Mosaic Membrane Research Articles

Novel method to prepare charged mosaic membrane by using dipole-like microspheres. I. Preparation and characterization of poly(4-vinylpyridine/n-butyl acrylate) seed latex with high solid content by soap-free emulsion polymerization

The stable latex of poly(4-vinylpyridine-co-n-butyl acrylate) (P4VP/nBA) with a solid content as high as 10 wt % was prepared by a modified soap-free emulsion polymerization. A mixture of water and organic solvents was employed as the continuous phase for increasing the solid content of the latex. Several organic solvents were investigated and, among them, ethyl acetate (EA) and diethyl ether (DE) were effective. The stable latex with 10 wt % solid content was prepared by charging 10 wt % EA or a EA/DE mixture (5 wt % each); however, more than 10 wt % solid content of the stable latex could not be obtained even by charging more than 10 wt % EA or a EA/DE mixture. The stable latex with 10 wt % solid content, which was crosslinked with less than 0.5 wt % (based on monomer) of ethylene glycol dimethacrylate, was prepared by charging 10 wt % of EA. In this case, however, the pH of the continuous phase had to be adjusted to lower than 4. The effects of EA on the characteristics of the resulting uncrosslinked latex were investigated by employing ζ-potential measurements and scanning electron microscopy. It was found that the mass of coagulum decreased as the EA increased. At 8 wt % of EA, a stable latex of 10 wt % solid content without any coagulum was obtained. The ζ potential of particles increased from −100 up to 45.7 mV as the EA increased from 0 to 10 wt %. The effects of batch and semicontinuous copolymerization on the morphology of the microspheres were investigated by using DSC and ultrathin cross-sectional transmission electron miscroscopy photos. A core–shell structure was not found, despite the batch copolymerization of 4VP(1)/nBA(2) (r1 = 4.3, r2 = 0.23), even with disparate reactivity ratios. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1731–1740, 2000

Charged mosaic membrane prepared from microsphere gel and its characterization

A charged mosaic membrane with parallel array of different negative and positive charges was prepared from microsphere gel. Several characteristics on the novel membrane were investigated through experiments concerning transport studies, membrane potentials and membrane resistance. From analysis of the volume flux and salt flux, preferential salt transport across the charged mosaic membrane was suggested. Membrane potential did not indicate a constant value and the absolute value decreased rapidly in short time. The large time dependence supported the interpretation on salt flow in transport studies. From potential measurement, cationic and anionic transport numbers in membrane also were determined to t ̄ K + =0.41 and t ̄ Cl − =0.59. Membrane resistance of this mosaic membrane indicated slightly higher values than that of ordinary charged membrane.

Novel method to prepare charged mosaic membrane by using dipole-like microspheres. I. Preparation and characterization of poly(4-vinylpyridine/n-butyl acrylate) seed latex with high solid content by soap-free emulsion polymerization

The stable latex of poly(4-vinylpyridine-co-n-butyl acrylate) (P4VP/nBA) with a solid content as high as 10 wt % was prepared by a modified soap-free emulsion polymerization. A mixture of water and organic solvents was employed as the continuous phase for increasing the solid content of the latex. Several organic solvents were investigated and, among them, ethyl acetate (EA) and diethyl ether (DE) were effective. The stable latex with 10 wt % solid content was prepared by charging 10 wt % EA or a EA/DE mixture (5 wt % each); however, more than 10 wt % solid content of the stable latex could not be obtained even by charging more than 10 wt % EA or a EA/DE mixture. The stable latex with 10 wt % solid content, which was crosslinked with less than 0.5 wt % (based on monomer) of ethylene glycol dimethacrylate, was prepared by charging 10 wt % of EA. In this case, however, the pH of the continuous phase had to be adjusted to lower than 4. The effects of EA on the characteristics of the resulting uncrosslinked latex were investigated by employing ζ-potential measurements and scanning electron microscopy. It was found that the mass of coagulum decreased as the EA increased. At 8 wt % of EA, a stable latex of 10 wt % solid content without any coagulum was obtained. The ζ potential of particles increased from −100 up to 45.7 mV as the EA increased from 0 to 10 wt %. The effects of batch and semicontinuous copolymerization on the morphology of the microspheres were investigated by using DSC and ultrathin cross-sectional transmission electron miscroscopy photos. A core–shell structure was not found, despite the batch copolymerization of 4VP(1)/nBA(2) (r1 = 4.3, r2 = 0.23), even with disparate reactivity ratios. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1731–1740, 2000

