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1.
Int J Mol Sci ; 24(9)2023 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-37175707

RESUMO

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.


Assuntos
Grafite , Bicamadas Lipídicas , Bicamadas Lipídicas/química , Dióxido de Silício , Fosfatidilcolinas/química , 1,2-Dipalmitoilfosfatidilcolina/química , Microscopia de Força Atômica
2.
Chem Rec ; 20(7): 730-742, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31944562

RESUMO

An artificial cell membrane that is composed of bilayer lipid membranes (BLMs) with transmembrane proteins incorporated within them represents a well-defined system for the analysis of membrane proteins, especially ion channel proteins that are major targets for drug design. Because the BLM system has a high compatibility with recently developed cell-free expression systems, it has attracted attention as a next-generation drug screening system. However, three issues associated with BLM systems, i. e., their instability, the need for non-volatile organic solvents and a low efficiency of ion channel incorporation, have limited their use as a drug screening platform. In this personal account, we discuss our recent approaches to address these issues based on microfabrication. We also discuss the potential for using the BLM system combined with cell-free expression systems as a drug screening system for future personalized medicine.


Assuntos
Canais Iônicos/química , Bicamadas Lipídicas/química , Avaliação Pré-Clínica de Medicamentos
3.
Biosci Biotechnol Biochem ; 84(10): 2028-2036, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32543982

RESUMO

Eukaryotic in vitro translation systems require large numbers of protein and RNA components and thereby rely on the use of cell extracts. Here we established a new in vitro translation system based on rice callus extract (RCE). We confirmed that RCE maintains its initial activity even after five freeze-thaw cycles and that the optimum temperature for translation is around 20°C. We demonstrated that the RCE system allows the synthesis of hERG, a large membrane protein, in the presence of liposomes. We also showed that the introduction of a bicistronic mRNA based on 2A peptide to RCE allowed the production of two distinct proteins from a single mRNA. Our new method thus facilitates laboratory-scale production of cell extracts, making it a useful tool for the in vitro synthesis of proteins for biochemical studies.


Assuntos
Oryza/química , Extratos Vegetais/metabolismo , Biossíntese de Proteínas , Sistema Livre de Células/metabolismo , RNA Mensageiro/genética
4.
Langmuir ; 34(24): 7201-7209, 2018 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-29788718

RESUMO

Lipid molecules such as glycolipids that are modified with hydrophilic biopolymers participate in the biochemical reactions occurring on cell membranes. Their functions and efficiency are determined by the formation of microdomains and their physical properties. We investigated the morphology and properties of domains induced by the hydrophilic-polymer-modified lipid applying a polyethylene glycol (PEG)-modified lipid as a model modified lipid. We formed supported lipid bilayers (SLBs) using a 0-10 mol % range of PEG-modified lipid concentration ( CPEG). We studied their morphology and fluidity by fluorescence microscopy, the fluorescence recovery after photobleaching method, and atomic force microscopy (AFM). Fluorescence images showed that domains rich in the PEG-modified lipid appeared and SLB fluidity decreased when CPEG ≥ 5%. AFM topographies showed that clusters of the PEG-modified lipid appeared prior to domain formation and the PEG-lipid-rich domains were observed as depressions. Frequency-modulation AFM revealed a force-dependent appearance of the PEG-lipid-rich domain.


Assuntos
Bicamadas Lipídicas/química , Lipídeos/química , Polímeros/química , Interações Hidrofóbicas e Hidrofílicas , Microscopia de Força Atômica , Microscopia de Fluorescência
5.
Langmuir ; 34(19): 5615-5622, 2018 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-29664647

