Publications by authors named "Chiho Kataoka-Hamai"

This study investigated the incorporation of triacylglycerol droplets in the bilayers of giant unilamellar vesicles (GUVs) using four triacylglycerols and four phosphatidylcholines by confocal laser scanning microscopy. The triacylglycerol droplets were incorporated between the monolayer leaflets of the GUVs. Among the spherical droplets protruding on only one side of the bilayers, the droplets bound to the outer leaflets outnumbered those bound to the inner leaflets.

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Lipid droplets are fat storage organelles that consist of a neutral lipid core surrounded by a phospholipid monolayer. Because of their important biological functions, reconstituting model lipid droplets in synthetic phospholipid membranes is of great interest. In the present study, we investigated the incorporation of triacylglycerol droplets into glass-supported phospholipid bilayers by using fluorescence microscopy.

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A solid-state potentiometric biosensor based on the organic and inorganic mixed phase modification of a silver surface is proposed. Stabilization of the electromotive force and functionalization with biomolecules on the sensing surface were simultaneously achieved using silver chloride chemically deposited with 1,3-diaminopropanetetraacetic acid ferric ammonium salt monohydrate and a self-assembled monolayer with oligonucleotide probes, respectively. The formation of silver chloride and adsorption of alkanethiol on the silver surface were confirmed with X-ray photoelectron spectroscopy.

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Phospholipid monolayers formed at oil-water interfaces are used for various biological applications. However, monolayer structures are not well understood. Herein, we investigated hydrocarbon partitioning in 1-palmitoyl-2-oleoyl--glycero-3-phosphocholine monolayers formed at hydrocarbon-water interfaces using fluorescence microscopy and pendant drop tensiometry.

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Phospholipid monolayers formed at oil-water interfaces have been used to explore biological interface properties. Thus, monolayer systems need to be quantitatively understood. Previously, we investigated the formation of 1-palmitoyl-2-oleoyl--glycero-3-phosphocholine (POPC) monolayers at silicone oil-water interfaces to determine the dependence of interfacial tension, γ, on the area per lipid, , compared to that of the closely packed monolayers, .

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Giant unilamellar vesicles (GUVs) adsorb to a solid surface and rupture to form a planar bilayer patch. These bilayer patches are used to investigate the properties and functions of biological membranes. Therefore, it is crucial to understand the mechanisms of GUV adsorption.

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Phospholipid monolayers at oil-water interfaces are used for various biological applications and often formed by vesicle adsorption. However, the adsorbed structures are not well characterized; therefore, fundamental investigation on vesicle adsorption behavior is necessary for correct understanding of the monolayer systems. Herein, we investigated the adsorption of phosphatidylcholine vesicles onto silicone oil-water interfaces using fluorescence microscopy and pendant drop tensiometry.

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Phospholipid monolayers at oil-water interfaces are often obtained via vesicle adsorption. However, the interaction mechanisms of vesicles with these oil-water interfaces remain unclear. Herein, we studied the adsorption of giant unilamellar vesicles (GUVs) of approximately 2-5 μm diameter onto silicone oil-water interfaces and glass surfaces modified with hexamethyldisilazane (HMDS) and octadecyltrimethoxysilane (ODTMS) using fluorescence microscopy.

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Binding of amphiphilic molecules to supported lipid bilayers (SLBs) often results in lipid fibril extension from the SLBs. Previous studies proposed that amphiphiles with large and flexible hydrophilic regions trigger lipid fibril formation in SLBs by inducing membrane curvature via their hydrophilic regions. However, no experimental studies have verified this mechanism of fibril formation.

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Modulation of cell adhesion by synthetic materials is useful for a wide range of biomedical applications. Here, we characterized cell adhesion mediated by a semisynthetic molecule, cholesteryl-modified gelatin (chol-gelatin). We found that this hybrid molecule facilitated cell adhesion by connecting two apposed membranes via multiple cholesterol moieties on the gelatin molecules, whereas unmodified gelatin did not bind to cell membranes.

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Supported lipid bilayers (SLBs) are often formed by spontaneous vesicle rupture and fusion on a solid surface. A well-characterized rupture mechanism for isolated vesicles is pore nucleation and expansion in the solution-exposed nonadsorbed area. In contrast, pore formation in the adsorbed bilayer region has not been investigated to date.

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Various properties of supported lipid bilayers such as diffusion and lipid partitioning are well characterized. However, little attention has been paid to their molecular packing density. In this work, the adsorption of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) vesicles on glass and silicon dioxide was investigated using fluorescence microscopy, quartz crystal microbalance-dissipation (QCM-D), and atomic force microscopy.

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T cell receptor (TCR) phosphorylation requires the kinase Lck and phosphatase CD45. CD45 activates Lck by dephosphorylating an inhibitory tyrosine of Lck to relieve autoinhibition. However, CD45 also dephosphorylates the TCR, and the spatial exclusion of CD45 from TCR clustering in the plasma membrane appears to attenuate this negative effect of CD45.

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Supported phospholipid bilayers can be formed by established methods such as vesicle fusion and the Langmuir-Blodgett (LB) technique. However, challenges remain in regards to creating supported bilayers from various lipid compositions, using various support surfaces, and incorporating membrane proteins. Here we report a detergent removal method as an alternative means of supported bilayer formation.

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The application of field-effect devices to biosensors has become an area of intense research interest. An attractive feature of field-effect sensing is that the binding or reaction of biomolecules can be directly detected from a change in electrical signals. The integration of such field-effect devices into cell membrane mimics may lead to the development of biosensors useful in clinical and biotechnological applications.

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The adsorption of positively charged supported lipid bilayers (SLBs) on field-effect devices was studied using various salt solutions to make it possible to understand the signal generation mechanisms of the devices. The flat-band voltage change that occurred with SLB formation was dependent on the type of monovalent cations contained in the solution. Zeta potential data showed that the intrinsic charge of the bilayers was almost constant in the presence of any of the examined alkali ions.

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We describe an electronic detection method for charged lipid bilayers supported on a Si 3N 4/SiO 2/Si substrate. The flat-band voltage was used to monitor the charge of the bilayers. We show that the flat-band voltage varies with lipid adsorption depending on the polarity and mole ratio of the charged lipids, the salt concentration, and the surface coverage.

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