Two-dimensional receptor patterns in the plasma membrane of cells. A critical evaluation of their identification, origin and information content

A concise review is presented on the nature, possible origin and functional significance of cell surface receptor patterns in the plasma membrane of lymphoid cells. A special emphasize has been laid on the available methodological approaches, their individual virtues and sources of errors. Fluorescence energy transfer is one of the oldest available means for studying non-randomized co-distribution patterns of cell surface receptors. A detailed and critical description is given on the generation of two-dimensional cell surface receptor patterns based on pair-wise energy transfer measurements. A second hierarchical-level of receptor clusters have been described by electron and scanning force microscopies after immuno-gold-labeling of distinct receptor kinds. The origin of these receptor islands at a nanometer scale and island groups at a higher hierarchical (μm) level, has been explained mostly by detergent insoluble glycolipid-enriched complexes known as rafts, or detergent insoluble glycolipids (DIGs). These rafts are the most-likely organizational forces behind at least some kind of receptor clustering [K. Simons et al., Nature 387 (1997) 569]. These models, which have great significance in trans-membrane signaling and intra-membrane and intracellular trafficking, are accentuating the necessity to revisit the Singer–Nicolson fluid mosaic membrane model and substitute the free protein diffusion with a restricted diffusion concept [S.J. Singer et al., Science 175 (1972) 720].

10] Ion channels as tools to monitor lipid bilayer-membrane protein interactions: Gramicidin channels as molecular force transducers

Publisher Summary Numerous studies show that membrane protein function depends on the bilayer lipid composition. Specifically, the function of integral membrane proteins varies with lipid bilayer thickness and monolayer equilibrium curvature. In most cases, there is only modest chemical specificity in these membrane lipid-protein interactions. This lack of chemical specificity, together with the large number of lipid types that are found in the membranes of any given cell, has caused difficulties for attempts to understand the way the function of integral membrane proteins is affected by the bilayer lipid composition. These difficulties arose in part because the results were interpreted within the framework of the Singer-Nicolson fluid mosaic membrane model. A weakness of the fluid mosaic membrane model was that the lipid bilayer component was assumed to be a passive entity only—that is, a permeability barrier that separated the extracellular and intracellular aqueous phases. The view of the lipid bilayer as a sheet of liquid hydrocarbon led to the notion of bilayer fluidity as an important determinant of protein function. An important, but neglected consequence of the liquid-crystalline organization of lipid bilayers is that one needs to incorporate the bilayer material properties (thickness and compression modulus, curvature and bending modulus) into a description of membrane protein organization and function. Similarly, one needs to consider specifically the importance of geometric packing criteria for lipid-protein interactions and protein function.

電荷を有した膜中におけるイオンの輸送 正・負荷電基をもつ複合膜を介したイオン透過

Studies on composite membrane with two different kinds of charged groups were reviewed. The composite membranes with parallel and series arrangement of charges, so-called charged mosaic membrane, and bipolar membrane are promised in potential application such as pressure dialysis or water splitting. The characteristics membrane phenomena correlated with the charge structure were interpreted in terms of cross coefficients in a linear phenomenological equation systematically. It can be stressed that a membrane technology in next step will be developed by such novel membranes.