RESUMO

Artificial bilayer lipid membranes (BLMs) provide well-defined systems for investigating the fundamental properties of membrane proteins, including ion channels, and for screening the effect of drugs that act on them. However, the application of this technique is limited due to the low stability and low reconstitution efficiency of the process. We previously reported on improving the stability of BLM based on the fabrication of microapertures having a tapered edge in SiO2/Si3N4 septa and efficient ion channel incorporation based on vesicle fusion accelerated by a centrifugal force. Although the BLM stability and incorporation probability were dramatically improved when these approaches were used, some BLMs were ruptured when subjected to a centrifugal force. To further improve the BLM stability, we investigated the effect of modifying the surface of the SiO2/Si3N4 septa on the stability of BLM suspended in the septa. The modified surfaces were characterized in terms of hydrophobicity, lipophobicity, and surface roughness. Diffusion coefficients of the lipid monolayers formed on the modified surfaces were also determined. Highly fluidic lipid monolayers were formed on the amphiphobic substrates that had been modified with long-chain perfluorocarbons. Free-standing BLMs formed in amphiphobic septa showed a much higher mechanical stability, including tolerance to water movement and applied centrifugal forces with and without proteoliposomes, than those formed in the septa that had been modified with a short alkyl chain. These results demonstrate that highly stable BLMs are formed when the surface of the septa has amphiphobic properties. Because highly fluidic lipid monolayers that are formed on the septa seamlessly connect with BLMs in a free-standing region, the high fluidity of the lipids contributes to decreasing potential damage to BLMs when mechanical stresses are applied. This approach to improve the BLM stability increases the experimental efficiency of the BLM systems and will contribute to the development of high-throughput platforms for functional assays of ion channel proteins.


Assuntos
Bicamadas Lipídicas/química , Canais Iônicos/química , Fusão de Membrana , Dióxido de Silício/química , Estresse Mecânico
6.
Langmuir ; 33(51): 14748-14755, 2017 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-29236511

RESUMO

The solid-substrate-dependent structure and dynamics of molecules in a supported lipid bilayer (SLB) were directly investigated via atomic force microscopy (AFM) and single particle tracking (SPT) measurements. The appearance of either vertical or horizontal heterogeneities in the SLB was found to be strongly dependent on the underlying substrates. SLB has been widely used as a biointerface with incorporated proteins and other biological materials. Both silica and mica are popular substrates for SLB. Using single-molecule dynamics, the fluidity of the upper and lower membrane leaflets was found to depend on the substrate, undergoing coupling and decoupling on the SiO2/Si and mica substrates, respectively. The anisotropic diffusion caused by the locally destabilized structure of the SLB at atomic steps appeared on the Al2O3(0001) substrate because of the strong van der Waals interaction between the SLB and the substrate. Our finding that the well-defined surfaces of mica and sapphire result in asymmetry and anisotropy in the plasma membrane is useful for the design of new plasma-membrane-mimetic systems. The application of well-defined supporting substrates for SLBs should have similar effects as cell membrane scaffolds, which regulate the dynamic structure of the membrane.


Assuntos
Bicamadas Lipídicas , Microscopia de Força Atômica , Simulação de Dinâmica Molecular , Dióxido de Silício
7.
Arch Biochem Biophys ; 605: 26-33, 2016 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-27216034

RESUMO

We investigated morphological change of an artificial lipid bilayer membrane induced by oxygen radicals which were generated by non-equilibrium atmospheric pressure plasma. Neutral oxygen species, O((3)Pj) and O2((1)Δg), were irradiated of a supported lipid bilayer existing under a buffer solution at various conditions of dose time and distances, at which the dose amounts of the oxygen species were calculated quantitatively. Observation using an atomic force microscope and a fluorescence microscope revealed that dose of the neutral oxygen species generated nanopores with the diameter of 10-50 nm in a phospholipid bilayer, and finally destructed the bilayer structure. We found that protrusions appeared on the lipid bilayer surface prior to the formation of nanopores, and we attributed the protrusions to the precursor of the nanopores. We propose a mechanism of the pore formation induced by lipid oxidation on the basis of previous experimental and theoretical studies.


Assuntos
Bicamadas Lipídicas/química , Membranas Artificiais , Nanoporos , Gases em Plasma/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Aldeídos/química , Soluções Tampão , Membrana Celular/metabolismo , Micelas , Microscopia de Força Atômica , Microscopia de Fluorescência , Nanotecnologia/métodos , Oxigênio/química , Fosfolipídeos/metabolismo , Propriedades de Superfície
8.
Langmuir ; 32(41): 10712-10718, 2016 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-27668442

