Tight Membrane Research Articles

Synthesis, preparation and characterization of UV-cured methacrylated polysulfone-based membranes

A new two-step method involving non-solvent induced phase separation (NIPS) and a UV curing process for the preparation of networked-polysulfone membranes is described. In this approach, first, methacrylated polysulfone macromonomers (PSU-DM)s were prepared by polycondensation followed by end-group esterification. PSU-DMs thin films containing phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) photoinitiator cast on glass plates were successively subjected to NIPS and UV curing processes to produce the ultrafiltration membranes. The reverse sequence, i.e. first UV-curing followed by NIPS was also applied. Although different double bond conversions were attained, both procedures essentially yielded structurally analogous membranes which were insoluble in DMF, DMSO, and boiling water. UV-curing behavior, structure, thermo-mechanical and morphological properties of the membranes were investigated. Regardless of the preparation sequences, membranes exhibited pure water permeability in the range of tight ultrafiltration membranes.

Treatment of an in situ oil sands produced water by polymeric membranes

Cross-flow ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) were applied for the first time on a produced water obtained from a thermal in situ bitumen recovery process called steam-assisted gravity drainage (SAGD), with the intent to remove salt, silica, and dissolved organic matter (DOM) so that the produced water could be re-used as high-quality boiler feedwater. It was found that more hydrophilic and more negatively charged membranes were less susceptible to fouling. The UF membrane tested rejected a maximum of 30% of the salt and silica and 50% of the DOM. Nanofiltration with loose membranes removed more than 70% of the salt and DOM. The tight NF membranes tested removed more than 86% of the salt, silica, and DOM, and consumed less energy than RO, which showed almost the same rejection. An instantaneous increase in water flux resulting from a step change in feedwater pH demonstrated the critical role of pH in flux recovery and in fouling mitigation. Analysis of the fouled membranes indicated presence of silica, iron, and calcium in the foulant material. Feed and permeate characterization showed that mainly hydrophilic DOM passed through the membrane. The study provides valuable insights regarding the suitability of membranes as alternatives to conventional SAGD water treatment methods, especially in terms of producing higher quality recycled water.

Study of the Interface Layer Between Lithium Metal and a Single Ion Conductor Ceramic, Based on Block Copolymer, for Lithium Air Batteries

The electrification of transport is a formidable challenge, however the energy storage possible in Li ion batteries is not sufficient to this purpose. A potential option is Lithium-air battery, first because of their very high energy densities and second because of their low costs. Two different approaches to the development of these batteries are possible: the anhydrous system which uses an organic electrolyte, and the aqueous system which uses an aqueous electrolyte [1]. An advantage of the aqueous system is its safety since toxic or inflammable solvents are not used. In order to protect the negative lithium electrode from the aqueous electrolyte, a thin ceramic water and gas tight membrane is used. The interface between the lithium metal and the ceramic membrane plays an important role in the cycling performance of the aqueous lithium air cell. Nonetheless, the poor or non-chemical stability of most ceramic electrolytes in contact with lithium metal limits the performance. A possible strategy to improve the interface between ceramic electrolyte and lithium metal might be by the use of polymer membranes [2]. This study reports the effect of a polymer membrane between a ceramic electrolyte and lithium metal. Block copolymer electrolytes, such as polystyrene-block-poly (ethylene oxide) copolymer electrolyte (SEO) mixed with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt, were used. The single ion conductor ceramic electrolyte was a Lithium Ion Conducting Glass Ceramic (LICGC) purchased from Ohara Corporation (1 inch X 1 inch 150µm thick). Impedance spectroscopy has been used, so as to study the lithium ion - lithium metal transfer from a lithium ion conducting polymer interface. Furthermore, in order to know if the sandwich polymer-ceramic cell showed an additional interfacial resistance, ionic conductivity experiments using electrochemical impedance spectroscopy were performed. Besides, polarization loss quantification at a lithium ion conducting polymer/single ion conductor interface was studied by DC current measurement by the Srinivasan et al method [3]. Finally, in order to confirm the intimacy of the ceramic and the polymer, the interface between the ceramic and the polymer was studied by synchrotron hard X-Ray micro tomography experiments on symmetric lithium-sandwich polymer-ceramic cells. P.G. Bruce, S. A. Freunberger, L. J. Hardwick, J-M. Tarascon, Nature Materials, 11, 19-29 (2012)G.M. Stone, S.A. Mullin, A.A. Teran, D.T. Hallinan, A.M. Minor, A. Hexemer, N.P. Balsara, Journal of the Electrochemical Society 159(3) A222-A227 (2012)Mehrotra, P. N. Ross, V. Srinivasan, Journal of the Electrochemical Society, 161 (10) A1681-A1690 (2014)

