Crosslinked poly(ethylene oxide) fouling resistant coating materials for oil/water separation

Potential fouling reducing coating materials were synthesized via free-radical photopolymerization of aqueous solutions of poly(ethylene glycol) diacrylate (PEGDA). Crosslinked PEGDA (XLPEGDA) exhibited high water permeability and good fouling resistance to oil/water mixtures. Water permeability increased strongly with increasing the water content in the prepolymerization water mixture, going from 10 to 150 L μm/(m² h bar) as prepolymerization water content increased from 60 to 80 wt.%. However, molecular weight cutoff decreased as water content increased. These materials were applied to polysulfone (PSF) UF membranes to form coatings on the surface of the PSF membranes. Oil/water crossflow filtration experiments showed that the coated PSF membranes had water flux values 400% higher than that of an uncoated PSF membrane after 24 h of operation, and the coated membranes had higher organic rejection than the uncoated membranes.     

Hydrophilic composite elastomeric mold for high-resolution soft lithography

Here, we introduce a nanopatternable hydrophilic composite elastomer highly desirable for both nanostructure patterning via solvent-assisted micromolding (SAMIM) and microcontact printing of polar inks. This composite precursor is prepared by blending two UV-curable materials, Norland Optical Adhesives (NOA) 63 and poly(ethylene glycol) diacrylate (PEGDA), in an appropriate ratio; upon UV polymerization, a nanopatternable elastomer with preferential permeability both to aqueous and organic solvent is fabricated. Using this composite mold, nanoscale SAMIM of poly(4-vinylpyridine) (P4VP) and microcontact printing of a polar biomolecule, bovine serum albumin (BSA), was successfully demonstrated, paving the way for facile and efficient reproduction of various nanopatterns and a biomolecule-printed array platform.     

Transport properties of small molecules in zwitterionic polymers

Despite great interests in using zwitterionic polymers for membrane surface modification to enhance antifouling properties, there lacks fundamental understanding of the relationship between polymer structure and water/salt separation properties. In this study, two series of zwitterionic polymers were prepared from sulfobetaine methacrylate and 2‐methacryloyloxyethyl phosphorylcholine. Both are crosslinked by poly(ethylene glycol) diacrylate (PEGDA). These copolymers were thoroughly characterized in terms of sol‐gel fraction, density, glass transition temperature, contact angle, water and salt transport properties, and pure‐gas permeability. Interestingly, the zwitterionic polymers exhibit water sorption and permeability similar to noncharged poly(ethylene glycol)‐based materials. These zwitterionic polymers exhibit lower NaCl diffusivity and permeability and thus higher water/NaCl selectivity than the non‐charged PEG‐based materials at similar water volume fractions, demonstrating their promise for membrane surface modification for desalination and wastewater treatment. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1924–1934     

Effects of sensitizer length on radiation crosslinked shape–memory polymers

Shape–memory polymers (SMPs) are smart materials that can be designed to retain a metastable state and upon activation, recover a preprogrammed shape. In this study, poly(methyl acrylate) (PMA) is blended with poly(ethylene glycol) diacrylate (PEGDA) of various molecular weights in various concentrations and subsequently exposed to ionizing radiation. PEGDA sensitizes the radiation crosslinking of PMA, lowering the minimum absorbed dose for gelation and increasing the rubbery modulus, after crosslinking. Minimum dose for gelation, as determined by the Charlesby–Pinner equation, decreases from 25.57 kGy for unblended PMA to 2.06 kGy for PMA blended with 10.00 mole% PEGDA. Moreover, increase in the blend concentration of PEGDA increases the crosslinking density of the resulting networks. Sensitizer length, namely M_n of PEGDA, also affects crosslinking and final mechanical properties. Increase in the length of the PEGDA molecule at a constant molar ratio increases the efficacy of the molecule as a radiation sensitizer as determined by the increase in gel fraction and rubbery modulus across doses. However, at a constant weight ratio of PEGDA to PMA, shorter PEGDA chains sensitize more crosslinking because they have more reactive ends per weight fraction. Sensitized samples of PMA with PEGDA were tested for shape–memory properties and showed shape fixity of greater than 99%. Samples had a glass transition temperature near 28 °C and recovered between 97% and 99% of the induced strain when strained to 50%.     