RESUMO

Fluorinated lipids and surfactants are attractive biomimetic materials for the extraction and reorganization of membrane proteins because of the biological inertness of fluorocarbons. We investigated the fundamental physical properties of a partially fluorinated phospholipid (F4-DMPC), such as phase transition, area thermal expansion, and lateral lipid diffusion, to evaluate the intermolecular interaction of F4-DMPC in the hydrophobic region quantitatively on the basis of free-volume theory. Fluorescence microscope observation of the supported lipid bilayer (SLB) of F4-DMPC showed that the phase transition between the liquid crystalline and gel phases occurred at 5 °C and that the area thermal expansion coefficient was independent of the temperature near the phase transition temperature. We performed a single particle tracking of the F4-DMPC-SLB on a SiO2/Si substrate, to measure the diffusion coefficient and its temperature dependence. The apparent activation energy (E'a) of lateral lipid diffusion, which is an indicator of intermolecular interaction, was 39.1 kJ/mol for F4-DMPC, and 48.2 kJ/mol for a nonfluorinated 1,2-dioleoyl-sn-glycero-3-phosphocholine as a control. The difference of 9 kJ/mol in E'a was significant compared with the difference due to the acyl chain species among nonfluorinated phosphatidylcholine and also that caused by the addition of cholesterol and alcohol in the bilayer membranes. We quantitatively evaluated the attenuation of intermolecular interaction, which results from the competition between the dipole-induced packing effect and steric effect at the fluorocarbon segment in F4-DMPC.

9.
Langmuir ; 32(48): 12823-12832, 2016 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-27934514

RESUMO

Domain formation or compartmentalization in a lipid bilayer membrane has been thought to take place dynamically in cell membranes and play important roles in the spatiotemporal regulation of their physiological functions. In addition, the membrane skeleton, which is a protein assembly beneath the cell membrane, also regulates the properties as well as the morphology of membranes because of its role as a diffusion barrier against constitutive molecules of the membrane or as a scaffold for physiological reactions. Therefore, it is important to study the relationship between lipid bilayer membranes and proteins that form the membrane skeleton. Among cytoskeletal systems, septin is unique because it forms arrays on liposomes that contain phosphoinositides, and this property is thought to contribute to the formation of the annulus in sperm flagellum. In this study, a supported lipid bilayer (SLB) was used to investigate the effect of septin on lipid bilayers because SLBs rather than liposomes are suitable for observation of the membrane domains formed. We found that SLBs containing phosphatidylinositol (PI) reversibly form domains by decreasing the temperature and that septin affects both the formation and the disappearance of the cooling-induced domain. Septin inhibits the growth of cooling-induced domains during decreases in temperature and inhibits the dispersion and the disappearance of those domains during increases in temperature. These results indicate that septin complexes, i.e., filaments or oligomers assembling on the surface of lipid bilayer membranes, can regulate the dynamics of domain formation via their behavior as an anchor for PI molecules.


Assuntos
Membrana Celular , Bicamadas Lipídicas , Septinas/farmacologia , Transição de Fase , Temperatura
10.
Membranes (Basel) ; 13(11)2023 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-37999340

RESUMO

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.

11.
Colloids Surf B Biointerfaces ; 210: 112235, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34891064

RESUMO

Domain formation in "HLC" ternary lipid bilayers, comprising a high transition temperature (High-Tm) lipid, a Low-Tm lipid, and cholesterol (Chol), has been extensively studied as raft-resembling systems. Recently, we reported the formation of submicron domains in an "LLC" lipid bilayer, encompassing Low-Tm phosphatidylethanolamine (PE), Low-Tm phosphatidylcholine (PC), and Chol. We hypothesized that the formation of this unique domain is driven by polyunsaturated PE. In this study, we explored the effects of the degree of PE unsaturation and the double bond distribution at the sn-position on the mechanism of formation and the composition of submicron domains. Supported lipid bilayers (SLBs), comprising PE with various degrees of unsaturation, monounsaturated PC (POPC), and Chol, were investigated using fluorescence microscopy, atomic force microscopy, and the force-distance curve measurement. The area fraction of submicron domains in PE+POPC+Chol-SLB increased with the PE concentration and degree of unsaturation of the PE acyl chain. The results indicated that the submicron domains were enriched with polyunsaturated PE and were in the liquid-disordered-like state, whereas their surrounding regions were in the liquid-ordered-like state. Segregation of polyunsaturated PE from the Chol-containing region generated submicron domains in the LLC lipid bilayer. We propose a mechanism for the formation of these submicron domains based on molecular interactions involving the hydrophobic and hydrophilic parts of the bilayer membrane.


