Surface characteristics and electrical properties of PMMA chips for incubation-type planar-patch-clamp biosensors.

Polymethylmethacrylate (PMMA) plates were successfully applied as sensor chips in an incubation-type planar patch clamp (IPPC). Hot embossing both sides formed the PMMA plates, and a focused ion beam realized micropores. The low seal resistance of the IPPC was investigated by analyzing the surface roughness of the chips.

Positioning of the sensor cell on the sensing area using cell trapping pattern in incubation type planar patch clamp biosensor.

Positioning the sensor cell on the micropore of the sensor chip and keeping it there during incubation are problematic tasks for incubation type planar patch clamp biosensors. To solve these problems, we formed on the Si sensor chip's surface a cell trapping pattern consisting of a lattice pattern with a round area 5 μm deep and with the micropore at the center of the round area. The surface of the sensor chip was coated with extra cellular matrix collagen IV, and HEK293 cells on which a chimera molecule of channel-rhodopsin-wide-receiver (ChR-WR) was expressed, were then seeded.

Anomalous diffusion in supported lipid bilayers induced by oxide surface nanostructures.

Hierarchic structure and anomalous diffusion on submicrometer scale were introduced into an artificial cell membrane, and the spatiotemporal dependence of lipid diffusion was visualized on nanostructured oxide surfaces. We observed the lipid diffusion in supported lipid bilayers (SLBs) on step-and-terrace TiO(2)(100) and amorphous SiO(2)/Si surfaces by single molecule tracking (SMT) method. The SMT at the time resolution of 500 μs to 30 ms achieved observation of the lipid diffusion over the spatial and temporal ranges of 100 nm/millisecond to 1 μm/second.

Construction and structural analysis of tethered lipid bilayer containing photosynthetic antenna proteins for functional analysis.

The construction and structural analysis of a tethered planar lipid bilayer containing bacterial photosynthetic membrane proteins, light-harvesting complex 2 (LH2), and light-harvesting core complex (LH1-RC) is described and establishes this system as an experimental platform for their functional analysis. The planar lipid bilayer containing LH2 and/or LH1-RC complexes was successfully formed on an avidin-immobilized coverglass via an avidin-biotin linkage. Atomic force microscopy (AFM) showed that a smooth continuous membrane was formed there.

Extracellular and intraneuronal HMW-AbetaOs represent a molecular basis of memory loss in Alzheimer's disease model mouse.

Background: Several lines of evidence indicate that memory loss represents a synaptic failure caused by soluble amyloid β (Aβ) oligomers. However, the pathological relevance of Aβ oligomers (AβOs) as the trigger of synaptic or neuronal degeneration, and the possible mechanism underlying the neurotoxic action of endogenous AβOs remain to be determined.

Results: To specifically target toxic AβOs in vivo, monoclonal antibodies (1A9 and 2C3) specific to them were generated using a novel design method.

The PDMS-based microfluidic channel fabricated by synchrotron radiation stimulated etching.

Micro pattern on PDMS surface has been achieved by using synchrotron radiation (SR) stimulated etching. The experimental results indicated that SR stimulated etching has many advantages, such as extremely high etching rate (as large as 40-50 mum per 10 min), area-selectivity and anisotropy at room temperature, high spatial resolution. Combining the SR stimulated etching with photolithography, a PDMS-based microfluidic channel was obtained.

Surface-induced phase separation of a sphingomyelin/cholesterol/ganglioside GM1-planar bilayer on mica surfaces and microdomain molecular conformation that accelerates Abeta oligomerization.

Ganglioside GM1 mediates the amyloid beta (Abeta) aggregation that is the hallmark of Alzheimer's disease (AD). To investigate how ganglioside-containing lipid bilayers interact with Abeta, we examined the interaction between Abeta40 and supported planar lipid bilayers (SPBs) on mica and SiO(2) substrates by using atomic force microscopy, fluorescence microscopy, and molecular dynamics computer simulations. These SPBs contained several compositions of sphingomyelin, cholesterol, and GM1 and were treated at physiological salt concentrations.

Synchrotron-radiation-stimulated etching of polydimethylsiloxane using XeF(2) as a reaction gas.