Multilayer transfer printing on microreservoir-patterned substrate employing hydrophilic composite mold for selective immobilization of biomolecules

In this study, we introduce a hydrophilic composite mold with elasticity and moderate water permeability, suitable for transferring water-soluble polar molecules such as polyelectrolyte multilayer. This composite mold is constructed from two UV-curable polymers-Norland Optical Adhesives (NOA) 63, a urethane-related polymer, and poly(ethylene glycol) diacrylate (PEGDA). The mixture of inherently hard NOA 63 and hydrogel precursor, PEGDA, resulted in an optically transparent mold with some degree of elasticity and enhanced water permeability upon UV polymerization. Employing the NOA 63-PEGDA composite mold, a polyelectrolyte multilayer comprising alternate thin layers of poly(acrylic acid) (PAA) and poly(acrylamide) (PAAm) was transfer-printed onto arrays of microreservoir-patterned substrate to selectively prevent unwanted adsorption of biomolecules on the protruding surface. Antibody was immobilized selectively inside the microreservoirs where multilayer was not transferred, and a specific antibody binding reaction was detected inside the microreservoirs. Furthermore, the potential of this composite mold as a convenient tool for constructing a biosensor for detecting Escherichia coli (E. coli) O157:H7 was explored.     

The effect of crosslinked networks with poly(ethylene glycol) on sulfonated polyimide for polymer electrolyte membrane fuel cell

To investigate the effect of crosslinking by a hydrophilic group on a sulfonated polyimide electrolyte membrane, sulfonated polyimide end‐capped with maleic anhydride was synthesized using 1,4,5,8‐naphthalenetetracarboxylic dianhydride, 4,4′‐diaminobiphenyl, 2,2′‐disulfonic acid, 2‐bis [4‐(4‐aminophenoxy)phenyl] hexafluropropane and maleic anhydride. The sulfonated polyimides end‐capped with maleic anhydride were self‐crosslinked or crosslinked with poly(ethylene glycol) diacrylate. A series of the crosslinked sulfonated polyimides having various ratios of sulfonated polyimide and poly(ethylene glycol) diacrylate were prepared and compared with uncrosslinked and self‐crosslinked sulfonated polyimides. The synthesized sulfonated polyimide films were characterized for FTIR spectrum, thermal stability, ion exchange capacity, water uptake, hydrolytic stability, morphological structure, and proton conductivity. The formation of sulfonated polyimide was confirmed in FTIR spectrum. Thermal stability was good for all the sulfonated polyimides that exhibited a three‐step degradation pattern. Ion exchange capacity was the same for both the uncrosslinked and the self‐crosslinked sulfonated polyimides (1.30 mEq/g). When the crosslinked sulfonated polyimides with poly(ethylene glycol) were compared, the ion exchange capacity was decreased as 1.27 > 1.25 > 1.23 mEq/g and water uptake was increased as 23.8 < 24.0 < 24.3% with the increase in poly(ethylene glycol) diacrylate content. All the crosslinked sulfonated polyimides with poly(ethylene glycol) diacrylate were stable for over 200 h at 80 °C in deionized water. Morphological structure and mean intermolecular distance were obtained by WAXD. Proton conductivities were measured at 30, 50, 70, and 90 °C. The proton conductivity of the crosslinked sulfonated polyimides with poly(ethylene glycol) diacrylate increased with the increase in poly(ethylene glycol) diacrylate content despite the fact that the ion exchange capacity was decreased. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1455–1464, 2005     

Facile Microfluidic Fabrication of Biocompatible Hydrogel Microspheres in a Novel Microfluidic Device

