Membrane Phosphate Research Articles

Nickel-cobalt hydrogen phosphate membrane with outstanding anti-crude oil-fouling capability and its microscopic anti-fouling mechanism

Oil/water separation membranes with superior anti-fouling properties against highly viscous oils are crucial for the efficient treatment of oily wastewater. Herein, the effects of functional groups in an inorganic superhydrophilic membrane on the anti-fouling properties of the membrane are investigated. Using a facile one-step electrochemical deposition method, Ni1-xCoxHPO4·3H2O membranes were formed on a Cu(OH)2 microneedle-coated copper mesh (CCNC–P) with superhydrophilic and underwater superoleophobic properties. All CCNC–P membranes with different Co2+ contents showed outstanding anti-fouling capability for oily wastewater such as those containing crude oil. The CCNC–P(x = 0.5) membrane exhibited high separation efficiency reaching 99.7 % across five oil–water mixtures and oil-in-water emulsions, concurrently presenting an ultrahigh flux of 61695 L m−2 h−1 for crude oil–water mixture. Moreover, the membrane consistently maintained its separation performance during the long-term crude oil–water separation process. The flux decline ratio was below 1 %, and the flux recovery ratio approached 99.4 %. The CCNC–P membranes possessed superior chemical, thermal, and mechanical stability, suggesting significant potential for the industrial treatment of oily wastewater. Density functional theory calculation revealed that the HPO42− group in CCNC–P can strongly adsorb water molecules. The resultant stabilized hydration layer impeded the contact between the membrane surface and oil droplets, while the metal ions scarcely influenced the adsorption of water molecules on CCNC–P. These findings provide new insights into the development of novel oil–water separation membranes with higher anti-fouling capabilities against high-viscosity oils.

A novel chitosan-alginate-dicalcium phosphate membrane coated on poly(lactic acid) to control biological condition, swelling and cell growth

A novel chitosan-alginate-dicalcium phosphate membrane coated on poly(lactic acid) to control biological condition, swelling and cell growth

A reverse-selective ion exchange membrane for the selective transport of phosphates via an outer-sphere complexation-diffusion pathway.

Specific-ion selectivity is a highly desirable feature for the next generation of membranes. However, existing membranes rely on differences in charge, size and hydration energy, which limits their ability to target individual ion species. Here we demonstrate a nanocomposite ion-exchange membrane material that enables a reverse-selective transport mechanism that can selectively pass a single ion species. We demonstrate this transport mechanism with phosphate ions selectively transporting across negatively charged cation exchange membranes. Selective transport is enabled by the in situ growth of hydrous manganese oxide nanoparticles throughout a cation exchange membrane that provide a diffusion pathway via phosphate-specific, reversible outer-sphere interactions. On incorporating the hydrous manganese oxide nanoparticles, the membrane's phosphate flux increased by a factor of 27 over an unmodified cation exchange membrane, and the selectivity of phosphorous over sulfate, nitrate and chloride reaches 47, 100 and 20, respectively. By pairing ion-specific outer-sphere interactions between the target ions and appropriate nanoparticles, these nanocomposite ion-exchange materials can, in principle, achieve selective transport for a range of ions.

In Vitro Biocompatibility of a Novel Semi-Rigid Shell Barrier System: As a New Application for Guided Bone Regeneration.

This study evaluated the in vitro biocompatibility of a novel, semi-rigid shell barrier system for guided bone regeneration (GBR) based on polycaprolactone and biphasic calcium phosphate membranes and consisting of a semi-rigid shell (SR) and two semi-resorbable barrier membranes, i.e., a buffered (BF) and an airdried (AD) membrane. In vitro biocompatibility, cell cytotoxicity, cell proliferation and differentiation were evaluated with osteoblast (MC3T3-E1) and fibroblast (L929) cells compared to the d-PTFE membrane (Cytoplast®, CP). The osteoblasts and fibroblasts were well attached and proliferated on all materials from days 1, 3, and 7 without cell cytotoxicity. All groups showed that osteoblast and fibroblast cell proliferation increased from day 1 to day 14–17 and decreased on day 21. On day 21, the CP membrane presented significantly higher osteoblast cell numbers than the BF membrane and the SR shell (p = 0.000). The CP membrane presented a significantly higher amount of fibroblast cells than the other groups (p = 0.000). The SR shell and the BF membrane demonstrated higher osteoblast cell differentiation markers including ALP activity, osteocalcin, and mineral secretion than the CP and the AD membrane. The semi-rigid shell barrier system demonstrated good in vitro biocompatibility and supported osteogenic cell proliferation and differentiation better than the d-PTFE membrane.

