32 research outputs found
Supported Lipid Bilayers of Escherichia coli Extracted Lipids and Their Calcium Dependence
Formation of supported lipid bilayer (SLB) and additional structures of Escherichia coli (E. coli) lipids were investigated with fluorescence microscopy and atomic force microscopy. Ca2+ in the aqueous phase with concentration above 2 mM was necessary for the formation of SLB. Additional lipid structures, string-like structures, the second lipid bilayer, and multilayer stacking appeared on the first layer SLB depending on Ca2+ concentration. The bridging effect of Ca2+ between the negatively charged E. coli lipid bilayers and substrate is the dominant factor determining the two-dimensional and three-dimensional morphology of the E. coli lipid bilayer membranes
Synchrotron-radiation-stimulated etching of polydimethylsiloxane using XeF2 as a reaction gas
Synchrotron-radiation-stimulated etching of silicon elastomer polydimethylsiloxane using XeF2 as an etching gas is demonstrated
Substrate Effects on the Formation Process, Structure and Physicochemical Properties of Supported Lipid Bilayers
Supported lipid bilayers are artificial lipid bilayer membranes existing at the interface between solid substrates and aqueous solution. Surface structures and properties of the solid substrates affect the formation process, fluidity, two-dimensional structure and chemical activity of supported lipid bilayers, through the 1â2 nm thick water layer between the substrate and bilayer membrane. Even on SiO2/Si and mica surfaces, which are flat and biologically inert, and most widely used as the substrates for the supported lipid bilayers, cause differences in the structure and properties of the supported membranes. In this review, I summarize several examples of the effects of substrate structures and properties on an atomic and nanometer scales on the solid-supported lipid bilayers, including our recent reports
Surface Structure, Adsorption and Reaction on TiO2(001) in the Atomic Scale Studied by Scanning Tunneling Microscopy and Temperature Programmed Desorption
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Quenching Efficiency of Quantum Dots Conjugated to Lipid Bilayers on Graphene Oxide Evaluated by Fluorescence Single Particle Tracking
A single particle observation of quantum dots (QDs) was performed on lipid bilayers formed on graphene oxide (GO). The long-range fluorescence quenching of GO has been applied to biosensing for various biomolecules. We demonstrated the single particle observation of a QD on supported lipid bilayers in this study, aiming to detect the quenching efficiency of lipid and protein molecules in a lipid bilayer by fluorescence single particle tacking (SPT). A single lipid bilayer or double lipid bilayers were formed on GO flakes deposited on a thermally oxidized silicon substrate by the vesicle fusion method. The QDs were conjugated on the lipid bilayers, and single particle images of the QDs were obtained under the quenching effect of GO. The quenching efficiency of a single QD was evaluated from the fluorescence intensities on the regions with and without GO. The quenching efficiency reflecting the layer numbers of the lipid bilayers was obtained
Domain Localization by Graphene Oxide in Supported Lipid Bilayers
The gel-phase domains in a binary supported lipid bilayer (SLB) comprising dioleoylphosphatidylcholine (DOPC) and dipalmitoylphosphatidylcholine (DPPC) were localized on graphene oxide (GO) deposited on a SiO2/Si substrate. We investigated the distribution of the gel-phase domains and the liquid crystalline (Lα) phase regions in DOPC+DPPC-SLB on thermally oxidized SiO2/Si substrates with GO flakes to understand the mechanism of the domain localization on GO. Fluorescence microscopy and atomic force microscopy revealed that the gel-phase domains preferably distributed on GO flakes, whereas the fraction of the Lα-phase increased on the bare SiO2 surface which was not covered with the GO flakes. The gel-phase domain was condensed on GO more effectively at the lower cooling rate. We propose that nucleation of the gel-phase domain preferentially occurred on GO, whose surface has amphiphilic property, during the gel-phase domain formation. The domains of the liquid ordered (Lo) phase were also condensed on GO in a ternary bilayer containing cholesterol that was phase-separated to the Lo phase and the liquid disordered phase. Rigid domains segregates on GO during their formation process, leaving fluid components to the surrounding region of GO
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Assembly of Cell-Free Synthesized Ion Channel Molecules in Artificial Lipid Bilayer Observed by Atomic Force Microscopy
Artificial lipid bilayer systems, such as vesicles, black membranes, and supported lipid bilayers (SLBs), are valuable platforms for studying ion channels at the molecular level. The reconstitution of the ion channels in an active form is a crucial process in studies using artificial lipid bilayer systems. In this study, we investigated the assembly of the human ether-a-go-go-related gene (hERG) channel prepared in a cell-free synthesis system. AFM topographies revealed the presence of protrusions with a uniform size in the entire SLB that was prepared with the proteoliposomes (PLs) incorporating the cell-free-synthesized hERG channel. We attributed the protrusions to hERG channel monomers, taking into consideration the AFM tip size, and identified assembled structures of the monomer that exhibited dimeric, trimeric, and tetrameric-like arrangements. We observed molecular images of the functional hERG channel reconstituted in a lipid bilayer membrane using AFM and quantitatively evaluated the association state of the cell-free synthesized hERG channel