Control of dispersion stability of colloidal systems by the adsorption layers of amphiphilic molecules
| Project/Area Number |
12640562
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
機能・物性・材料
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| Research Institution | Kagawa University (2001)
Tokyo Metropolitan University (2000) |
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Principal Investigator |
FUKADA Kazuhiro Kagawa University, Department of Agriculture, Associate Professor, 農学部, 助教授 (60212180)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | colloidal stability / surfactant / adsorption / phospholipid / vesicle / area expansion modulus / adhension / atomic force microscape / 表面電位 / ゼータ電位 / ポリスチレンラテックス |
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| Research Abstract |
1. Turbidity and ζ-potential of negatively charged polystyrene latex (PSL) dispersions in alkyltrimethylammonium bromide solutions were measured as a function of the surfactant concentration. By the adsorption of the cationic surfactants, the ζ-potential of polystyrene particles increased with the surfactant concentration. The rapid coagulation of PSL was observed when the surfactant concentration was ca. 2 μM where ζ-potential and the surface charge of PSL were still negative. Also, it was confirmed by the direct force measurements using AFM that the adhesion energy between a polystyrene micro-sphere and silica plate in cationic surfactant solution was the largest at this surfactant concentration (2 μM). We proposed a model for the surface structure of polystyrene particles adsorbing cationic surfactant molecules.
2. Mechanical properties of bilayer membranes made of phospholipids in aqueous medium were studied as a model system of the adsorbed layers of amphiphilic molecules on colloidal particles. Giant vesicles of phospholipids were prepared by the so-called alternative current electroformation method, and the micropipet aspiration experiments were performed under the optical microscope observation to estimate the area expansion modulus of the bilayer. It was confirmed that by introducing a hydrophobic peptide, gramicidin A, into the lipid bilayers, the expansion modulus was decreased whereas it was increased when cholesterol was added into the bilayers. From these results, we could expect that the addition of gramicidin A to phospholipids may lead the positive effect for the colloidal stability of the dispersion systems because of the enhanced repulsive force between the colloid particles which originated from the undulation of adsorbed lipid layers.
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Report
(3 results)
Research Products
(3 results)
