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Nguyen MHL, Dziura D, DiPasquale M, Castillo SR, Kelley EG, Marquardt D. Investigating the cut-off effect of n-alcohols on lipid movement: a biophysical study. SOFT MATTER 2023. [PMID: 37357554 DOI: 10.1039/d2sm01583h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
Cellular membranes are responsible for absorbing the effects of external perturbants for the cell's survival. Such perturbants include small ubiquitous molecules like n-alcohols which were observed to exhibit anesthetic capabilities, with this effect tapering off at a cut-off alcohol chain length. To explain this cut-off effect and complement prior biochemical studies, we investigated a series of n-alcohols (with carbon lengths 2-18) and their impact on several bilayer properties, including lipid flip-flop, intervesicular exchange, diffusion, membrane bending rigidity and more. To this end, we employed an array of biophysical techniques such as time-resolved small angle neutron scattering (TR-SANS), small angle X-ray scattering (SAXS), all atomistic and coarse-grained molecular dynamics (MD) simulations, and calcein leakage assays. At an alcohol concentration of 30 mol% of the overall lipid content, TR-SANS showed 1-hexanol (C6OH) increased transverse lipid diffusion, i.e. flip-flop. As alcohol chain length increased from C6 to C10 and longer, lipid flip-flop slowed by factors of 5.6 to 32.2. Intervesicular lipid exchange contrasted these results with only a slight cut-off at alcohol concentrations of 30 mol% but not 10 mol%. SAXS, MD simulations, and leakage assays revealed changes to key bilayer properties, such as bilayer thickness and fluidity, that correlate well with the effects on lipid flip-flop rates. Finally, we tie our results to a defect-mediated pathway for alcohol-induced lipid flip-flop.
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Affiliation(s)
- Michael H L Nguyen
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
| | - Dominik Dziura
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
| | - Mitchell DiPasquale
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
| | - Stuart R Castillo
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
| | - Elizabeth G Kelley
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
- Department of Physics, University of Windsor, Windsor, Ontario, Canada.
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Minkara MS, Josephson TR, Venteicher CL, Greenvall BR, Lindsey RK, Koenig PH, Siepmann JI. Nonane and Hexanol Adsorption in the Lamellar Phase of a Nonionic Surfactant: Molecular Simulations and Comparison to Ideal Adsorbed Solution Theory. J Phys Chem B 2022; 126:3940-3949. [PMID: 35594369 DOI: 10.1021/acs.jpcb.2c02871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Adsorption of n-nonane/1-hexanol (C9/C6OH) mixtures into the lamellar phase formed by a 50/50 w/w triethylene glycol mono-n-decyl ether (C10E3)/water system was studied using configurational-bias Monte Carlo simulations in the osmotic Gibbs ensemble. The interactions were described by the Shinoda-Devane-Klein coarse-grained force field. Prior simulations probing single-component adsorption indicated that C9 molecules preferentially load near the center of the bilayer, increasing the bilayer thickness, whereas C6OH molecules are more likely to be found near the interface of the polar and nonpolar moieties, swelling the bilayer in the lateral dimension. Here, we extend this work to binary C9/C6OH adsorption to probe whether the difference in the spatial preferences may lead to a synergistic effect and enhanced loadings for the mixture. Comparing loading trends and the thermodynamics of binary adsorption to unary adsorption reveals that C9-C9 interactions lead to the largest enhancement, whereas C9-C6OH and C6OH-C6OH interactions are less favorable for this bilayer system. Ideal adsorbed solution theory yields satisfactory predictions of the binary loading.
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Affiliation(s)
- Mona S Minkara
- Department of Bioengineering, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States.,Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States
| | - Tyler R Josephson
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States.,Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250, United States
| | - Connor L Venteicher
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States
| | - Benjamin R Greenvall
- Department of Bioengineering, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Rebecca K Lindsey
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States
| | - Peter H Koenig
- Computational Chemistry, Modeling and Simulation, The Procter and Gamble Company, 8256 Union Centre Blvd, West Chester, Ohio 45069, United States
| | - J Ilja Siepmann
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States.,Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455-0132, United States
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