Abstract
We report a study of kinetically trapped unilamellar vesicles (ULVs) of lipid mixtures composed of dimyristoyl phosphatidylcholine (DMPC), dihexanoyl phosphatidylcholine (DHPC) and (dimyristoyl phosphatidylglycerol) DMPG. Two membrane charge densities (namely, [DMPG]/[DMPC] = 0.01 and 0.001) and two solution salinities ([NaCl] = 0 and 0.2 M) are investigated. Small angle neutron scattering (SANS) is used to identify the morphology of aggregates. As high concentration samples are diluted at 50°C, thermodynamically stable multi-lamellar vesicles (MLVs) are observed for both weakly charged and high salinity solution mixtures, implying that the electrostatic interactions between bilayers are insufficient to unbind the multilamellar structure. At low temperature (i.e. 10°C) nanodiscs (also known as bicelles) or bilayered ribbons are observed and they slowly evolve into uniform-size nanoscopic unilamellar vesicles (ULVs) when incubated at 10°C over a period of ∼20 hours. The ULVs persist after being heated to 50°C, where thermodynamically stable MLVs are observed. This result clearly indicates that these ULVs are kinetically trapped and that the mechanical properties (e.g. bending rigidity) of the nanodiscs at 10°C favor the formation of nanoscopic ULVs over MLVs. From a practical point-of-view, this method of forming uniform-size ULVs may lend itself to their mass production, thus making them economically feasible for medical applications that depend on lipid-based systems for therapeutic and diagnostic purposes.
| Original language | English |
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| Title of host publication | Nanoscale Science and Engineering Forum - Core Programming Topic at the 2011 AIChE Annual Meeting |
| Publisher | AIChE |
| Pages | 231-239 |
| Number of pages | 9 |
| ISBN (Print) | 9781618397416 |
| State | Published - 2011 |
| Event | Nanoscale Science and Engineering Forum - Core Programming Topic at the 2011 AIChE Annual Meeting - Minneapolis, United States Duration: Oct 16 2011 → Oct 21 2011 |
Publication series
| Name | Nanoscale Science and Engineering Forum - Core Programming Topic at the 2011 AIChE Annual Meeting |
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Conference
| Conference | Nanoscale Science and Engineering Forum - Core Programming Topic at the 2011 AIChE Annual Meeting |
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| Country/Territory | United States |
| City | Minneapolis |
| Period | 10/16/11 → 10/21/11 |
Funding
The SANS work made use of facilities supported in part by the National Science Foundation under Agreement No. DMR-0944772. The mention of commercial products does not imply endorsement by NIST, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose. The work at ORNL’s High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, United States Department of Energy (U.S. DOE). ORNL is operated by UT–Battelle, LLC for the U.S. DOE under Contract No. DE-AC05-00OR22725. JK is partly supported through ORNL’s Laboratory Directed Research and Development (LDRD) program. MPN would like to thank for the financial support from the UConn Faculty Large Grant and the Faculty Startup fund of the Institute of Materials Science (UConn). The SANS work made use of facilities supported in part by the National Science Foundation under Agreement No. DMR-0944772. The mention of commercial products does not imply endorsement by NIST, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose. The work at ORNL's High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, United States Department of Energy (U.S. DOE). ORNL is operated by UT-Battelle, LLC for the U.S. DOE under Contract No. DE-AC05-00OR22725. JK is partly supported through ORNL's Laboratory Directed Research and Development (LDRD) program. MPN would like to thank for the financial support from the UConn Faculty Large Grant and the Faculty Startup fund of the Institute of Materials Science (UConn).