Morphological Characterization of DMPC/CHAPSO Bicellar Mixtures: A Combined SANS and NMR Study

Journal Article · Sun Dec 22 23:00:00 EST 2013 · Langmuir

DOI:https://doi.org/10.1021/la402799b· OSTI ID:1114270

Li, Ming ^[1]; Morales, Hannah H. ^[2]; Katsaras, John ^[3]; Kučerka, Norbert ^[4]; Yang, Yongkun ^[1]; Macdonald, Peter M. ^[2]; Nieh, Mu-Ping ^[5]

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1. Univ. of Connecticut, Storrs, CT (United States). Inst. of Materials Science
2. Univ. of Toronto, Mississauga, ON (Canada). Dept. of Chemical and Physical Sciences
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Joint Inst. for Neutron Sciences, Biology & Soft Matter Divison; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Brock Univ., St. Catharines, ON (Canada). Dept. of Physics
4. National Research Council, Chalk River, ON (Canada). Canadian Neutron Beam Centre
5. Univ. of Connecticut, Storrs, CT (United States). Inst. of Materials Science; Univ. of Connecticut, Storrs, CT (United States). Dept. of Chemical & Biomolecular Engineering and Dept. of Biomedical Engineering

Spontaneously forming structures of a system composed of dimyristoyl phosphatidylcholine (DMPC) and 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate (CHAPSO) were studied by small-angle neutron scattering (SANS), ³¹P NMR, and stimulated echo (STE) pulsed field gradient (PFG) ¹H NMR diffusion measurements. Charged lipid dimyristoyl phosphatidylglycerol (DMPG) was used to induce different surface charge densities. The structures adopted were investigated as a function of temperature and lipid concentration for samples with a constant molar ratio of long-chain to short-chain lipids (=3). In the absence of DMPG, zwitterionic bicellar mixtures exhibited a phase transition from discoidal bicelles, or ribbons, to multilamellar vesicles either upon dilution or with increased temperature. CHAPSO-containing mixtures showed a higher thermal stability in morphology than DHPC-containing mixtures at the corresponding lipid concentrations. In the presence of DMPG, discoidal bicelles (or ribbons) were also found at low temperature and lower lipid concentration mixtures. At high temperature, perforated lamellae were observed in high concentration mixtures ( ≥ 7.5 wt %) whereas uniform unilamellar vesicles and bicelles formed in low-concentration mixtures ( ≤ 2.5 wt %), respectively, when the mixtures were moderately and highly charged. Lastly, from the results, spontaneous structural diagrams of the zwitterionic and charged systems were constructed.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); Natural Science and Engineering Research Council (NSERC) of Canada; Canadian Challenge Fund for Innovation (CFI); USDOE Laboratory Directed Research and Development (LDRD) Program
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1114270
• Journal Information: Langmuir, Journal Name: Langmuir Journal Issue: 51 Vol. 29; ISSN 0743-7463
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

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