Supramolecular receptor structures in the plasma membrane of lymphocytes revealed by flow cytometric energy transfer, scanning force- and transmission electron-microscopic analyses

Receptors in the plasma membrane of blood cells in general and in that of lymphocytes in particular are supposed to move around in a random walk fashion relatively freely driven by thermal diffusion, as described by the Singer-Nicolson fluid mosaic membrane model. In this article we summarized data and techniques that indicated nonrandom codistribution patterns of receptor superstructures under conditions, where the generation of such molecular colocalizations by the methods themselves were excluded. Application of fluorescence energy transfer in a flow cytometer helped to analyze such codistribution patterns in cell populations. After normalizing energy transfer values for possible differences between labeling ratios of the targeting monoclonal antibodies and using the mean values of energy transfer distribution curves, two-dimensional receptor maps were generated from data obtained in a pair-wise fashion between receptors. Major histocompatibility complex (MHC) class I and II, intercellular adhesion molecule-1 (ICAM-1), TcR-CD3-CD4, tetraspan molecules (CD81, CD82, CD53), and the subunits of the multisubunit IL-2 receptor displayed nonrandom codistribution patterns sometimes with, but very frequently without induction by their ligand. Immunogold-bead "sandwich" labeling analyzed by atomic force microscopy has shown that such receptor "islands" existed also in "receptor-island-groups". This indicated the existence of nonrandom receptor distribution of MHC class I and II molecules also at an elevated hierarchical level. An analysis is given herein concerning a standardized approach. The apparent incompatibility of these supramolecular patterns with the Singer-Nicolson type "free-protein and lipid-mobility paradigm" was resolved by recommending an additional emphasis on the mosaicism of the membrane besides receptor mobility.

Three Big Hands-On Noncomputer Models for the Biology Classroom

Research Article| January 01 1998 Three Big Hands-On Noncomputer Models for the Biology Classroom James E. Miller James E. Miller Search for other works by this author on: This Site PubMed Google Scholar The American Biology Teacher (1998) 60 (1): 52–53. https://doi.org/10.2307/4450413 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation James E. Miller; Three Big Hands-On Noncomputer Models for the Biology Classroom. The American Biology Teacher 1 January 1998; 60 (1): 52–53. doi: https://doi.org/10.2307/4450413 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentThe American Biology Teacher Search This content is only available via PDF. Copyright 1998 The National Association of Biology Teachers Article PDF first page preview Close Modal You do not currently have access to this content.

Transport Behavior of Electrolytes Through Charged Mosaic Composite Membranes

Abstract The first part of this article reviews the strong acid/strong base type charged mosaic composite membrane. A template pattern with alternating poly(4-vinylpvridine) (P4VP)/poly(vinyl alcohol) (PVA) lamellae was fabricated upon a microporous membrane by casting of poly[4-vinylpyridine (4VP)-g-vinyl alcohol (VA)] graft copolymer from a water/l-propanol mixture. After a treatment involving the binding of the microporous membrane with the graft copolymer and also domain fixing of the PVA phases, a dilute solution of poly[sodium p-styrenesulfonate (SSS)-g-VA] graft co-polymer/P4VP binary blend was cast on this template surface. After chemical treatments (introduction of a positive charge and domain fixing of ion-exchange regions), we examined the transport of KCl and selective transport of a KCl-sucrose mixture through the charged mosaic composite membrane. The second section reviews the weak acid strong base type charged mosaic composite membrane. In this type, the charged mosaic regions were compose...

Microstructure of charged mosaic membranes constructed by phase growth

AbstractA template pattern with alternating poly(4‐vinylpyridine) (P4VP)/poly(vinyl alcohol) (PVA) lamellae was fabricated upon a cross‐linked PVA film by casting of poly[4‐vinyl‐pyridine (4VP)‐g‐vinyl alcohol (VA)] graft copolymer. After a treatment involving the binding of a PVA film with the graft copolymer and also domain fixing of the PVA phases, a dilute solution of poly[acrylic acid (AA)‐benzyl N,N‐dimethyldithiocarbamate (DMTC)] copolymer/P4VP binary blend was cast on this template surface. The microstructure of binary blend was observed from scanning electron microscopy (SEM) by wet‐etching of films after domain fixing of one component of the binary blend. The poly(AA‐DMTC) copolymer/P4VP binary microdomains formed by phase growth were oriented perpendicularly to the film surface. We also fabricated these charged mosaic regions on a microporous poly(vinyl chloride) (PVC) membrane, and carried out the surface analysis by X‐ray photoelectron microscopy (XPS). Finally, we examined the transport of KCl through the charged mosaic composite membranes. © 1994 John Wiley & Sons, Inc.