The synchrotron radiation (SR) stimulated etching of silicon elastomer polydimethylsiloxane (PDMS) using XeF(2) as an etching gas has been demonstrated. An etching system with differential pumps and two parabolic focusing mirrors was constructed to perform the etching. The PDMS was found to be effectively etched by the SR irradiation under the XeF(2) gas flow, and the etching process was area-selective and anisotropic.

Polymerized lipid bilayers on a solid substrate: morphologies and obstruction of lateral diffusion.

Substrate supported planar lipid bilayers (SPBs) are versatile models of the biological membrane in biophysical studies and biomedical applications. We previously developed a methodology for generating SPBs composed of polymeric and fluid phospholipid bilayers by using a photopolymerizable diacetylene phospholipid (DiynePC). Polymeric bilayers could be generated with micropatterns by conventional photolithography, and the degree of polymerization could be controlled by modulating UV irradiation doses.

Lipid bilayer membrane with atomic step structure: supported bilayer on a step-and-terrace TiO2(100) surface.

The formation of a supported planar lipid bilayer (SPLB) and its morphology on step-and-terrace rutile TiO 2(100) surfaces were investigated by fluorescence microscopy and atomic force microscopy. The TiO 2(100) surfaces consisting of atomic steps and flat terraces were formed on a rutile TiO 2 single-crystal wafer by a wet treatment and annealing under a flow of oxygen. An intact vesicular layer formed on the TiO 2(100) surface when the surface was incubated in a sonicated vesicle suspension under the condition that a full-coverage SPLB forms on SiO 2, as reported in previous studies.

Incubation type Si-based planar ion channel biosensor.

A new planar-type ion channel biosensor with the function of cell culture has been fabricated using silicon on an insulator substrate as the sensor chip material. Coating of the sensor chip with fibronectin was essentially important for cell incubation on the chip. Although the seal resistance was quite low (approximately 7 Mohms) compared with the pipette patch-clamp gigaohm seal, the whole-cell channel current of the transient receptor potential vanilloid type 1 (TRPV1) channel expressing HEK293 cells was successfully observed, with a good signal-to-noise ratio, using capsaicin as a ligand molecule.

Formation of high-resistance supported lipid bilayer on the surface of a silicon substrate with microelectrodes.

We have developed two basic technologies for fabrication of supported planar lipid bilayer membrane ion channel biosensors: a defect-free lipid bilayer formation on the substrate surface with electrode pores and a patterning technique for the hydrophobic self-assembled-monolayer to form the guard ring that reduces the lipid bilayer edge-leak current. The importance of the supported-membrane structure to achieve low noise and high-speed performance is suggested on the basis of the observed relation between the single-ion-channel current noise and the pore size.

Synchrotron-radiation-stimulated etching of SiO2 thin films with a tungsten nano-pillar mask.

A nano-pattern of SiO(2) on a Si (100) surface has been demonstrated by synchrotron-radiation-stimulated etching with a tungsten nano-pillar mask. The reaction gas was a mixture of SF(6) and O(2). The mask was fabricated using a focused ion beam with W(CO)(6) as the source gas.

Supported phospholipid bilayer formation on hydrophilicity-controlled silicon dioxide surfaces.

We investigated the influence of surface hydroxyl groups (-OHs) on the supported planar phospholipid bilayer (SPB) formation and characteristics. We prepared SiO2 surfaces with different hydrophilicity degree by annealing the SiO2 layer on Si(100) formed by wet chemical treatments. The hydrophilicity reduced with irreversible thermal desorption of -OHs.

Lipid membrane formation by vesicle fusion on silicon dioxide surfaces modified with alkyl self-assembled monolayer islands.

Using atomic force microscopy, we have investigated the formation of the dipalmitoylphosphatidylcholine (DPPC) membrane by the vesicle fusion method on SiO2 surfaces modified with self-assembled monolayer (SAM) islands of octadecyltrichlorosilane (OTS) with sizes comparable to those of the vesicles. OTS-SAM islands with various sizes and coverages can be constructed on the SiO2 surfaces prepared by thermal oxidation followed by partial hydroxylation in a H2O2/H2SO4 solution. When vesicles are sufficiently smaller than the SiO2 domains, DPPC bilayers and DPPC/OTS layers form on the SiO2 and OTS domains, respectively.