Assuntos
Bicamadas Lipídicas , Fosfatidiletanolaminas , Colesterol , Microscopia de Força Atômica , Fosfatidilcolinas
12.
Biochim Biophys Acta ; 1798(6): 1090-9, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20226163

RESUMO

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. Surprisingly high-speed Abeta aggregation of fibril formations occurred at all GM1 concentrations examined on the mica surface, but on the SiO(2) surface, only globular agglomerates formed and they formed slowly. At a GM1 concentration of 20mol%, unique triangular regions formed on the mica surface and the rapidly formed Abeta aggregations were observed only outside these regions. We have found that some unique surface-induced phase separations are induced by the GM1 clustering effects and the strong interactions between the GM1 head group and the water layer adsorbed in the ditrigonal cavities on the mica surface. The speed of Abeta40 aggregation and the shape of the agglomerates depend on the molecular conformation of GM1, which varies depending on the substrate materials. We identified the conformation that significantly accelerates Abeta40 aggregation, and we think that the detailed knowledge about the GM1 molecular conformation obtained in this work will be useful to those investigating Abeta-GM1 interactions.


Assuntos
Silicatos de Alumínio/química , Peptídeos beta-Amiloides/química , Colesterol/química , Gangliosídeo G(M1)/química , Microdomínios da Membrana/química , Multimerização Proteica , Esfingomielinas/química , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Animais , Bovinos , Colesterol/metabolismo , Simulação por Computador , Gangliosídeo G(M1)/metabolismo , Humanos , Microdomínios da Membrana/metabolismo , Dióxido de Silício/química , Esfingomielinas/metabolismo , Suínos
13.
Langmuir ; 27(16): 9662-5, 2011 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-21761843

RESUMO

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. The temporal dependence of the diffusion coefficient in the SLB on TiO(2)(100) showed that the crossover from anomalous diffusion to random diffusion occurred around 10 ms. The surface fine architecture on substrates will be applicable to induce hierarchic structures on the order of 100 nm or less, which correspond to the microcompartment size in vivo.


Assuntos
Bicamadas Lipídicas/química , Nanoestruturas/química , Nanotecnologia , Dióxido de Silício/química , Titânio/química
14.
Biomacromolecules ; 12(7): 2850-8, 2011 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-21650465

RESUMO

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. Lateral diffusion of these membrane proteins, observed by a fluorescence recovery after photobleaching (FRAP), is discussed in terms of the membrane architecture. Energy transfer from LH2 to LH1-RC within the tethered membrane was observed by steady-state fluorescence spectroscopy, indicating that the tethered membrane can mimic the natural situation.


Assuntos
Complexos de Proteínas Captadores de Luz/metabolismo , Bicamadas Lipídicas/metabolismo , Complexos de Proteínas Captadores de Luz/química , Bicamadas Lipídicas/química , Modelos Moleculares , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
15.
Biochim Biophys Acta Biomembr ; 1863(8): 183626, 2021 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-33901442

RESUMO

Recently, we reported that a ternary lipid bilayer comprising phosphatidylethanolamine (PE), phosphatidylcholine (PC), which were both derived from chicken egg, and cholesterol (Chol) generates microdomains that function as specific fusion sites for proteoliposomes. Chol-induced microdomain formation in a completely miscible lipid bilayer is an exceptional phenomenon. Numerous studies have elucidated the formation of domains in liquid ordered (Lo) and liquid disordered (Ld) phases of ternary bilayers, which comprise two partially miscible lipids and Chol. Herein, we investigated the composition and mechanism of formation of these unique microdomains in supported lipid bilayers (SLBs) using a fluorescence microscope and an atomic force microscope (AFM). We prepared ternary SLBs using egg-derived PC (eggPC), Chol and three different types of PE: egg-derived PE, 1-palmitoyl-2-oleoyl-PE, and 1,2-didocosahexaenoyl-PE (diDHPE). Fluorescence microscopy observations revealed that fluid and continuous SLBs were formed at PE concentrations (CPE) of ≥6 mol%. Fluorescence recovery after photobleaching measurement revealed that the microdomain was more fluid than the surrounding region that showed typical diffusion coefficient of the Lo phase. The microdomains were observed as depressions in the AFM topographies. Their area fraction (θ) increased with CPE, and diDHPE produced a significantly large θ among the three PEs. The microdomains in the PE+eggPC+Chol-SLBs were rich in polyunsaturated PE and were in the Ld-like phase. Associating eggPC and Chol caused polyunsaturated PE to segregate, resulting in a microdomain formation by conferring the umbrella effect on Chol, entropic effect of disordered acyl chains, and π-π interactions in the hydrophobic core.


