Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: An Expanding Shell Model of Monomer Distribution
- Valparaiso Univ., IN (United States). Dept. of Physics and Astronomy
- Univ. of Memphis, Memphis, TN (United States). Inst. for Nanomaterials Development and Innovation, Dept. of Chemistry
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Structural Molecular Biology (CSMB)
- National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Center for Neutron Research; Univ. of Delaware, Newark, DE (United States). Dept. of Chemical Engineering
- Inst. Laue-Langevin (ILL), Grenoble (France)
Hydrophobic monomers partially phase separate from saturated lipids when loaded into lipid bilayers in amounts exceeding a 1:1 monomer/lipid molar ratio. This conclusion is based on the agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in an increase in bilayer thickness and a slight increase in the diameter of liposomes. A homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to an increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS), was approximately half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was intermediate between values predicted for a homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at a 1.2 monomer/lipid ratio approximately half of the monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for the directed covalent assembly of organic nanomaterials. In particular, the partial phase separation of monomers from lipids corroborates the successful creation of nanothin polymer materials with uniform imprinted nanopores. Finally, pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- DOE Contract Number:
- AC05-00OR22725; CHE-1012951; CHE-0349315; 1R01HL079147-01
- OSTI ID:
- 1081750
- Journal Information:
- Langmuir, Vol. 27, Issue 7; ISSN 0743-7463
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
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