X-ray diffraction on biomembranes with emphasis on lipid moiety.

The theme of the fluid mosaic membrane by Singer and Nicholson (1972), in any colored variation, is known to every student of the biosciences. Yet, there exists no complete picture of the structure and dynamics of any real biological membrane, based on a sufficient set of experimentally determined atomic coordinates and trajectories. While the paradigm of static structure as a determinant of biological function has proven extremely fruitful for nucleic acids, and to a large extent also for proteins, this seems not to be the case with biological membranes. From all we know today, the static structures and mechanistic interactions are necessary to describe the protein moiety of membranes; this could be sufficiently defined in terms of three-dimensional atomic coordinates and their dislocations on conformational changes. However, a major species of membranes constituents, the lipids, appears to be physiologically in a state of dynamic disorder within certain limits given by the overall morphology—planar, tubular, or micellar—of the membrane. This is related to the situation in liquid crystals (De Gennes, 1974), and the physical description of membrane lipids has greatly benefited from the phenomenology applied to that field.KeywordsSynchrotron RadiationElectron Density ProfileLipid Phase TransitionLipid Model MembraneHydrocarbon Chain PackingThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Electron Transport and Redox Chain Reactions in a Mosaic Membrane

Abstract A circulating current enhances transports of ions and electrons in a mosaic membrane system with ion-exchange membranes and electron-transport membranes. Electron transport is readily coupled to ion transport in a new mosaic membrane with electron-transport regions and ion-exchange regions. Electrons and ions are transported in the same or opposite direction by the driving forces of the redox potential gradient or the concentration gradient. Redox chain reactions are also generated in the mosaic membrane system as the electron flow in biological membranes.

Interpenetrating polymer network films as piezodialysis membranes

AbstractIn the present study, interpenetrating polymer network (IPN) membranes were investigated for their potential application as piezodialysis membranes. These IPN membranes are not mosaic membranes. It was found that some of these membranes did show piezodialysis effects. Two of the membranes tested under high pressure gave permeates which were found to be more concentrated in sodium chloride than the initial feed solution, when analyzed by differential refractometry. The permeates from one membrane were double checked by titrating the chloride ion with silver nitrate solution. The results of the titration also indicated a positive effect.

Neutralized surfactant pair domains in positively charged vesicles: modeling of proposed mosaic membrane organization

La cosonication du bromure de dioctadecyldimethylammonium et [CH 2 =CHC 6 H 4 CONH(CH 2 ) 11 O] [n-C 16 H 33 O] PO 2 − conduit a la formation de vesicules

Heterogeneity of membrane transport quantified by the analysis of a unidirectional flux transient of charged tracer

A planar mosaic membrane consists of patches, each with a given area, diffusion coefficient, and mobility of charged tracer; a common electric field, constant in space and time, lies across all the patches. Given the properties of the patches, the transient of the total unidirectional flux (summed over the patches) is predictable. Here we deal with the inverse problem: Given only the observed transient of the total unidirectional flux (as defined experimentally by Ussing), the unknown transport heterogeneity of the mosaic membrane is to be analyzed. Results obtained previously for uncharged tracers are generalized to include effects of the field. In particular, the ratio of the arithmetic and harmonic means (both area-weighted) of the diffusion coefficients, evaluated over the membrane, is expressed in terms of only the observed transient and the field strength and is used to characterize the heterogeneity; and the unique exact solution of the inverse problem for two kinds of patches is recovered at any field strength. If the mosaic consists of n distinct kinds of patches, a sweep of the field strength from low to high values reveals (at most) n steplike shapes in the time course of the total unidirectional flux (normalized to its final steady value), which permit an approximate analysis of the heterogeneity by elementary means.