A Novel Immunoregulatory PEGylated Poly(glycerol sebacate)/β‐TCP Membrane for Application in Guided Bone Regeneration

AbstractThe recently developed poly(ethylene glycol)ylated poly(glycerol sebacate)/β‐tricalcium phosphate (PEGS/β‐TCP) membrane possesses favorable mechanical properties and excellent osteogenic activity. This study is designed to evaluate the feasibility of applying PEGS/β‐TCP membrane in guided bone regeneration (GBR) through investigating the in vitro and in vivo activities of macrophages promoted by PEGS/β‐TCP membranes during osteogenesis. The behavior of macrophages seeded on PEGS/β‐TCP and PEGS membranes is assessed in terms of cell viability, polarization pattern, and release of inflammatory and osteogenic cytokines. The in vitro osteogenic effect of PEGS/β‐TCP membrane‐associated macrophage polarization is evaluated by incubating mesenchymal stem cells (MSCs) with conditioned medium derived from macrophages stimulated with PEGS/β‐TCP or PEGS membranes. The in vivo correlation between macrophage polarization and PEGS/β‐TCP membrane‐driven osteogenesis is investigated using a rat calvarial defect model. The results show that PEGS/β‐TCP and PEGS membranes are capable of downregulating M1 polarization and upregulating M2 polarization. Compared to the PEGS membrane, the PEGS/β‐TCP membrane can further alleviate local inflammatory response and significantly promote the in vitro osteogenic differentiation of MSCs and in vivo restoration of bone defects. In conclusion, the novel PEGS/β‐TCP membrane can promote the osteogenic commitment of MSCs and restore calvarial bone defects by improving the macrophage polarization pattern.

Low-cost ceramic microfiltration membrane made from natural phosphate for pretreatment of raw seawater for desalination

A novel ceramic microfiltration (MF) membrane was prepared from natural phosphate and its properties were thoroughly characterized. An investigation of the effect of sintering temperature on the features of phosphate membrane was carried out in the range from 900 to 1100 °C. The optimized membrane sintered at 1000 °C exhibits 697 L h−1 m-2 bar−1 of permeability, 25.6 % of porosity, 0.26 μm of average pore size and 19.7 MPa of flexural strength. When evaluated for filtration of raw seawater as a potential pretreatment for reverse osmosis desalination, the prepared membrane reduced total organic carbon (TOC) and turbidity by 73 and 98 %, respectively, as well as reducing silt density index (SDI) from 5.41 to 3.25. Furthermore, the fouling mechanism and the flux recovery were also studied. Finally, simple cleaning of the prepared membrane performed after the MF experiment led to recover 74 % of its original water flux.

Optical and gas-sensing property enhancement of membranes based on lithium iron phosphate particles with different dispersants

Lithium iron phosphate (LiFePO4) membranes were fabricated by coating LiFePO4 particles dispersed in various dispersants on tin-diffused glass slides and alumina ceramic tubes for xylene gas detection. The influences of dispersants, including polyvinyl alcohol (PVA), sodium dodecylbenzene sulfonate (SDBS), and methyl methacrylate (MMA), on the optical properties and opto-electrical gas-sensing performance of the LiFePO4 particle-based membranes were investigated. The LiFePO4 particle-based membrane, prepared using PVA, exhibited less agglomeration, better transparency, optimum refractive index, and a higher response toward xylene gas at concentrations of 10 ppb to 1000 ppm in a planar optical waveguide sensor. However, in a resistance-type electrochemical sensing system at room temperature, the LiFePO4-PVA membrane exhibited low response even at high xylene concentrations. The membranes sensitivities increased in the order MMA < SDBS < PVA. After dispersing in PVA, the membrane sensitivity toward xylene was increased ~ 100 times, proving the positive effects of PVA on the optical properties and gas-sensing performance of LiFePO4 particles.

Transcriptional Patterns of Biogeochemically Relevant Marker Genes by Temperate Marine Bacteria.