Assuntos
Colesterol/química , Bicamadas Lipídicas/química , Microdomínios da Membrana/química , Colesterol/genética , Bicamadas Lipídicas/metabolismo , Microdomínios da Membrana/metabolismo , Microdomínios da Membrana/ultraestrutura , Microscopia de Fluorescência , Fosfatidilcolinas/química , Fosfatidilcolinas/genética , Fosfatidiletanolaminas/química , Fosfatidiletanolaminas/genética , Fosfolipídeos/química , Fosfolipídeos/genética
16.
Membranes (Basel) ; 11(5)2021 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-34063660

RESUMO

We characterized the size, distribution, and fluidity of microdomains in a lipid bilayer containing phosphatidylinositol (PI) and revealed their roles during the two-dimensional assembly of a membrane deformation protein (FBP17). The morphology of the supported lipid bilayer (SLB) consisting of PI and phosphatidylcholine (PC) on a mica substrate was observed with atomic force microscope (AFM). Single particle tracking (SPT) was performed for the PI+PC-SLB on the mica substrate by using the diagonal illumination setup. The AFM topography showed that PI-derived submicron domains existed in the PI+PC-SLB. The spatiotemporal dependence of the lateral lipid diffusion obtained by SPT showed that the microdomain had lower fluidity than the surrounding region and worked as the obstacles for the lipid diffusion. We observed the two-dimensional assembly of FBP17, which is one of F-BAR family proteins included in endocytosis processes and has the function generating lipid bilayer tubules in vitro. At the initial stage of the FBP17 assembly, the PI-derived microdomain worked as a scaffold for the FBP17 adsorption, and the fluid surrounding region supplied FBP17 to grow the FBP17 domain via the lateral molecular diffusion. This study demonstrated an example clearly revealing the roles of two lipid microregions during the protein reaction on a lipid bilayer.

17.
J Synchrotron Radiat ; 17(1): 69-74, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20029113

RESUMO

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. An extremely high etching rate of 40-50 microm (10 min)(-1) was easily obtained at an XeF(2) gas pressure of 0.2-0.4 torr. This suggests that SR etching using XeF(2) gas provides a new microfabrication technology for thick PDMS membranes, which can open new applications such as the formation of three-dimensional microfluidic circuits.


Assuntos
Fluoretos/química , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Nanotecnologia/métodos , Síncrotrons , Xenônio/química , Fluoretos/efeitos da radiação , Gases/química , Gases/efeitos da radiação , Teste de Materiais , Nanoestruturas/efeitos da radiação , Propriedades de Superfície , Raios X , Xenônio/efeitos da radiação
18.
Opt Express ; 18(9): 9733-8, 2010 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-20588823

RESUMO

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. The aim of this work is to develop a three-dimensional microfluidic channel with a special through hole, which is beneficial for cell differentiation, functionality and longevity and cannot be fabricated by conventional direct tooling techniques.

19.
Langmuir ; 26(21): 16392-6, 2010 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-20973582

RESUMO

We studied the methanol adsorption behavior of Pt nanoparticles that were vacuum-deposited on a TiO(2)(110) surface at room temperature by using an ultrahigh vacuum (UHV) scanning tunneling microscope (STM). A large number of bright spots were observed on fivefold-coordinated Ti (Ti(5c)) rows of the TiO(2)(110) surface after exposure of the Pt/TiO(2)(110) to methanol vapor. We assigned the bright spots to methoxy species. These were mobile and were found to hop along the Ti(5c) rows. In situ time-resolved STM observations of the formation and migration of the bright spots on the Pt/TiO(2)(110) were carried out in the presence of methanol. The bright spots were produced at the periphery of the Pt nanoparticles and migrated to the substrate Ti(5c) rows. We discuss the spillover process and behavior of the methoxy species on the Pt/TiO(2)(110).


Assuntos
Nanopartículas Metálicas/química , Metanol/química , Platina/química , Adsorção , Tamanho da Partícula , Propriedades de Superfície , Titânio/química , Vácuo , Volatilização
20.
Anal Bioanal Chem ; 391(8): 2703-9, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18392614

RESUMO

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.


Assuntos
Técnicas Biossensoriais/instrumentação , Canais Iônicos/química , Silício/química , Técnicas Biossensoriais/métodos , Capsaicina/farmacologia , Linhagem Celular , Humanos , Canais Iônicos/efeitos dos fármacos , Canais Iônicos/metabolismo , Rim/citologia , Rim/efeitos dos fármacos , Rim/metabolismo , Ligantes , Técnicas de Patch-Clamp/instrumentação , Técnicas de Patch-Clamp/métodos , Canais de Cátion TRPV/química , Canais de Cátion TRPV/efeitos dos fármacos , Canais de Cátion TRPV/metabolismo
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