Synthesis and properties of 4‐vinyl pyridine grafted SBS used as charged mosaic membrane

AbstractThe grafting of 4‐vinyl pyridine onto styrene‐butadiene‐styrene triblock copolymer by irradiation was studied. Cationic and anionic groups were introduced by sulfonation and methylation to obtain a charged mosaic membrane.The experiments showed an increased rate of grafting with the increase of irradation dose. The best concentration of monomer was at 20%.After grafting, the contact angle and the water content were tested and morphology studies were performed.Furthermore, the tensile strength of this membrane increased with increased percentage of grafting. After testing, the charged mosaic membrane had a reduced potential. Its anionic and cationic exchange capacitites were between 0.12 to 0.13 meq/g, and 0.24 to 0.343 meq/g, respectively. The ratio of exchanged capacity was up to 0.509. KCI and urea can be separated by dialysis. In the determination of a piezodialysis, the salt enrichment reached a percentage of 10.3.

Selective Piezodialysis by Crown Ether Mosaic Membrane

Abstract Piezodialysis behavior of mosaic membrane containing dibenzo-18-crown-6 structure was investigated. Depending on the ion exchange selectivity and the difference of hydration degree, selective piezodialysis behavior for alkali metal ions was obtained.

Preparation and characterization of 4-vinyl pyridine-grafted SBS triblock copolymer

Study on the graft of 4-vinyl pyridine to styrene-butadiene-styrene triblock copolymer by solution polymerization shows that the catalyst concentration, temperature, and reaction time are the major influencing factors. Graft efficiency increases with temperature and time but levels off when temperature is higher than 65°C. Increasing concentration of catalyst also promotes graft, but when it is higher than 1.0 × 10−2M, the reaction system begins to gel. A cast film of the graft copolymer was dried, cross-linked with S2Cl2 in nitromethane solution, sulfonated, and chloromethylated. The water content of the membrane is 13.5%. Its anionic and cationic exchange capacities are 0.066 mEq per dry gram and 0.273 mEq per dry gram, respectively. The anionic-cationic capacity ratio is thus 0.26. The nitrogen content of the graft copolymers was determined with a CHN elemental analyzer, and qualitative analysis was carried out with infrared spectroscopy. Transmitting electronic microscopy was used to study the morphology and feasibility of preparing a charged mosaic membrane for piezodialysis.

Charge mosaic membranes: Microdomain fixing of (polystyrene–poly‐4‐vinylpyridine) sequential copolymers prepared by macromonomer methods

AbstractPolystyrene (PST) macromonomers having several allyl groups at the ends were synthesized by the mechanical scission reaction of the main chain in the presence of diallylmalonic acid diethyl ester (DAME). Photosensitive benzophenone groups were introduced on a PST macromonomer molecule by the reaction of these PST macromonomers with benzoyl chloride. The palm‐treelike (PST–poly‐4‐vinylpyridine (P4VP)) sequential copolymers with different compositions were prepared by the radical copolymerization of PST macromonomer with 4VP. The morphological observation of these sequential copolymers was carried out by the transmission electron microscopy. The PST block microdomains were fixed by photocrosslinks (UV irradiation) in the presence of mono‐ and bifunctional unsaturated compounds in the state of mesomorphic structures. The microdomain fixing of P4VP blocks was carried out by using the vapor of 1, 4‐dibromobutane (DBB). After subsequent chemical modifications (quaternization of residual P4VP blocks and sulfonation of PST blocks), the effect of microdomain fixings was elucidated from the moisture content of positive and negative regions. These results are discussed in some detail.

Fluid mosaic membranes and the light reactions of photosynthesis

Fluid mosaic membranes and the light reactions of photosynthesis