Membrane

Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Membrane

  • acetate membrane
  • acrosomal membrane
  • active membrane
  • al2o3 membrane
  • alumina membrane
  • amniotic membrane
  • anion-exchange membrane
  • anti-glomerular basement membrane
  • apical cell membrane
  • apical membrane
  • artificial membrane
  • asymmetric membrane
  • asymmetric polyimide membrane
  • bacterial cell membrane
  • bacterial membrane
  • barrier membrane
  • basal membrane
  • basement membrane
  • basilar membrane
  • basolateral membrane
  • bilayer lipid membrane
  • bilayer membrane
  • bioabsorbable collagen membrane
  • biological membrane
  • bioresorbable membrane
  • blend membrane
  • border membrane
  • bruch membrane
  • brush border membrane
  • brush-border membrane
  • canalicular membrane
  • carbon membrane
  • catalytic membrane
  • cation exchange membrane
  • cell membrane
  • cell plasma membrane
  • cellular membrane
  • cellulose acetate membrane
  • cellulose membrane
  • ceramic membrane
  • chick chorioallantoic membrane
  • chick embryo chorioallantoic membrane
  • chitosan membrane
  • chloroplast membrane
  • chorioallantoic membrane
  • choroidal neovascular membrane
  • collagen membrane
  • commercial membrane
  • composite membrane
  • conducting membrane
  • copolymer membrane
  • cytoplasmic membrane
  • dendritic membrane
  • detergent-resistant membrane
  • dialysis membrane
  • double membrane
  • egg membrane
  • elastic membrane
  • electrolyte membrane
  • embryo chorioallantoic membrane
  • endoplasmic reticulum membrane
  • endosomal membrane
  • envelope membrane
  • epiretinal membrane
  • epithelial membrane
  • eptfe membrane
  • er membrane
  • erythrocyte membrane
  • exchange membrane
  • fetal membrane
  • fiber membrane
  • fibrous membrane
  • filter membrane
  • flexible membrane
  • fuel cell membrane
  • fuel-cell membrane
  • glomerular basement membrane
  • hepatocyte membrane
  • hippocampal membrane
  • hollow fiber membrane
  • hollow-fiber membrane
  • human fetal membrane
  • hybrid membrane
  • hydrogel membrane
  • hydrophobic membrane
  • inner membrane
  • inner mitochondrial membrane
  • intact membrane
  • intact plasma membrane
  • internal limiting membrane
  • internal membrane
  • intracellular membrane
  • ion-exchange membrane
  • latent membrane
  • lateral membrane
  • limiting membrane
  • lipid bilayer membrane
  • lipid membrane
  • liposomal membrane
  • liposome membrane
  • liquid membrane
  • luminal membrane
  • lysosomal membrane
  • matrix membrane
  • microfiltration membrane
  • microporou membrane
  • microsomal membrane
  • mitochondrial inner membrane
  • mitochondrial membrane
  • model membrane
  • modified membrane
  • mucosal membrane
  • mucous membrane
  • muscle membrane
  • nafion membrane
  • nanofibrou membrane
  • nanofiltration membrane
  • native membrane
  • neovascular membrane
  • neuronal membrane
  • nuclear membrane
  • nylon membrane
  • outer bacterial membrane
  • outer limiting membrane
  • outer membrane
  • outer mitochondrial membrane
  • oxide membrane
  • peritoneal membrane
  • peritrophic membrane
  • phospholipid membrane
  • pit membrane
  • plant plasma membrane
  • plasma membrane
  • platelet membrane
  • polycarbonate membrane
  • polyimide membrane
  • polymer electrolyte membrane
  • polymer membrane
  • polymeric membrane
  • polysulfone membrane
  • porous membrane
  • postsynaptic membrane
  • prepared membrane
  • presynaptic membrane
  • proton conducting membrane
  • proton exchange membrane
  • proton-conducting membrane
  • proton-exchange membrane
  • purple membrane
  • pvdf membrane
  • rbc membrane
  • red cell membrane
  • resorbable membrane
  • reticulum membrane
  • round window membrane
  • sarcolemmal membrane
  • schneiderian membrane
  • selective membrane
  • semipermeable membrane
  • separation membrane
  • silica membrane
  • silicon membrane
  • sinus membrane
  • sperm membrane
  • sperm plasma membrane
  • supported liquid membrane
  • supported membrane
  • surface membrane
  • synaptic membrane
  • synaptosomal membrane
  • synovial membrane
  • synthetic membrane
  • target membrane
  • tested membrane
  • thin membrane
  • thylakoid membrane
  • tubular membrane
  • ultrafiltration membrane
  • undulating membrane
  • vacuolar membrane
  • vascular basement membrane
  • vesicle membrane
  • vitelline membrane
  • window membrane
  • zeolite membrane
  • zwitterionic membrane