Characterization of hydrophilic nanofiltration and ultrafiltration membranes for groundwater treatment as potable water resources

In this work, two hydrophilic nanofiltration (NF) membranes and a tight ultrafiltration (UF) membrane were studied for drinking water production from groundwater resources. Commercial membranes denoted as TS40, TFC-SR3, and GHSP were selected to investigate their performances. It was found that both NF membranes were hydrophilic with contact angle at 28°and 46°, respectively. The tight UF membrane was hydrophobic at contact angle of 68°. In the permeation test, both NF membranes exhibited higher permeability in pure water (4.68 and 3.99 L m−2 h−1 bar−1) than UF membrane (3.15 L m−2 h−1 bar–1). The order of single salt rejection by NF membranes were identified as R (Na2SO4) > R (MgCl2) > R (NaCl), whereas for UF membrane was R (Na2SO4) > R (NaCl) > R (MgCl2). A primary assessment of groundwater treatment for potable water showed that the highlighted components were characterized mainly by color, turbidity, and total dissolved solid (TDS) at 49 PtCo, 14 NTU, and 25 mg/L, respectively. The NF membrane, especially the TFC-SR3, was more efficient at rejecting these components, in quantities of 3 PtCo of color, 0.2 NTU of turbidity, and 10.5 mg/L of TDS, whereas the UF membrane attained 23 PtCo of color, 1.7 NTU of turbidity, and 17.6 mg/L of TDS. In conclusion, the findings on the quality of treated water verified that hydrophilic NF membrane performed well as a promising new technology for groundwater treatment in Malaysia.

A complex of ZO-1 and the BAR-domain protein TOCA-1 regulates actin assembly at the tight junction.

Assembly and sealing of the tight junction barrier are critically dependent on the perijunctional actin cytoskeleton, yet little is known about physical and functional links between barrier-forming proteins and actin. Here we identify a novel functional complex of the junction scaffolding protein ZO-1 and the F-BAR-domain protein TOCA-1. Using MDCK epithelial cells, we show that an alternative splice of TOCA-1 adds a PDZ-binding motif, which binds ZO-1, targeting TOCA-1 to barrier contacts. This isoform of TOCA-1 recruits the actin nucleation-promoting factor N-WASP to tight junctions. CRISPR-Cas9-mediated knockout of TOCA-1 results in increased paracellular flux and delayed recovery in a calcium switch assay. Knockout of TOCA-1 does not alter FRAP kinetics of GFP ZO-1 or occludin, but longer term (12 h) time-lapse microscopy reveals strikingly decreased tight junction membrane contact dynamics in knockout cells compared with controls. Reexpression of TOCA-1 with, but not without, the PDZ-binding motif rescues both altered flux and membrane contact dynamics. Ultrastructural analysis shows actin accumulation at the adherens junction in TOCA-1-knockout cells but unaltered freeze-fracture fibril morphology. Identification of the ZO-1/TOCA-1 complex provides novel insights into the underappreciated dependence of the barrier on the dynamic nature of cell-to-cell contacts and perijunctional actin.

Clinical significance of serum claudin-7 levels in patients with colorectal cancer.

e14533 Background: Claudin-7 (CLDN7) belongs to the claudin family which consists of 24 subtypes of essential tight junction integral membrane proteins with molecular weights of 20-27 kDa. Tight ju...

Environment-benign preparation of Ag toughening TiO2/Ti tight ultrafiltration membrane via aqueous sol–gel route

A new aqueous sol was synthesized to prepare Ag-doped TiO2/Ti composite tight ultrafiltration (UF) membranes. This sol was prepared based on water (>95 wt%), for which the hydrodynamic size of 8 nm could be obtained by tuning the electrostatic and steric repulsive forces, breaking the limit of the polymeric sol–gel method to prepare tight UF membranes. For the preparation of the sol, high water content can significantly reduce the use of organic solvents and is more environment-benign. Moreover, Ag doping can considerably improve the toughness of the supported membranes to efficiently prevent the TiO2/Ti composite membranes from cracking and overcome the thermal expansion mismatch of ceramic membranes and their metallic supports. The prepared Ag-doped TiO2/Ti composite membranes presented a molecular weight cut-off of 3 kDa with a pure water flux of 24 L m−2 h−1 bar−1 and exhibited good dye removal capabilities. The proposed Ag doping method has considerable potential for the fabrication of integrated hybrid ceramic–metallic composite membranes.

