observations agree with well-known characteristics of archaeal lipids and synthetic bolaamphiphiles, our model promises to be useful for mesoscale simulations of bolas in the context of research in lyotropic liquid crystals, biomimetics, drug delivery, and low-molecular-weight hydrogelators. © 2020 American Chemical Society.
About the journal
JournalData powered by TypesetJournal of Physical Chemistry B
PublisherData powered by TypesetAmerican Chemical Society