  • Terms modified by Membrane

  • membrane affinity
  • membrane anchor
  • membrane anchoring
  • membrane antigen
  • membrane area
  • membrane association
  • membrane asymmetry
  • membrane attack complex
  • membrane bilayer
  • membrane binding
  • membrane bioreactor
  • membrane breakdown
  • membrane ca2+
  • membrane ca2+ channel
  • membrane channel
  • membrane characteristic
  • membrane charge
  • membrane cholesterol
  • membrane chromatography
  • membrane cofactor protein
  • membrane compartment
  • membrane complex
  • membrane component
  • membrane composition
  • membrane conductance
  • membrane consisting
  • membrane current
  • membrane damage
  • membrane decrease
  • membrane decreased
  • membrane degradation
  • membrane depolarization
  • membrane disease
  • membrane disruption
  • membrane distillation
  • membrane domain
  • membrane dynamics
  • membrane electrode
  • membrane electrode assembly
  • membrane elevation
  • membrane environment
  • membrane enzyme
  • membrane excitability
  • membrane exposure
  • membrane expression
  • membrane extension
  • membrane extraction
  • membrane filter
  • membrane filtration
  • membrane fluidity
  • membrane flux
  • membrane formation
  • membrane fouling
  • membrane fraction
  • membrane fractionation
  • membrane fuel cell
  • membrane function
  • membrane fusion
  • membrane glycoprotein
  • membrane h+
  • membrane hyperpolarization
  • membrane inlet mass spectrometry
  • membrane insertion
  • membrane integration
  • membrane integrity
  • membrane interaction
  • membrane interface
  • membrane introduction mass spectrometry
  • membrane isolated
  • membrane layer
  • membrane level
  • membrane lipid
  • membrane lipid composition
  • membrane lipid peroxidation
  • membrane localization
  • membrane material
  • membrane matrix
  • membrane method
  • membrane microdomain
  • membrane mimetic
  • membrane model
  • membrane models
  • membrane module
  • membrane morphology
  • membrane na+
  • membrane organization
  • membrane orientation
  • membrane oxygenation
  • membrane patch
  • membrane peeling
  • membrane pemphigoid
  • membrane perforation
  • membrane performance
  • membrane permeability
  • membrane permeabilization
  • membrane perturbation
  • membrane phase
  • membrane phospholipid
  • membrane polarization
  • membrane pore
  • membrane pore size
  • membrane potential
  • membrane potential change
  • membrane preparation
  • membrane process
  • membrane property
  • membrane protein
  • membrane protein complex
  • membrane protein expression
  • membrane protein structure
  • membrane proteome
  • membrane protrusion
  • membrane raft
  • membrane reactor
  • membrane reactor performance
  • membrane receptor
  • membrane reformer
  • membrane resistance
  • membrane rupture
  • membrane separation
  • membrane separation process
  • membrane skeleton
  • membrane specialization
  • membrane stability
  • membrane staining
  • membrane sterol
  • membrane stretch
  • membrane structure
  • membrane surface
  • membrane surface area
  • membrane swelling
  • membrane system
  • membrane targeting
  • membrane technology
  • membrane tension
  • membrane thickening
  • membrane thickness
  • membrane traffic
  • membrane trafficking
  • membrane translocation
  • membrane transplantation
  • membrane transport
  • membrane transport protein
  • membrane transporter
  • membrane type
  • membrane used
  • membrane vesicle
  • membrane voltage
  • membrane zone

  • Selected Abstracts


    STUDY ON IMPROVEMENT OF THE QUALITY IN CHINESE NEW-TYPE LIQUOR BY PERVAPORATION WITH POLYDIMETHYLSILOXANE MEMBRANE

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2007
    ER SHI
    ABSTRACT A composite polydimethylsiloxane (PDMS) membrane was used to separate aroma compounds from Chinese new-type liquor by pervaporation at 30, 35 and 40C and 10-mmHg downstream pressure. The gas chromatography analysis of aroma compounds in the retentate and permeate showed that PDMS membrane had excellent separation performance. Separation efficiencies for five kinds of esters (except ethyl lactate) and acetal in the original liquor are 100%, over 70% for alcohols (except methanol) and above 87% for aldehyde. The average flux for ethanol reached 3,539 g/m2 · h at 40C. Sensory analysis of the separated ingredients indicates that the sensory quality of the new liquor was significantly superior to that of the original liquor. Experiments suggest that pervaporation is a promising technique for the improvement of Chinese new-type liquor in terms of its flavor. [source]


    THE FOULING AND CLEANING OF ULTRAFILTRATION MEMBRANES DURING THE FILTRATION OF MODEL TEA COMPONENT SOLUTIONS

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2007
    DAN WU
    ABSTRACT Proteins and polyphenols are the principal fouling constituents in the ultrafiltration (UF) of black tea liquor. The aim of this study was to determine the relative importance of individual components in the fouling process, to investigate any synergetic interactions that were occurring and to compare the cleaning characteristics of different fouled membranes. A 30-kD molecular weight cutoff polysulfone UF membrane in dead-end mode was challenged with model solutions of tea components. Model solutions consisted of tea proteins, theaflavins (TFs), thearubigins and caffeine. Sodium hydroxide was used as a cleaning reagent. Permeate flux decline curves were presented for single components and mixtures. Individual component transfer fluxes and rejections were also presented. An unexpected finding was that protein in a mixture with TFs could permeate the membrane to a degree, while a protein solution in the absence of the polyphenol was completely rejected. The inspection of membranes fouled by different solutions revealed different foulant morphologies. Membrane cleaning with 0.2 wt % sodium hydroxide was generally found to be effective. [source]