Chitosan encapsulation modulates the effect of capsaicin on the tight junctions of MDCK cells.

Capsaicin has known pharmacological effects including the ability to reversibly open cellular tight junctions, among others. The aim of this study was to develop a strategy to enhance the paracellular transport of a substance with low permeability (FITC-dextran) across an epithelial cell monolayer via reversible opening of cellular tight junctions using a nanosystem comprised by capsaicin and of chitosan. We compared the biophysical properties of free capsaicin and capsaicin-loaded chitosan nanocapsules, including their cytotoxicity towards epithelial MDCK-C7 cells and their effect on the integrity of tight junctions, membrane permeability and cellular uptake. The cytotoxic response of MDCK-C7 cells to capsaicin at a concentration of 500 μM, which was evident for the free compound, is not observable following its encapsulation. The interaction between nanocapsules and the tight junctions of MDCK-C7 cells was investigated by impedance spectroscopy, digital holographic microscopy and structured illumination fluorescence microscopy. The nanocapsules modulated the interaction between capsaicin and tight junctions as shown by the different time profile of trans-epithelial electrical resistance and the enhanced permeability of monolayers incubated with FITC-dextran. Structured illumination fluorescence microscopy showed that the nanocapsules were internalized by MDCK-C7 cells. The capsaicin-loaded nanocapsules could be further developed as drug nanocarriers with enhanced epithelial permeability.

Feasibility and safety of porcine Descemet's membrane as a carrier for generating tissue-engineered corneal endothelium.

The aim of this study was to evaluate the feasibility and safety of porcine Descemet's membrane (DM) as a carrier for the generation of tissue-engineered corneal endothelium by analyzing porcine endogenous retroviruses (PERVs) and the α-gal epitope. The morphology of porcine and human DM was observed by hematoxylin and eosin staining and scanning electron microscopy. Immunohistochemical staining was used to investigate the location of α-gal epitopes on porcine DM used for xenotransplantation. The porcine DM was treated with ethylene glycol diglycidyl ether (EDGE) for 2 weeks, and then the PERV gene sequences in porcine DM and DM-EDGE were detected by polymerase chain reaction (PCR) and real-time PCR, respectively. The porcine DM had tight basement membrane morphology, which was similar to human DM in terms of thickness. No positive immunohistochemical staining of the α-gal epitope was detected in porcine DM. PERV expression of pol, gag, env-A and env-B was noted in porcine DM, but in DM-EDGE it was completely degraded. Based on structural, immunological and etiological studies, porcine DM may be an ideal and viable carrier for the generation of tissue-engineered corneal endothelium.

Direct water reclamation from sewage using ceramic tight ultra- and nanofiltration

Sewage is a nutrient rich reliable water source that is rather consistent in quality, volume and temperature, and is available in large amounts in urban areas. Decentralised reclamation of water including its constituents from municipal sewage, further referred to as sewer mining, is a concept in which municipal sewage is considered a resource instead of a waste stream.In this research, water reclamation in the sewer mining concept was studied using ceramic tight ultra- (UF) and ceramic nanofiltration (NF). In our current approach, ceramic membrane filtration is proposed as pre-treatment for reverse osmosis (RO) to produce demineralised water for industries from municipal sewage. The objectives of this research are to study (i) the membrane performance, (ii) the organic matter and ion rejection, and (iii) the biofouling potential of RO using permeate water from the ceramic filtration.The application of ceramic tight UF and ceramic NF for direct treatment of domestic sewage has been demonstrated in this study. The cross flow ceramic tight UF and NF fed with filtered sewage, can be operated for 1–4days without any cleaning required. The membrane performance remained high with chemical cleaning with NaClO (0.1%) and HCl (0.1molL−1) solutions. On average about 81% of organic matter was rejected by both ceramic tight UF and NF membranes. Finally, the pressure drop increase in the MFS fed with ceramic NF permeate was low during an operation of 14days. These results were comparable with the increase in pressure drop of an MFS fed with Dutch drinking water.

Deficiency of angulin-2/ILDR1, a tricellular tight junction-associated membrane protein, causes deafness with cochlear hair cell degeneration in mice.