Environmental microbial gene expression patterns remain largely unexplored, particularly at interannual time scales. We analyzed the variability in the expression of marker genes involved in ecologically relevant biogeochemical processes at a temperate Atlantic site over two consecutive years. Most of nifH transcripts, involved in nitrogen (N) fixation, were affiliated with the symbiotic cyanobacterium Candidatus Atelocyanobacterium thalassa, suggesting a key role as N providers in this system. The expression of nifH and amoA (i.e., marker for ammonia oxidation) showed consistent maxima in summer and autumn, respectively, suggesting a temporal succession of these important N cycling processes. The patterns of expression of genes related to the oxidation of carbon monoxide (coxL) and reduced sulfur (soxB) were different from that of amoA, indicating alternate timings for these energy conservation strategies. We detected expression of alkaline phosphatases, induced under phosphorus limitation, in agreement with the reported co-limitation by this nutrient at the study site. In contrast, low-affinity phosphate membrane transporters (pit) typically expressed under phosphorus luxury conditions, were mainly detected in post-bloom conditions. Rhodobacteraceae dominated the expression of soxB, coxL and ureases, while Pelagibacteraceae dominated the expression of proteorhodopsins. Bacteroidetes and Gammaproteobacteria were major contributors to the uptake of inorganic nutrients (pit and amt transporters). Yet, in autumn, Thauma- and Euryarchaeota unexpectedly contributed importantly to the uptake of ammonia and phosphate, respectively. We provide new hints on the active players and potential dynamics of ecologically relevant functions in situ, highlighting the potential of metatranscriptomics to provide significant input to future omics-driven marine ecosystem assessment.

Study of coupling photocatalysis and membrane separation using tubular ceramic membrane made from natural Moroccan clay and phosphate

This paper is devoted to study the feasibility of combining photocatalytic degradation with membrane filtration for the removal of organic pollutants. As a result, we have successfully prepared low-cost microfiltration membranes based on clay and phosphate. It is expected that the phosphate and clay composite membrane can have multifunctional separation and photocatalysis simultaneously and this type of composite membrane can play an important role in the photocatalytic reaction in presence of TiO2 and the separation process. We then tested the efficiency of the direct coupling of photodegradation and filtration to determine the rate of release of TiO2 particles through the microfiltration membrane. However, we have seen that the recovery of TiO2 exceeds a 96%, as well as the removal of products from the photodecomposition of the reaction mixture in the membrane photocatalytic reactor. In our case the methylene blue elimination rate exceeds 75%.

Effect of Late Endosomal Dobmp Lipid and Traditional Model Lipids of Electrophysiology on the Anthrax Toxin Channel Activity

Abstract Anthrax toxin action requires triggering of natural endocytic transport mechanisms whereby the binding component of the toxin forms channels (PA63) within endosomal limiting and intraluminal vesicle membranes to deliver the toxin's enzymatic components into the cytosol. Membrane lipid composition varies at different stages of anthrax toxin internalization, with intraluminal vesicle membranes containing ~70% of anionic bis(monoacylglycero)phosphate lipid. Using model bilayer measurements, we show that membrane lipids can have a strong effect on the anthrax toxin channel properties, including the channel-forming activity, voltage-gating, conductance, selectivity, and enzymatic factor binding. Interestingly, the highest PA63 insertion rate was observed in bis(monoacylglycero)phosphate membranes. The molecular dynamics simulation data show that the conformational properties of the channel are different in bis(monoacylglycero)phosphate compared to PC, PE, and PS lipids. The anthrax toxin protein/lipid bilayer system can be advanced as a novel robust model to directly investigate lipid influence on membrane protein properties and protein/protein interactions.

Molecular interactions and physico-chemical characterization of quercetin-loaded magnetoliposomes.