    A BATCH CULTURE METHOD FOR MICROALGAE AND CYANOBACTERIA WITH CO2 SUPPLY THROUGH POLYETHYLENE MEMBRANES,

    JOURNAL OF PHYCOLOGY, Issue 4 2010
    Yvonne Pörs
    A new method for CO2 supply to photoautotrophic organisms was developed, and its applicability for measuring specific growth rates in shaken batch cultures of cyanobacteria and unicellular algae was shown. Small bags containing a concentrated carbonate buffer with a CO2 partial pressure of 32 mbar were prepared from a thin foil of low density polyethylene (LDPE). These bags were inserted as CO2 reservoirs (CRs) into polystyrene culture flasks with gas-permeable screw caps, which were suitable to photometric growth measurement. CO2 was released directly into the medium with membrane-controlled kinetics. The CRs were not depleted within 1 week, although the atmosphere in the culture vessel exchanged rapidly with the ambient air. Rates of initial growth and final densities of the cultures of six different unicellular algal species and one cyanobacterium were markedly increased by diffusive CO2 supply from the CR. In the presence of a CR, growth was exponential during the first 2 d in all cultures studied. The method described allowed a high number of measurements of specific growth rates with relatively simple experimental setup. [source]


    RAPID EFFECT OF PROGESTERONE ON TRANSEPITHELIAL RESISTANCE OF HUMAN FETAL MEMBRANES: EVIDENCE FOR NON-GENOMIC ACTION

    CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 2 2008
    CH Verikouki
    SUMMARY 1The factors that regulate human fetal membrane transport mechanisms are unknown. The aim of the present study was to investigate the effect of progesterone on transepithelial electrical resistance (RTE) in the human amniochorion. 2Fetal membranes from uncomplicated term pregnancies were obtained immediately after vaginal or Caesarean deliveries. Intact pieces were mounted as planar sheets separating an Ussing chamber. Progesterone (10,4 to 10,7 mol/L), mifepristone (10,4 to 10,8 mol/L) and combinations of progesterone plus mifepristone were applied to the chambers facing the fetal or maternal sides of the membrane. The RTE was measured before and 1, 5, 10, 15, 20, 25, 30, 45 and 60 min after each solution was added (at 37°C). The RTE was calculated in ,.cm2, according to Ohm's law. 3The mean (±SEM) basal value of RTE before the application of any substance in all experiments was 29.1 ± 0.4 ,.cm2., The net change in the RTE (,RTE) in relation to the basal value was calculated in each experiment. Progesterone, mifepristone and the combination of progesterone and mifepristone induced a rapid, surge-type increase in RTE during the 1st min on both sides of the membrane. The combination of progesterone plus mifepristone exerted a synergistic action. The effect was stronger on the fetal side than on the maternal side for all substances tested (P < 0.05). The highest ,RTE during the 1st min on the fetal side was seen with the combination of progesterone plus mifepristone (4.0 ± 0.3 ,.cm2) and the lowest ,RTE occurred with mifepristone (1.5 ± 0.1 ,.cm2). 4The present results demonstrated that the RTE of human fetal membranes increases rapidly in response to progesterone. It is possible that changes in RTE play a role in the control of membrane permeability during pregnancy. [source]


    5-HT1A RECEPTOR AGONIST PROPERTIES OF ANTIPSYCHOTICS DETERMINED BY [35S]GTP,S BINDING IN RAT HIPPOCAMPAL MEMBRANES

    CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2007
    Yuji Odagaki
    SUMMARY 15-Hydroxytryptamine 1A (5-HT1A) receptors have attracted increasing attention as a promising target for antipsychotic therapy. Although many atypical antipsychotic drugs, including the prototype clozapine, have been reported to be partial agonists at 5-HT1A receptors, these results are often fragmental and derived mainly from experiments that used cultured cells. 2In the present study, [35S]guanosine 5,- O -(3-thiotriphosphate) ([35S]GTP,S) binding assay in rat hippocampal membranes was applied to a series of antipsychotic drugs, especially atypical antipsychotics. 3Most, but not all, of atypical antipsychotic drugs and the classical antipsychotic drug nemonapride behaved as partial agonists at 5-HT1A receptors with varied potencies and relative efficacies. The most potent compound was perospirone with a mean EC50 of 27 nmol/L, followed by aripiprazole (45 nmol/L) > ziprasidone (480 nmol/L) > nemonapride (790 nmol/L) > clozapine (3900 nmol/L) > quetiapine (26 000 nmol/L). The maximal percentage increases over the basal binding (%Emax) for these antipsychotic drugs were 30,50%, with the exception of perospirone (, 15%), whereas 5-HT stimulated the binding to a mean %Emax of 105%. 4Increasing concentrations of the selective and neutral 5-HT1A antagonist WAY100635 shifted the concentration,response curve of nemonapride-stimulated [35S]GTP,S binding to the right and in parallel. 5The relative efficacy or intrinsic activity of a compound was affected differently by the differing concentrations of guanosine diphosphate (GDP) in the assay buffer, which should be taken into consideration when determining the relative efficacies of these antipsychotics as 5-HT1A receptor agonists. 6These results provide important information concerning the relevance of 5-HT1A receptor partial agonist properties in the treatment for schizophrenic patients with most, if not all, of atypical antipsychotic drugs. [source]


    Cor Triatriatum Sinister with and without Left Ventricular Inflow Obstruction: Visualization of the Entire Supravalvular Membrane by Real-time Three-dimensional Echocardiography.