Poly(ethylene glycol) diacrylate (PEGDA) microgels with tuneable size and porosity find applications as extracellular matrix mimics for tissue-engineering scaffolds, biosensors, and drug carriers. Monodispersed PEGDA microgels were produced by modular droplet microfluidics using the dispersed phase with 49–99 wt% PEGDA, 1 wt% Darocur 2959, and 0–50 wt% water, while the continuous phase was 3.5 wt% silicone-based surfactant dissolved in silicone oil. Pure PEGDA droplets were fully cured within 60 s at the UV light intensity of 75 mW/cm². The droplets with higher water content required more time for curing. Due to oxygen inhibition, the polymerisation started in the droplet centre and advanced towards the edge, leading to a temporary solid core/liquid shell morphology, confirmed by tracking the Brownian motion of fluorescent latex nanoparticles within a droplet. A volumetric shrinkage during polymerisation was 1–4% for pure PEGDA droplets and 20–32% for the droplets containing 10–40 wt% water. The particle volume increased by 36–50% after swelling in deionised water. The surface smoothness and sphericity of the particles decreased with increasing water content in the dispersed phase. The porosity of swollen particles was controlled from 29.7% to 41.6% by changing the water content in the dispersed phase from 10 wt% to 40 wt%.     

Optically clear simultaneous interpenetrating polymer networks based on poly(ethylene glycol) diacrylate and epoxy. I. Preparation and characterization

Poly(ethylene glycol) diacrylate was synthesized from poly(ethylene glycol) of molecular weight 600 with acryloyl chloride in a molar ratio of 1:2. Poly(ethylene glycol) diacrylate (PEGDA) was then blended with diglycidyl ether of bisphenol A (DGEBA) in various ratios, followed by curing with 2,2′-azobisisobutyronitrile (AIBN) and isophronediamine (IPDA) simultaneously. Viscosity changes before and during IPN formation were examined with a Brookfield viscometer. Formation of H-bonding and functional group changes were investigated with FTIR. Exothermic curing thermograms were recorded with dynamic DSC. Optically clear IPNs thus obtained were characterized with rheometric dynamic spectroscopy (RDS) and scanning electron microscopy (SEM) to check possible compatibility of the two networks. Experimental results revealed that during IPN formation hydrogen bonds between PEGDA and DGEBA and interlock of networks had profound effect on viscosity change and pot-life. Complete compatibility of the IPNs was found as DGEBA content was higher than 50% by weight. The compatibility between PEGDA and DGEBA networks was evidenced from inner shift of a single damping peak in RDS. In the meantime, SEM micrographs confirmed the coincidence with the result of RDS © 1992 John Wiley &Sons, Inc.     

The stability of semi-interpenetrating polymer networks based on sulfonated polyimide and poly(ethylene glycol) diacrylate for fuel cell applications

A series of the semi-interpenetrating polymer network (semi-IPN) membranes based on sulfonated polyimide and poly(ethylene glycol) diacrylate were prepared and characterized comparing with pure sulfonated polyimide membrane and commercially available membrane, Nafion^® 117. The proton conductivity increased with the increase of poly(ethylene glycol) diacrylate contents in spite of the decrease in ion exchange capacity which is a key factor to improve the proton conductivity. The water stability of semi-IPN membranes containing poly(ethylene glycol) diacrylate is higher than the pure sulfonated polyimide membrane. Morphological structure showed that amorphous nature of the films also increased with the poly(ethylene glycol) diacrylate contents, which could make a crosslink, so that the crystallinity of polyimide could disappear. Semi-IPN membranes based on sulfonated polyimide and poly(ethylene glycol) diacrylate, which show good conductivity comparable to Nafion^® 117 in the range of 20-50% content of poly(ethylene glycol) diacrylate, could be promising proton conducting membranes in fuel cell application.     

Photopolymerized injectable RGD-modified fumarated poly(ethylene glycol) diglycidyl ether hydrogels for cell growth

In this study, photopolymerized hydrogels of fumarated poly(ethylene glycol) diglycidyl-co- poly(ethylene glycol) diacrylate have been synthesized and modified with cell adhesion peptide, Arg-Gly-Asp (RGD). The structural and mechanical properties of the hydrogels are found to be poly(ethylene glycol) diacrylate (PEGDA) dependent. The percentage of gelation is increased from 72 to 89 wt.-% when the amount of the crosslinker co-monomer (PEGDA) in the hydrogel formulation is increased from 20 to 40 wt.-%. In the present case, the equilibrium mass swelling is decreased from 216 to 93%. The viscosities of the uncured formulations have also been measured and likewise, the results were influenced by the increasing amount of PEGDA that reduced the value from 83 to 36 cP. The compressive modulus of the prepared hydrogels was improved with the addition of the PEGDA. Cell growth experiments have been performed by comparing the properties of the hydrogels with and without RGD units. The results show that RGD units enhance the adhesion of cells to the surface of the hydrogels. SEM-EDS studies reveal that nitrogen and calcium are produced on the osteoblast-seeded surface of the scaffold within the culture time period. [Figure: see text].     