Tricellular tight junctions seal the extracellular spaces of tricellular contacts, where the vertices of three epithelial cells meet, and are required for the establishment of a strong barrier function of the epithelial cellular sheet. Angulins and tricellulin are known as specific protein components of tricellular tight junctions, where angulins recruit tricellulin. Mutations in the genes encoding angulin-2/ILDR1 and tricellulin have been reported to cause human hereditary deafness DFNB42 and DFNB49, respectively. To investigate the pathogenesis of DFNB42, we analyzed mice with a targeted disruption of Ildr1, which encodes angulin-2/ILDR1. Ildr1 null mice exhibited profound deafness. Hair cells in the cochlea of Ildr1 null mice develop normally, but begin to degenerate by two weeks after birth. Tricellulin localization at tricellular contacts of the organ of Corti in the cochlea was retained in Ildr1 null mice, but its distribution along the depth of tricellular contacts was affected. Interestingly, compensatory tricellular contact localization of angulin-1/LSR was observed in the organ of Corti in Ildr1 null mice although it was hardly detected in the organ of Corti in wild-type mice. The onset of hair cell degeneration in Ildr1 null mice was earlier than that in the reported Tric mutant mice, which mimic one of the tricellulin mutations in DFNB49 deafness. These results indicate that the angulin-2/ILDR1 deficiency causes the postnatal degenerative loss of hair cells in the cochlea, leading to human deafness DFNB42. Our data also suggest that angulin family proteins have distinct functions in addition to their common roles of tricellulin recruitment and that the function of angulin-2/ILDR1 for hearing cannot be substituted by angulin-1/LSR.

Pilot study for the treatment of sodium and fluoride-contaminated groundwater by using high-pressure membrane systems

High-pressure membrane process is one of the cost-effective technologies for the treatment of groundwater containing excessive dissolved solids. This paper reports a pilot study in treating a typical groundwater in Huaibei Plain containing excessive sodium, sulfate and fluoride ions. Three membrane systems were set up and two brands of reverse osmosis (RO), four low-pressure RO (LPRO) and one tight nanofiltration (NF) membranes were tested under this pilot study. An apparent recovery rate at about 75% was adopted. Cartridge filtration, in combination with dosing antiscalent, was not sufficient to reduce the fouling potential of the raw water. All RO and LPRO systems (except for the two severely affected by membrane fouling) demonstrated similar rejection ratios of the conductivity (∼98.5%), sodium (∼98.5%) and fluoride (∼99%). Membrane fouling substantially reduced the rejection performance of the fouled membranes. The tight NF membrane also had a good rejection on conductivity (95%), sodium (94%) and fluoride (95%). All membranes rejected sulfate ion almost completely (more than 99%). The electricity consumptions for the RO, LPRO and NF systems were 1.74, 1.10 and 0.72 kWh·m−3 treated water, respectively. The estimated treatment costs by using typical RO, LPRO and tight NF membrane systems were 1.21, 0.98 and 0.96 CNY·m−3 finished water, respectively. A treatment process consisting of either LPRO or tight NF facilities following multi-media filtration was suggested.

Polaprezinc attenuates cyclophosphamide-induced cystitis and related bladder pain in mice

Cav3.2 T-type Ca2+ channels targeted by H2S, a gasotransmitter, participate in cyclophosphamide-induced cystitis and bladder pain. Given that zinc selectively inhibits Cav3.2 among T-channel isoforms and also exhibits antioxidant activity, we examined whether polaprezinc (zinc-l-carnosine), a medicine for peptic ulcer treatment and zinc supplementation, reveals preventive or therapeutic effects on bladder inflammation and/or pain in the mouse with cyclophosphamide-induced cystitis, a model for interstitial cystitis. Systemic administration of cyclophosphamide caused cystitis-related symptoms including increased bladder weight and vascular permeability, and histological signs of bladder edema, accompanied by bladder pain-like nociceptive behavior/referred hyperalgesia. All these symptoms were significantly attenuated by oral preadministration of polaprezinc at 400 mg/kg. The same dose of polaprezinc also prevented the increased malondialdehyde level, an indicator of lipid peroxidation, and protein upregulation of cystathionine-γ-lyase, an H2S-generating enzyme, but not occludin, a tight junction-related membrane protein, in the bladder tissue of cyclophosphamide-treated mice. Oral posttreatment with polaprezinc at 30–100 mg/kg reversed the nociceptive behavior/referred hyperalgesia in a dose-dependent manner without affecting the increased bladder weight. Together, our data show that zinc supplementation with polaprezinc prevents the cyclophosphamide-induced cystitis probably through the antioxidant activity, and, like T-channel blockers, reverses the established cystitis-related bladder pain in mice, suggesting novel therapeutic usefulness of polaprezinc.