    CONGENITAL HEART DISEASE, Issue 6 2006
    Impact on Clinical Management of Individual Patient
    ABSTRACT We present 4 cases of cor triatriatum in whom the diagnosis was correctly made by 2-dimensional transthoracic echocardiography, which showed the supravalvular left atrial membrane that divides the left atrium into 2 chambers. The pulmonary veins were connected normally to the proximal left atrial chamber and the left atrial appendage was connected to the distal left atrial chamber. In 1 patient there was evidence of severe pulmonary venous obstruction to the mitral valve by Doppler examination, while in the other three, there was no venous obstruction. Patients were then examined by real-time 3-dimensional echocardiography (RT3DE, using ×4 matrix array transducer connected to Sonos 7500 echocardiographic system Phillips, Andover, Mass, USA). This showed the exact morphology of the membrane and led to cancellation of planed surgical intervention in 1 case in which the membrane was only a broad band crossing the left atrial cavity. In addition to delineating the exact morphology of the intracavitary anomaly, this novel echocardiographic imaging modality should be an additive tool to better understand the natural history of these nonobstructive left atrial membranes via longitudinal follow-up of these patients. [source]


    Membrane associated nonmuscle myosin II functions as a motor for actin-based vesicle transport in clam oocyte extracts

    CYTOSKELETON, Issue 10 2007
    Ana S. DePina
    Abstract Nonmuscle myosin II (Myo2) has been shown to associate with membranes of the trans -Golgi network and to be involved in Golgi to ER retrograde protein transport. Here, we provide evidence that Myo2 not only associates with membranes but functions to transport vesicles on actin filaments (AFs). We used extracts from unactivated clam oocytes for these studies. AFs assembled spontaneously in these extracts and myosin-dependent vesicle transport was observed upon activation. In addition, actin bundles formed and moved relative to each other at an average speed of ,0.30 ,m/s. Motion analysis revealed that vesicles moved on the spontaneously assembled AFs at speeds greater than 1 ,m/s. The motor on these vesicles was identified as a member of the nonmuscle Myo2 family based on sequence determination by Edman chemistry. Vesicles in these extracts were purified by sucrose gradient centrifugation and movement was reconstituted in vitro using skeletal muscle actin coated coverslips. When peripheral membrane proteins of vesicles including Myo2 were removed by salt stripping or when extracts were treated with an antibody specific to clam oocyte nonmuscle Myo2, vesicle movement was inhibited. Blebbistatin, a Myo2 specific inhibitor, also blocked vesicle movement. Myo2 light chain kinase activity was found to be essential for vesicle movement and sliding of actin bundles. Together, our data provide direct evidence that nonmuscle Myo2 is involved in actin-dependent vesicle transport in clam oocytes. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source]


    Skin Repair Using a Porcine Collagen I/III Membrane,Vascularization and Epithelization Properties

    DERMATOLOGIC SURGERY, Issue 6 2010
    FALK WEHRHAN MD
    BACKGROUND Collagen membranes have been developed to overcome the problem of limited availability of skin grafts. Vascularization and restricted functional epithelization limit the success of bioartificial constructs. OBJECTIVE To compare the vascularization, epithelization, and integration of a porcine collagen I/III membrane with that of split-thickness skin grafts on skin wounds. MATERIALS AND METHODS In 21 adult pigs, full-thickness skin defects on the rear side of the ear healed by split-thickness skin grafting, by covering with the membrane, or by free granulation. Skin samples on postoperative days 1, 3, 7, 14, 21, and 28 were evaluated histologically (hematoxylin-eosin, Sirius Red) and using immunohistochemistry (cytokeratin 5/6, transforming growth factor beta receptor (TGF,R-III) and immunoblot (TGF,1,3, Smad2/3). Epithelial thickness and TGF,R-III-positive capillary area were quantitatively assessed. RESULTS Epithelization and vascularization in the membrane group were not significantly different from in the group treated with a split-thickness skin graft. Free granulation showed significantly slower epithelization and vascularization (p<.05). TGF,1 and Smad2/3 complex expression were high during free granulation. Matrix was distinguishable until day 7. CONCLUSIONS This membrane serves as a suitable full-thickness dermal substitute, because the membrane is vascularized faster than free granulation tissue and enables early epithelization. Geistlich Biomaterials (Wolhusen, Switzerland) provided the collagen membrane used in this study [source]


    Letter: Lip Grafts,Mucous Membrane and Not Skin

    DERMATOLOGIC SURGERY, Issue 8 2006
    FIACS, LAWRENCE M. FIELD MD
    No abstract is available for this article. [source]


    Reduction of intramembranous particles in the periacrosomal plasma membrane of boar spermatozoa during in vitro capacitation: A statistical study

    DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 3 2000
    Fumie Suzuki-Toyota
    Membrane remodeling in the periacrosomal plasma membrane (PAPM) of boar spermatozoa during incubation in capacitation medium was examined by the freeze-fracture technique. In the preservation medium (PM) group, the major small (about 8 nm) intramembranous particles (IMP) and the minor large (> 10 nm) IMP were distributed evenly in the PAPM. The IMP-free area increased during capacitation. To correct the IMP-free area, arithmetically redistributed (ARD)-IMP density was used for statistical analysis. In the PM group, the mean density ± SD of large IMP was 379 ± 64 and 266 ± 58/,m2, and that of small IMP was 1450 ± 155 and 672 ± 252/,m2 in protoplasmic (P) and external (E) faces, respectively. During capacitation, the significant (P < 0.01) reduction of large IMP density was encountered only in the E face of a few incubation groups, while that of the small IMP density occurred in the P face by 2 h. Consequently, reduction of the total IMP density of both faces was not significant in the large IMP, but it was significant (P < 0.01) in the small IMP. One-fifth of the total small IMP density reduced by 2 h. Filipin-sterol complexes (FSC) were numerous in the PAPM, and FSC-free areas also increased during capacitation. The mechanism of IMP-free area formation and the behavior of the small IMP in the PAPM during capacitation were discussed in relation to membrane stability. [source]


    Electrochemical Elucidation of the Facilitated Ion Transport Across a Bilayer Lipid Membrane in the Presence of Neutral Carrier Compounds

    ELECTROANALYSIS, Issue 11 2010
    Jun Onishi
    Abstract The ion transport facilitated by neutral carrier compounds (valinomycin, nonactin) has been investigated by cyclic voltammetry in the several electrolyte solutions (KF, KCl, KBr, KNO3, KSCN, KClO4), and we demonstrated the effect of the counter anions on the facilitated transport of K+ from the viewpoint of electroneutrality. Voltammograms for the ion transport were generated at steady state and the current density between W1 and W2, jW1,W2, increased with the absolute value of the applied membrane potential, EW1,W2. Then, the magnitude of jW1,W2 at a certain EW1,W2 increased with the hydrophobicity of the counter anion. It was proved that the logarithm of |jW1,W2|at a certain EW1,W2 is almost proportional to the hydration energy of the counter anion. This indicates that not only K+ but also the counter anion distributes into the BLM. Therefore, the magnitude of jW1,W2 at a certain EW1,W2 increased with an increase of pH, because the hydroxide ion was served as a counter anion. Based on the variation of the zero-current potential in case of various asymmetrical ionic compositions, it is found that the amount of cation transport is much larger than that of anion transport. [source]


    Mediated Electron Transfer Across Supported Bilayer Lipid Membrane with TCNQ-Based Organometallic Compounds

    ELECTROANALYSIS, Issue 4 2010
    Meili Qu
    Abstract Supported bilayer lipid membrane (s-BLM) containing one-dimensional compound 1, TCNQ-based (TCNQ=7,7,8,8-tetracyanoquinodimethane) organometallic compound {(Cu2(,-Cl)(,-dppm)2)(,2 -TCNQ)},, was prepared and characterized on the self-assembled monolayer (SAM) of 1-octadecylmercaptan (C18H37SH) deposited onto Au electrode. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results showed that the compound 1, dotted inside s-BLM, can act as mediator for electron transfer across the membrane. Two redox peaks and the charge-transfer resistance of 400,k, were observed for compound 1 inside s-BLM. The mechanism of the electron transfer across s-BLM by TCNQ is by electron hopping while TCNQ-based organometallic compound is by conducting. Further conclusion drawn from this finding is that the TCNQ-based organometallic compound embedded inside s-BLM exhibits excellent electron transfer ability than that of free TCNQ. This opens a new path for the development of s-BLM sensor and/or biosensor by incorporation with TCNQ-based organometallic compounds. [source]


    Voltammetric Investigation of Zinc Release from Metallothioneins Modulated by the Glutathione Redox Couple and Separated with a Porous Membrane

    ELECTROANALYSIS, Issue 20 2008
    Lin Liu
    Abstract Glutathione (GSH), in addition to serving as a redox buffer in cellular environment, has been suggested as a modulator in metal regulation and homeostasis by metallothioneins (MTs). The interactions of MTs with both GSH and its oxidized form GSSG have been shown to govern the direction of metal transfer. Common methods for the determination of zinc release from MTs modulated by GSH/GSSG either involve radioactive species or enzymes or are labor-intensive. In this study, upon separation of Zn2+ from the reaction mixture of MTs and GSH with a centrifugal filter membrane, differential pulse voltammetry (DPV) was used for the Zn2+ quantification. The same approach is extended to the studies of metal transfer between Zn7MT with a GSH/GSSG mixture and that between Zn7MT with GSSG. The concomitant conversion between the free thiol and disulfide bonds was confirmed with UV-vis spectrophotometry. The results demonstrate that GSSG, GSH, and the GSH/GSSG mixture all modulate zinc release from Zn7MT. The percentage of zinc release increases in the order of GSH, GSSG, and the GSH/GSSG mixture. The new approach is demonstrated to be well suited for investigation of redox regulation of MT and its reaction with zinc-containing enzymes. [source]