PEGDA/HEMA水凝胶等离子体表面改性的研究

采用紫外光聚合法合成了聚乙二醇双丙烯酸酯(PEGDA)/甲基丙烯酸-2-羟基乙酯(HEMA)复合凝胶,在不同的条件下进行等离子处理后,紫外光下进行表面接枝改性。在凝胶表面引入亲水性基团,改善材料的亲水性。研究了不同等离子体处理条件及辐射条件对丙烯酰胺(AAm)接枝率的影响。研究表明,丙烯酰胺接枝率随着等离子体处理时间的增加先增大后减小,随着紫外光照射时间、丙烯酰胺浓度的增大而增大。     

Monoliths from poly(ethylene glycol) diacrylate and dimethacrylate for capillary hydrophobic interaction chromatography of proteins

Rigid monoliths were synthesized solely from poly(ethylene glycol) diacrylates (PEGDA) or poly(ethylene glycol) dimethacrylates (PEGDMA) containing different ethylene glycol chain lengths by one-step UV-initiated polymerization. Methanol/ethyl ether and cyclohexanol/decanol were used as bi-porogen mixtures for the PEGDA and PEGDMA monoliths, respectively. Effects of PEG chain length, bi-porogen ratio and reaction temperature on monolith morphology and back pressure were investigated. For tri- and tetra-ethylene glycol diacrylates (i.e., PEGDA 258 and PEGDA 302), most combinations of methanol and ethyl ether were effective in forming monoliths, while for diacrylates containing longer chain lengths (i.e., PEGDA 575 and PEGDA 700), polymerization became more sensitive to the bi-porogen ratio. A similar tendency was also observed for PEGDMA monomers. Polymerization of monoliths was conducted at approximately 0 °C and room temperature, which produced significant differences in monolith morphology and permeability. Monoliths prepared from PEGDA 258 were found to provide the best chromatographic performance with respect to peak capacity and resolution in hydrophobic interaction chromatography (HIC). Detailed study of these monoliths demonstrated that chromatographic performance was not affected by changing the ratios of the two porogens, but resulted in almost identical retention times and comparable peak capacities. An optimized PEGDA 258 monolithic column was able to separate proteins using a 20-min elution gradient with a peak capacity of 62. Mass recoveries for test proteins were found to be greater than 90, indicating its excellent biocompatibility. All monoliths demonstrated nearly no swelling or shrinking in different polarity solvents, and most of them could be stored dry, indicating excellent stability due to their highly crosslinked networks. The preparation of these in situ polymerized single-monomer monolithic columns was highly reproducible. The relative standard deviation (RSD) values based on retention times of retained proteins were all within 2.2%, and in most cases, less than 1.2%. The RSD values based on peak areas were within 9.5%, and in most cases, less than 7.0%. The single-monomer synthesis approach clearly improves column-to-column reproducibility.     

Sulfonated Poly(ether ether ketone) and Poly(ethylene glycol) Diacrylate Based Semi-Interpenetrating Network Membranes for Fuel Cells

Polymer electrolyte membranes are prepared from novel semi-interpenetrating polymer network material where the sulfonated poly (ether ether ketone) (SPEEK) is the linear polymer and the poly (ethylene glycol) diacrylate (PEGDA) is the cross-linking constituent. The semi-IPN is prepared by in situ polymerization of PEGDA in the presence of sulfonated poly (ether ether ketone). SPEEK is prepared by direct sulfonation of commercial PEEK (Gatone? 1100) by reported procedures. SPEEK with degree of sulfonation 63% (calculated from FT-NMR) is selected as the base membrane and different semi-IPN membranes were prepared by varying the PEGDA and SPEEK ratio. The degree of sulfonation of SPEEK and the formation of semi-IPN were confirmed by spectroscopy studies. The various semi-IPN membranes were characterized for ion-exchange capacity, water uptake, hydrolytic stability, proton conductivity and thermal stability for evaluating the suitability of these membranes for fuel cells. The proton conductivity of the membranes decreased with increasing PEGDA content. The Semi-IPN membranes exhibited conductivities (30°C) from 0.018 S/cm to 0.006 S/cm. These interpenetrating network membranes showed higher hydrolytic stability than the pure SPEEK membrane. This study shows that semi-IPN membranes based on PEGDA and SPEEK can be viable candidates for electrolyte membranes.     