Physical Properties and Membrane Packing in Hybrid Archaeosomes

In this study, we have characterized the physical properties of liposomes made of archaeal bipolar tetraether lipids (BTL) and “conventional” monopolar diester lipids (termed as hybrid archaeosomes). We used the polar lipid fraction E (PLFE) isolated from the thermoacidophilic archaeon Sulfolobus acidocaldarius as the BTL component of the hybrid archaeosomes. Hybrid archaeosomes were made by extrusion with the particle size ranging from 100-300 nm. Dynamic light scattering and zeta potential measurements showed that the presence of PLFE greatly stabilizes liposomes. The steady-state polarization of DPH fluorescence in PLFE/PC mixtures decreases with increasing temperature (18-56oC) in a molar ratio dependent manner. At low temperatures, hybrid archaeosomes have membrane packing, as inferred from DPH polarization, similar to that in gel state of disaturated PC bilayers. At the high temperature end, membrane packing of the hybrid archaeosomes is significantly tighter than that of PC fluid state. A similar conclusion can be drawn from the studies using Laurdan's generalized polarization. Additionally, due to tight membrane packing, drug release from hybrid archaeosome is much slower than from liposomes composed of only diester lipids. Confocal fluorescence microscopy showed that these hybrid archaeosomes can be taken up by live cells (e.g., MCF-7 breast cancer cells) and deliver entrapped drug molecules to the cell's nucleus, but with a rate significantly lower than that obtained from conventional diester liposomes.

Nanofiltration of oil sands boiler feed water: Effect of pH on water flux and organic and dissolved solid rejection

Nanofiltration (NF) is a promising advanced treatment technique for oilfield wastewaters. In this study, we performed a crossflow NF on model boiler feed water (BFW) obtained from a thermal in-situ bitumen recovery process called steam assisted gravity drainage (SAGD) with the intent to remove dissolved organic matter and silica. Nanofiltration with a tight NF membrane was selected as the treatment technique since it provided reasonable product quality in a single-stage process and was found to be more energy efficient than reverse osmosis (RO). Two different feed pH values, 8.5 and 10.5, were investigated. Total organic carbon (TOC) and Si rejection of approximately 98% and divalent cation rejection greater than 99% was achieved at both pH values. Higher total dissolved solids (TDS) rejection, but lower flux rates were seen at pH 8.5 compared to pH 10.5. Surface characterization of the fouled membranes indicated the presence of organics (primarily carbon and oxygen) and inorganics (mainly silicon and iron) in the fouling deposits. Larger amounts of deposit were seen at pH 8.5 compared to pH 10.5. Increasing feed pH from 8.5 to 10.5 recovered the water flux more than 20% which demonstrated the critical role of pH as a pulsation technique to reduce membrane fouling. Fluorescence excitation emission matrix spectroscopy (FEEMs) on the feed and permeate showed that the organic matter that passed through the membrane was mainly hydrophilic compounds. Overall, this research indicated that NF is a viable treatment process for silica and TOC removal for SAGD BFW.

Cellulose nanopapers as tight aqueous ultra-filtration membranes

Recently, we have demonstrated the use of wood-derived nanocellulose papers, herein termed nanopapers, for organic solvent nanofiltration applications. In this study, we extend the use of these nanopapers to tight ultrafiltration (UF) membranes. The feasibility of such nanopaper-based UF membranes intended for use in water purification is shown. Four types of nanocelluloses, namely bacterial cellulose, wood-derived nanocellulose, TEMPO-oxidized cellulose nanofibrils and cellulose nanocrystals, were used as raw materials for the production of these nanopaper-based membranes. The resulting nanopapers exhibit a transmembrane permeance in the range of commercially available tight UF membranes with molecular weight cut-offs ranging from 6 to 25kDa, which depends on the type of nanocellulose used. These molecular weight cut-offs correspond to average pore sizes of a few nanometres. The rejection performance of the nanopapers is on the border of nanofiltration and UF. We demonstrate that the pore size of the nanopapers can be controlled by using different types of nanocellulose fibrils.