    Influence of Aprotic Solvent on Selectivity of an Amperometric Sensor with Nafion Membrane

    ELECTROANALYSIS, Issue 5 2006
    B. Chachulski
    Abstract This paper presents the results of investigation on selectivity of the sulfur dioxide amperometric sensor with Nafion membrane in the presence of carbon monoxide and nitrogen dioxide as the interferents. There have been compared selectivity coefficients, for the sensors containing the following internal electrolytes: solution of sulfuric acid (concentration 5,mol dm,3) in pure water (A) and solution of sulfuric acid (concentration 5,mol dm,3) in mixed solvent dimethylsulfoxide-water with an DMSO: H2O mole ratio of 1,:,2 (B). Values of the selectivity coefficients have been calculated based on the calibration curves. Analysis of both calibration curves and selectivity coefficients plays a significant role in optimization of a working point of a particular sensor. The investigated sensor operates in a three-electrode system, where the working and counter electrodes are vacuum sublimation deposited on the membrane surface. [source]


    Amperometry of Heparin Polyion Using a Rotating Disk Electrode Coated with a Plasticized PVC Membrane

    ELECTROANALYSIS, Issue 2 2006
    Jan Langmaier
    Abstract Electrochemical method of detection of heparin polyion was developed based on voltammetry of heparin on a rotating glassy carbon (GC) electrode coated with a plasticized PVC membrane. The membrane was deposited on the GC disk by spin-coating technique using a mixture of solutions of PVC in tetrahydrofuran, and 1,1,-dimethylferrocene (DMFc) and hexadecyltrimethylammonium tetrakis(4-chlorophenyl)borate (HTMATPBCl) in o -nitrophenyl octyl ether. UV/vis reflection spectrometry was used to evaluate the membrane thickness, which exhibits a linear correlation with the membrane resistance measured by impedance spectroscopy. It is shown that this electrode can be used for amperometric or coulometric detection of heparin in aqueous samples of medically relevant concentrations (1,10,U mL,1), with a detection limit of 1.4,U mL,1. Evidence is provided indicating that the current determining step is the reversible adsorption of the ion-pair of heparin polyion with HTMA+ cation at the membrane/aqueous electrolyte interface, which is driven by oxidation of DMFc at the GC/membrane interface. [source]


    Integrated Microanalytical System Coupling Permeation Liquid Membrane and Voltammetry for Trace Metal Speciation.

    ELECTROANALYSIS, Issue 10 2004
    Optimization, Technical Description
    Abstract A new minicell coupling the liquid-liquid extraction technique called permeation liquid membrane (PLM) with an integrated Ir-based Hg-plated microelectrode array for voltammetric detection has been developed for the speciation of heavy metals in natural waters. Lead and cadmium have been used as model compounds. The PLM consists of a carrier (0.1,M 22DD+0.1,M lauric acid) dissolved in 1,:,1 mixture of toluene/phenylhexane held in the small pores (30,nm) of a hydrophobic polypropylene membrane (Celgard 2500). One side of this membrane is in contact with a flowing source solution, containing the metal ions of interest. An acceptor or strip solution (pyrophosphate) is placed on the other side of the PLM with the microelectrode array placed at 480,,m of the PLM. The analyte is transported by the carrier from the source solution to the strip solution. The originality of the new minicell is that accumulation in the strip solution is voltammetrically followed by the integrated microelectrode array in real time, and at low concentration level, using square-wave anodic stripping voltammetry (SWASV). In order to protect the Hg microelectrodes from the adsorption of the hydrophobic carrier, the microelectrodes are embedded in a thin gel layer (280,,m) of 1.5% LGL agarose gel containing 10% of hydrophobic silica particles C18. The choice of optimum conditions is discussed in details in this article. Due to the very small effective strip volume of the new cell (less than 1,,L), high enrichment factor can be obtained (e.g., 330 for Pb) after 2,hours of accumulation. No deaeration of the solutions is required for SWASV measurements. Detection limits under these conditions are 2,pM and 75,pM for Pb and Cd, respectively, using a voltammetric deposition time of 5,min. In addition, no fouling effects were observed with natural water samples. [source]


    Voltammetric Elucidation of Ion Transfer Through an Extremely Thin Membrane

    ELECTROANALYSIS, Issue 9 2004
    Nobuyuki Ichieda
    Abstract Digital simulation of the cyclic voltammogram for the ion transfer through a liquid membrane of thickness from 1,mm to 10,nm was performed. The magnitude of current and the shape of the voltammogram simulated for extremely thin membrane (10,nm thick) were similar to those observed experimentally with a bilayer lipid membrane, BLM, of about 10,nm in thick, when the diffusion coefficient of an ion in the BLM was assumed to be extraordinary small (10,13 to 10,14,cm2 s,1). [source]


    Nanotube Membrane Based Biosensors

    ELECTROANALYSIS, Issue 1-2 2004
    Punit Kohli
    Abstract We review highly sensitive detection based on electrochemical methods. These methods are based on monodisperse gold and alumina nanotubule membranes with inside diameter approaching molecular dimensions. The analyte species can be detected by measuring a change in trans-membrane current when the analyte is added to the nanotubule-based cell. The second method entails the use of a concentration change based on the nanotubule membrane. Biomemtic ion-gated channels micropore and nanotubule membrane sensors are also reviewed. These synthetic ion channels can be switched from an "off" state to an "on" state in response to an external chemical stimulus. Using these methods, we have achieved detection limits as low as 10,pM. Potential applications for these biosensors are in fields such as bioanalytical, biomedical, pharmaceutical and drug discovery. [source]