Surface modification of polydimethylsiloxane with photo-grafted poly(ethylene glycol) for micropatterned protein adsorption and cell adhesion

In this study, we applied photo-induced graft polymerization to micropatterned surface modification of polydimethylsiloxane (PDMS) with poly(ethylene glycol). Two types of monomers, polyethylene glycol monoacrylate (PEGMA) and polyethylene glycol diacrylate (PEGDA), were tested for surface modification of PDMS. Changes in the surface hydrophilicity and surface element composition were characterized by contact angle measurement and electron spectroscopy for chemical analysis. The PEGMA-grafted PDMS surfaces gradually lost their hydrophilicity within two weeks. In contrast, the PEGDA-grafted PDMS surface maintained stable hydrophilic characteristics for more than two months. Micropatterned protein adsorption and micropatterned cell adhesion were successfully demonstrated using PEGDA-micropatterned PDMS surfaces, which were prepared by photo-induced graft polymerization using photomasks. The PEGDA-grafted PDMS exhibited useful characteristics for microfluidic devices (e.g. hydrophilicity, low protein adsorption, and low cell attachment). The technique presented in this study will be useful for surface modification of various research tools and devices.     

Photochemically prepared polysulfone/poly(ethylene glycol) amphiphilic networks and their biomolecule adsorption properties

Polysulfone/poly(ethylene glycol) amphiphilic networks were prepared via in situ photo-induced free radical crosslinking polymerization. First, the hydrophobic polysulfone diacrylate (PSU-DA) oligomer was synthesized by condensation polymerization and subsequent esterification processes. Then, the obtained oligomer was co-crosslinked with the hydrophilic poly(ethylene glycol) diacrylate (PEG-DA) or poly(ethylene glycol) methyl ether acrylate (PEG-MA) at different feed ratios. In the case of PEG-MA, the resulting network possessed dangling pendant hydrophilic chains on the crosslinked surface. The structure and the morphology of the membranes were characterized by attenuated total reflection infrared spectroscopy (ATR-IR) and scanning electron microscopy (SEM). The enhancement of surface hydrophilicity was investigated by water contact angle measurements. The biomolecule adsorption properties of these networks were also studied. The biomolecules easily adsorbed on the surface of the hydrophobic polysulfone networks whereas dangling hydrophilic chains on the surface prevented the adsorption of the biomolecules.     

Preparation of hydrogels by photopolymerization of acrylates in the presence of Type I and one-component Type II photoinitiators

Hydrogels were prepared by photoinduced polymerization of poly(ethylene glycol)monoacrylate (PEGMA) and poly(ethylene glycol)diacrylate (n = 200 and 700) (PEGDA) with Type I, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one (I-2959) and one-component Type II initiators: (9-oxo-9H-thioxanthen-2-yloxy)-acetic acid (TXOCH₂COOH) and (9-oxo-9H-thioxanthen-2-yloxy)-sodium acetate (TXOCH₂COO^?Na⁺). The swelling properties of hydrogels were investigated and observed to be excellent. Smooth morphology and no phase separation were observed from SEM micrographs of the hydrogels.     

Effect of temperature on the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions

In this work the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions were measured at 283.1–313.1 K. The expansion factor of polymer chain was calculated by use of the intrinsic viscosities data. The thermodynamic parameters of polymer solution (the entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer–solvent interaction parameter and second osmotic virial coefficient) were evaluated by temperature dependence of polymer chain expansion factor. The obtained thermodynamic parameters indicate that quality of water was decreased for solutions of poly(ethylene oxide), poly(vinyl pyrrolidone) and poly(ethylene oxide)/poly(vinyl pyrrolidone) blends by increasing temperature. Compatibility of poly(ethylene oxide)/poly(vinyl pyrrolidone) blends were explained in terms of difference between experimental and ideal intrinsic viscosity and solvent–polymer interaction parameter. The results indicate that the poly(ethylene glycol)/poly(vinyl pyrrolidone) blends were incompatible.     