Recovery of caustic from mercerizing wastewaters of a denim textile mill

The objective of this study was to evaluate caustic recovery from mercerizing wastewater originating from a denim textile producing plant using membrane technology. For this purpose, ultrafiltration (UF) and nanofiltration (NF) processes were considered. In the first stage, in an attempt to control the possible membrane fouling, pretreatment alternatives of flocculation, centrifugation, and microfiltration were evaluated. These pretreatment application alternatives were unsuccessful as they did not provide considerable color and solids removal. In the second stage, UF and NF processes were tested using a tight UF membrane (GR95PP, Alfalaval) and three NF membranes (NP010 and NP030, Microdyn Nadir, and MPF34, Koch Membranes) to accomplish the caustic recovery without applying any pretreatment. The best performance was obtained with NP010 NF in terms of permeate flux along with color and COD rejections. Then, for this membrane the effects of transmembrane pressure (4.03 and 6.23 bar), cross-flow velocity (from 0.40 to 1.40 m/s), and feed temperature (20 and 40°C) were investigated. Temperature positively affected the permeate flux without significant loss in recovery and rejections. Caustic stream produced had about 98–100% of NaOH in the feed at a concentration of 30–40 g/L and therefore was recyclable after a concentration process.

Membrane treatment of the bleaching plant (EPO) filtrate of a kraft pulp mill

The objective of this study was to evaluate the use of membrane technology to treat oxygen and peroxide-reinforced extraction stage (EPO) filtrate from a kraft pulp mill bleach plant. Three different types of tubular membranes were tested in a pilot plant: (i) tight ultrafiltration (UF); (ii) open UF followed by nanofiltration (UF+NF); and (iii) nanofiltration (NF). According to the separation performance, considering the chemical oxygen demand (COD) and colour removal, permeate flux, operational simplicity and cost, the results indicated that the best option for treatment of (EPO) filtrates was the tight UF membrane. This membrane obtained a COD removal of 79% with a colour reduction of 86%. The effect of (EPO) filtrate UF treatment on the mill effluent treatment plant was evaluated. Compared with the actual mill effluent, the results indicated that if the UF permeate was recycled in the bleaching area, the COD reduction efficiency increased by 7%, the final effluent colour decreased by 8%, the biological sludge production decreased by 18%, and the energy consumption decreased by 40%. In the tertiary treatment plant, the coagulant dosage decreased by 40%, and the tertiary sludge production decreased by 46%.

The impact of EfOM, NOM and cations on phosphate rejection by tight ceramic ultrafiltration

Reverse osmosis (RO) systems for secondary effluent water reuse frequently encounter severe biofouling due to the high nutrient concentration in the RO feed water. Deployment of negatively charged tight ceramic ultrafiltration (UF) may restrict biofouling in RO by phosphate limitation, since the tight ceramic UF can reject dissolved phosphate by electrostatic interactions. However, the organic matter and cations can potentially impact phosphate rejection by tight ceramic UF. In this study, the effects of organic matter and Ca2+ on phosphate rejection by the 3kDa tight ceramic UF membrane were investigated, using synthetic water containing natural organic matter (NOM) and effluent organic matter (EfOM), as well as secondary effluent water. Phosphate rejection was found to be linearly correlated to the zeta potential of the organics in the membrane feed water when the membrane was fouled by NOM. Furthermore, the EfOM-fouled membrane yielded higher phosphate rejection than the membrane fouled by the NOM due to additional adsorption of phosphate by the biopolymers. A preferential phosphate rejection was observed during effluent water filtration by the 3kDa tight ceramic UF membrane.

Cargo binding to Atg19 unmasks additional Atg8 binding sites to mediate membrane–cargo apposition during selective autophagy

Autophagy protects cells from harmful substances such as protein aggregates, damaged mitochondria and intracellular pathogens and has been implicated in a variety of diseases. Selectivity of autophagic processes is mediated by cargo receptors that link cargo to Atg8 family proteins on the developing autophagosomal membrane. To avoid collateral degradation during constitutive autophagic pathways the autophagic machinery must not only select cargo but also exclude non-cargo material. Here we show that cargo directly activates the cargo receptor Atg19 by exposing multiple Atg8 binding sites. Furthermore, Atg19 mediates tight apposition of the cargo and Atg8-coated membranes in a fully reconstituted system. These properties are essential for the function of Atg19 during selective autophagy in vivo. Our results suggest that cargo receptors contribute to tight membrane bending of the isolation membrane around the cargo.