    Errata: Detection and analysis of protein-protein interactions in organellar and prokaryotic proteomes by native gel electrophoresis: (Membrane) protein complexes and supercomplexes

    ELECTROPHORESIS, Issue 24 2008
    Frank Krause Dr.
    No abstract is available for this article. [source]


    Glucose-Responsive Bioinorganic Nanohybrid Membrane for Self-Regulated Insulin Release

    ADVANCED FUNCTIONAL MATERIALS, Issue 9 2010
    Claudia R. Gordijo
    Abstract A bioinorganic nanohybrid glucose-responsive membrane is developed for self-regulated insulin delivery analogous to a healthy human pancreas. The application of MnO2 nanoparticles as a multifunctional component in a glucose-responsive, protein-based membrane with embedded pH-responsive hydrogel nanoparticles is proposed. The bio-nanohybrid membrane is prepared by crosslinking bovine serum albumin (BSA),MnO2 nanoparticle conjugates with glucose oxidase and catalase in the presence of poly(N -isopropyl acrylamide- co -methacrylic acid) nanoparticles. The preparation and performance of this new nanocomposite material for a glucose-responsive insulin release system is presented. The activity and stability of immobilized glucose oxidase and the morphology and mechanical properties of the membrane are investigated. The enzymatic activity is well preserved in the membranes. The use of MnO2 nanoparticles not only reinforces the mechanical strength and the porous structure of the BSA-based membrane, but enhances the long-term stability of the enzymes. The in vitro release of insulin across the membrane is modulated by changes in glucose concentration mimicking possible fluctuations of blood-glucose level in diabetic patients. A four-fold increase in insulin permeation is observed when the glucose concentration is increased from normal to hyperglycemic levels, which returns to the baseline level when the glucose concentration is reduced to a normal level. [source]


    Ultrafast Photonics: Graphene,Polymer Nanofiber Membrane for Ultrafast Photonics (Adv. Funct.

    ADVANCED FUNCTIONAL MATERIALS, Issue 5 2010
    Mater.
    Loh and co-workers demonstrate on page 782 an electrospun graphene,polymer nanocomposite that exhibits wideband saturable absorbance for laser pulse shaping. A freestanding, mechanically robust membrane which is composed of nanofiber network of graphene-polymer nanocomposite is fabricated by electrospinning and applied as a mode locker in fiber lasers. The performance of these graphene-polymer nanocomposites is better than single-wall carbon nanotubes in terms of modulation depth and nonsaturable loss. [source]


    Graphene,Polymer Nanofiber Membrane for Ultrafast Photonics

    ADVANCED FUNCTIONAL MATERIALS, Issue 5 2010
    Qiaoliang Bao
    Abstract A freestanding membrane composed of a nanofiber network of a graphene,polymer nanocomposite is fabricated by electrospinning and applied as an optical element in fiber lasers. The functionalization of graphene with conjugated organic molecules provides a handle for improving mechanical and thermal properties as well as tuning the optical properties. A small loading (0.07,wt%) of functionalized graphene enhances the total optical absorption of poly(vinyl acetate) (PVAc) by 10 times. The electrospun graphene,polymer nanocomposites exhibit wideband saturable absorbance for laser pulse shaping, and attain a larger modulation depth and smaller nonsaturable loss than single-walled carbon nanotubes. The results show that electrospun graphene nanocomposites are promising candidates as practical and efficient photonic materials for the generation of ultrashort pulses in fiber lasers. [source]


    High-Performance Multifunctional TiO2 Nanowire Ultrafiltration Membrane with a Hierarchical Layer Structure for Water Treatment

    ADVANCED FUNCTIONAL MATERIALS, Issue 23 2009
    Xiwang Zhang
    Abstract A novel, multifunctional TiO2 nanowire ultrafiltration (UF) membrane with a layered hierarchical structure is made via alkaline hydrothermal synthesis, followed by a filtration and hot-press process. The TiO2 UF membrane has high surface porosity (21.3%) and pore size values around 20,nm. The membrane possesses multifunctional capabilities under UV irradiation, such as anti-fouling, anti-bacterial, concurrent separation, and photocatalytic oxidation. The unique properties of the membrane indicate its potential in applications for environmental purification. [source]


    Inside Front Cover: Novel Engineered Ion Channel Provides Controllable Ion Permeability for Polyelectrolyte Microcapsules Coated with a Lipid Membrane (Adv. Funct.