Synthesis of gels by means of Michael addition reaction of multi-functional acetoacetate and diacrylate compounds and their application to ionic conductive gels

Michael-addition reactions of multi-functional acetoacetate, meso-erythritol tetraacetoacetate (ETAA), trimethylolpropane triacetoacetate (TPTAA), and diacrylate compounds, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, or poly(ethylene glycol) diacrylate (PEGDA), in dimethyl sulfoxide have successfully yielded the corresponding gels in the presence of 1,8-diazabicyclo[5.5.0]undecane-7-ene as a catalyst at room temperature. The gel formation rates of the reaction systems with TPTAA were higher than those with ETAA. The gels prepared with the alkyl diacrylate compounds or low molecular weight PEGDA showed higher Young's modulus in compression test. The ETAA-PEGDA gels were also prepared in propylene carbonate containing Li ion or in an ionic liquid. These gels showed good ionic conductivity with conductivity value as high as 2.26 and 2.38 mS/cm at room temperature for the Li ion and ionic liquid containing systems respectively.     

Solubility and partial molar volume of carbon dioxide and ethane in crosslinked poly(ethylene oxide) copolymer

Experimental solubility and sorptive dilation data are reported for carbon dioxide and ethane in a crosslinked poly(ethylene oxide) (XLPEO) rubbery copolymer. Five different temperatures (253 ≤ T(K) ≤ 308) were considered, with a maximum gas pressure of 2.09 MPa (20.6 atm). The polymer was prepared by photopolymerization of a solution containing 70 wt % poly(ethylene glycol) methyl ether acrylate (PEGMEA) and 30 wt % poly(ethylene glycol) diacrylate (PEGDA). Sorption isotherms were described by the Flory‐Huggins model. For each gas, the Flory‐Huggins interaction parameter was a decreasing function of temperature and did not show a composition dependence. Dilation and sorption data were combined to calculate the partial molar volume (PMV) of the gases in the polymer, which was an increasing function of temperature. Based on a comparison with literature data for a XLPEO homopolymer prepared from pure PEGDA over the same range of operating conditions, an effect of the network composition on both gas solubility and PMV was found. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 456–468, 2010     

Hydrogels for in situ encapsulation of biomimetic membrane arrays

Hydrogels are hydrophilic, porous polymer networks that can absorb up to thousands of times their own weight in water. They have many potential applications, one of which is the encapsulation of freestanding black lipid membranes (BLMs) for novel separation technologies or biosensor applications. We investigated gels for in situ encapsulation of multiple BLMs formed across apertures in a hydrophobic ethylene tetrafluoroethylene (ETFE) support. The encapsulation gels consisted of networks of poly(ethylene glycol)‐dimethacrylate or poly(ethylene glycol)‐diacrylate polymerized using either a chemical initiator or a photoinitiator. The hydrogels were studied with regards to volumetric stability, porosity, and water permeability. All hydrogels had pore sizes around 7 nm with volumetric changes >2% upon crosslinking. Photoinitiated hydrogels had a lower hydraulic water permeability compared to chemically initiated hydrogels; however, for all hydrogels the permeability was several‐fold higher than the water permeability of conventional reverse osmosis (RO) membranes. Lifetimes of freestanding BLM arrays in gel precursor solutions were short compared to arrays formed in buffer. However, polymerizing (crosslinking) the gel stabilized the membranes and resulted in BLM arrays that remained intact for days. This is a substantial improvement over lifetimes for freestanding BLM arrays. Optical images of the membranes and single channel activity of incorporated gramicidin ion channels showed that the lipid membranes retained their integrity and functionality after encapsulation with hydrogel. Our results show that hydrogel encapsulation is a potential means to provide stability for biomimetic devices based on functional proteins reconstituted in biomimetic membrane arrays. Copyright © 2010 John Wiley & Sons, Ltd.