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Tabaei SR, Jackman JA, Kim SO, Zhdanov VP, Cho NJ. Solvent-assisted lipid self-assembly at hydrophilic surfaces: factors influencing the formation of supported membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:3125-34. [PMID: 25679066 DOI: 10.1021/la5048497] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
As a simple and efficient technique, the solvent-assisted lipid bilayer (SALB) formation method offers a versatile approach to fabricating a planar lipid bilayer on solid supports. Corresponding mechanistic aspects and the role of various governing parameters remain, however, to be better understood. Herein, we first scrutinized the effect of lipid concentration (0.01 to 5 mg/mL) and solvent type (isopropanol, n-propanol, or ethanol) on SALB formation on silicon oxide in order to identify optimal conditions for this process. The obtained fluid-phase lipid layers on silicon oxide were investigated by using the quartz crystal microbalance with dissipation monitoring, epifluorescence microscopy, and atomic force microscopy. The experimental results indicate that, in alcohol, lipid attachment to the substrate is reversible and reaches equilibrium in accordance with the bulk lipid concentration. During the solvent-exchange step, the water fraction increases and the deposited lipids are converted into planar bilayer fragments, along with the concurrent adsorption and rupture of micelles within an optimal lipid concentration range. In addition, fluid-phase lipid bilayers were successfully formed on other substrates (e.g., chrome, indium tin oxide, and titanium oxide) that are largely intractable to conventional methods (e.g., vesicle fusion). Moreover, gel-phase lipid bilayers were fabricated as well. Depending on the phase state of the lipid bilayer during fabrication, the corresponding adlayer mass varied by approximately 20% between the fluid- and gel-phase states in a manner which is consistent with the molecular packing of lipids in the two arrangements. Taken together, our findings help to explain the mechanistic details of SALB formation, optimize the corresponding procedure, and demonstrate the general utility for fabricating gel- and fluid-phase planar lipid bilayers.
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Affiliation(s)
- Seyed R Tabaei
- †School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
- ‡Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive 637553, Singapore
| | - Joshua A Jackman
- †School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
- ‡Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive 637553, Singapore
| | - Seong-Oh Kim
- †School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
- ‡Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive 637553, Singapore
| | - Vladimir P Zhdanov
- †School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
- ‡Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive 637553, Singapore
- ∥Boreskov Institute of Catalysis, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Nam-Joon Cho
- †School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
- ‡Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive 637553, Singapore
- §School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive 637459, Singapore
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Abstract
The impact of type 1 diabetes mellitus (T1DM) on a comprehensive neurochemical profile of the human brain has not been reported yet. Our previous proton magnetic resonance spectroscopy ((1)H-MRS) studies on T1DM were focused exclusively on the assessment of brain glucose levels. In this study, we reexamined our previously acquired data to investigate concentration differences of a broad range of neurochemicals in T1DM subjects relative to nondiabetic controls. We selected MRS data from 13 subjects (4 F/9 M, age = 41 ± 11 years, body mass index = 26 ± 3 kg/m(2)) with well-controlled T1DM (disease duration = 22 ± 12 years, A1C = 7.5% ± 2.0%) and 32 nondiabetic controls (14 F/18 M, age = 36 ± 10 years, body mass index = 27 ± 6 kg/m(2)) acquired during a hyperglycemic clamp (target [Glc]plasma = 300 ± 15 mg/dL). The (1)H-MR spectra were collected from two 15.6-mL voxels localized in gray-matter-rich occipital lobe and in white-matter-rich parieto-occipital region using ultra-short echo-time STEAM at 4 T. LCModel analysis allowed reliable quantification of 17 brain metabolites. Lower levels of N-acetylaspartate (by 6%, P=0.007) and glutamate (by 6%, P=0.045) were observed in the gray matter of T1DM patients as compared with controls, which might indicate a partial neuronal loss or dysfunction as a consequence of long-term T1DM. No other differences in metabolites were observed between subjects with T1DM and controls.
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Petr A, Grossmann G, Klose G, Ahlnäs T, Götze T. Rotational motions in n-hexane phosphon c acid diethyl ester studied combining 2H, 13C, and 31P NMR. Analysis of the phosphorus-31 spin-lattice relaxation. ACTA ACUST UNITED AC 1986. [DOI: 10.1016/0022-2364(86)90431-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Koga K, Kanazawa Y. Head group interaction in phosphatidylcholine micelles studied by 14N-nuclear magnetic resonance. Chem Phys Lipids 1984. [DOI: 10.1016/0009-3084(84)90068-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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