    ADVANCED FUNCTIONAL MATERIALS, Issue 2 2009
    Mater.
    In their Full Paper on page 201, Donald Martin and co-workers describe the covering of polyelectrolyte microcapsules with a lipid bilayer that incorporates a novel engineered ion channel to provide a functional capability to control transport across the microcapsule wall. The cover image shows atomic-force microscopy images of these 8-layer polyelectroctrolyte capsules recorded using tapping mode in an aqueous environment. The capsules can be seen to collapse in a folded manner, with an occasional wrinkle that "absorbs" the extra surface area when flattening the spherical surface. [source]


    Novel Engineered Ion Channel Provides Controllable Ion Permeability for Polyelectrolyte Microcapsules Coated with a Lipid Membrane

    ADVANCED FUNCTIONAL MATERIALS, Issue 2 2009
    Andrew R. Battle
    Abstract The development of nanostructured microcapsules based on a biomimetic lipid bilayer membrane (BLM) coating of poly(sodium styrenesulfonate) (PSS)/poly(allylamine hydrochloride) (PAH) polyelectrolyte hollow microcapsules is reported. A novel engineered ion channel, gramicidin (bis-gA), incorporated into the lipid membrane coating provides a functional capability to control transport across the microcapsule wall. The microcapsules provide transport and permeation for drug-analog neutral species, as well as positively and negatively charged ionic species. This controlled transport can be tuned for selective release biomimetically by controlling the gating of incorporated bis-gA ion channels. This system provides a platform for the creation of "smart" biomimetic delivery vessels for the effective and selective therapeutic delivery and targeting of drugs. [source]


    A Thermoresponsive Membrane for Chiral Resolution,

    ADVANCED FUNCTIONAL MATERIALS, Issue 4 2008
    Mei Yang
    Abstract A novel thermoresponsive membrane for chiral resolution with high performance has been developed. The membrane exhibits chiral selectivity based on molecular recognition of beta-cyclodextrin (, -CD) and thermosensitivity based on the phase transition of poly(N -isopropylacrylamide) (PNIPAM). Linear PNIPAM chains were grafted onto porous nylon-6 membrane substrates by using a plasma-graft pore-filling polymerization method; the chains thus acted as microenvironmental adjustors for , -CD molecules. , -CD moieties were introduced into the linear PNIPAM chains by a chemical grafting polymerization method and acted as chiral selectors. The phase transition of grafted PNIPAM chains affects the microenvironment of , -CD molecules and, thus, the association between , -CD and guest molecules. The chiral selectivity of the prepared thermoresponsive membranes in chiral resolution operated at temperature below the lower critical solution temperature (LCST) of PNIPAM is higher than that of membranes with no thermosensitivity. Furthermore, the decomplexation ratio of enantiomer-loaded thermoresponsive membranes in decomplexation at temperatures above the LCST is much higher than that of membranes with no thermosensitivity. Thus, by simply changing the operation temperature, high, selective chiral resolution and efficient membrane regeneration are achieved. The proposed membrane provides a new and efficient way to solve the difficult decomplexation problem of chiral solid membranes, which is highly attractive for chiral resolution. [source]


    Drug,Membrane Interaction on Immobilized Liposome Chromatography Compared to Immobilized Artificial Membrane (IAM), Liposome/Water, and Octan-1-ol/Water Systems

    HELVETICA CHIMICA ACTA, Issue 2 2010
    Xiangli Liu
    Abstract The objective of this study was to investigate drug,membrane interaction by immobilized liposome chromatography (ILC; expressed as lipophilicity index log,Ks) and the comparison with lipophilicity indices obtained by liposome/H2O, octan-1-ol/H2O, and immobilized artificial membrane (IAM) systems. A set of structurally diverse monofunctional compounds and drugs (nonsteroidal anti-inflammatory drugs and , -blockers) were selected in this study. This set of solutes consists of basic or acidic functionalities which are positively or negatively charged at physiological pH,7.4. No correlation was found between log,Ks from ILC and lipophilicity indices from any of the other membrane model systems for the whole set of compounds. For structurally related compounds, significant correlations could be established between log,Ks from ILC and lipophilicity indices from IAM chromatography and octan-1-ol/H2O. However, ILC and liposome/H2O systems only yield parallel partitioning information for structurally related large molecules. For hydrophilic compounds, the balance between electrostatic and hydrophobic interactions dominating drug partitioning is different in these two systems. [source]


    Self-Assembled Free-Standing Graphite Oxide Membrane

    ADVANCED MATERIALS, Issue 35 2009
    Chengmeng Chen
    No abstract is available for this article. [source]


    Self-Assembled Free-Standing Graphite Oxide Membrane

    ADVANCED MATERIALS, Issue 29 2009
    Chengmeng Chen
    Flexible, semi-transparent, and free-standing graphite oxide membranes are produced by a facile self-assembly process at the liquid/air interface, and the membranes are thickness controlled and area adjustable. Such macroscopic membranes are constructed from individual graphene oxide sheets by layer-by-layer stacking and show excellent mechanical and optical performance. [source]


    Dip-Pen Nanolithography of Bioactive Peptides on Collagen-Terminated Retinal Membrane,

    ADVANCED MATERIALS, Issue 19 2008
    Rizaldi Sistiabudi
    Dip-pen nanolithography is used to directly modify freshly dissected eye tissues with biologically active collagen-binding peptide molecules. The results address the challenge of surface heterogeneity and utilize dip-pen nanolithography to control the localization and concentration of molecules on a collagen-terminated tissue-derived surface. This method can allow the development of scaffolds for treatment of age-related macular degeneration. [source]