The bioflavonoid quercetin may prevent magnetoliposomes oxidation, preserving their stability. In this work, the interaction between quercetin and asolectin-based magnetoliposomes was investigated by monitoring the hydration degree, vibrational, rotational and translational mobility parameters of the system as well as its thermodynamic properties. The efficiency of the encapsulation of maghemite magnetic nanoparticles was detected by high resolution-continuum source flame atomic absorption spectrometry (HR-CS FAAS). The magnetic behavior of the system was studied by vibrating sample magnetometry (VSM) technique. The size and surface charge of magnetoliposomes were detected by dynamic light scattering (DLS) and zeta potential (ζ-potential) measurements. The influence of quercetin on the physico-chemical parameters of the magnetoliposomes was evaluated by Fourier transform infrared spectroscopy (FTIR), 31P and 1H nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC) techniques. In vitro antioxidant and antitumoral assays were also performed for the magnetoliposomes. An insertion of quercetin into magnetoliposomes reduced the efficiency of the encapsulation of maghemite nanoparticles by 11%, suggesting a significant interaction between flavonoid and nanoparticles in a specific region of the system. Quercetin discreetly decreased the saturation magnetization of magnetoliposomes, but did not affect the superparamagnetic behavior of the system. 31P and 1H NMR results showed that quercetin did not alter the inverted hexagonal system phase state but decreased lipid polar head mobility. The flavonoid also seems to reorient the choline group above the bilayer phosphate membrane plane, as indicated by ζ-potential system values. FTIR, NMR and DSC responses showed that quercetin disordered the carbonyl and the methylene regions of the magnetoliposomes. Quercetin, as the nanoparticles, seems to be located in the polar head regions of magnetoliposomes, ordering it and diminishing the lipid intermolecular communication in the membrane carbonyl and non-polar regions. The lipid peroxidation of the magnetoliposomes was prevented 8-fold by the presence of quercetin in the system. Also, the flavonoid was responsible for a 45% reduction in the viability of glioma cells. Location and interactions between quercetin and magnetoliposomes components were discussed in order to be correlated with the results of biological activity, contributing to the design of more stable and efficient magnetoliposomes to be applied as contrast and antitumoral agents.

Transport properties of blended sulfonated poly(styrene‐isobutylene‐styrene) and isopropyl phosphate membranes

AbstractThis work discusses the effect of isopropyl phosphate (IP) on the transport properties of sulfonated poly(styrene‐isobutylene‐styrene) (SO3H SIBS) as membranes for direct methanol fuel cell (DMFC) and chemical and biological protective clothing (CBPC) applications. The properties were determined as a function of SIBS sulfonation level (i.e., 24, 34, 49, and 84 mol %) and IP loading (i.e., 1, 3, 5, 11, and 15 wt %). A comprehensive material characterization study (e.g., FTIR, TGA, AFM, and SAXS) was performed to confirm the presence of the phosphate groups in the polymer matrix, assess the thermal stability of the proton‐exchange membranes (PEMs), and understand how the unique interactions between the phosphate and sulfonic groups influenced the nanostructure of SO3H SIBS. The transport properties, water absorption capabilities (i.e., swelling ratio, water uptake, etc.), oxidative stability, and ion‐exchange capacity (IEC) were performed to evaluate the impact of IP on the properties of the resulting solvent‐casted membranes. Results suggest that the morphology, thermal stability, and vapor permeability are governed by the sulfonation level, whereas the IEC, oxidative stability, water absorption capabilities, and the rest of the transport properties are dominated by the ionic content (i.e., sulfonic and phosphate groups) and their synergistic effects. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47009.

Effect of late endosomal DOBMP lipid and traditional model lipids of electrophysiology on the anthrax toxin channel activity

Anthrax toxin action requires triggering of natural endocytic transport mechanisms whereby the binding component of the toxin forms channels (PA63) within endosomal limiting and intraluminal vesicle membranes to deliver the toxin's enzymatic components into the cytosol. Membrane lipid composition varies at different stages of anthrax toxin internalization, with intraluminal vesicle membranes containing ~70% of anionic bis(monoacylglycero)phosphate lipid. Using model bilayer measurements, we show that membrane lipids can have a strong effect on the anthrax toxin channel properties, including the channel-forming activity, voltage-gating, conductance, selectivity, and enzymatic factor binding. Interestingly, the highest PA63 insertion rate was observed in bis(monoacylglycero)phosphate membranes. The molecular dynamics simulation data show that the conformational properties of the channel are different in bis(monoacylglycero)phosphate compared to PC, PE, and PS lipids. The anthrax toxin protein/lipid bilayer system can be advanced as a novel robust model to directly investigate lipid influence on membrane protein properties and protein/protein interactions.

Optimisation of Proton‐Conducting sPEEK Membranes through a Thermal Treatment Method Monitored by Dielectric Spectroscopy

AbstractThe Sulfonated Poly (Ether Ether Ketone) (sPEEK) is used in many of the developments of polymer electrolyte membranes for fuel cells. In this publication, it is proven that the water in the sPEEK membrane creates channels in the sulfonated clusters by interacting with the sulfonic groups, and changing the glass transition temperature (Tg) of the material. It is shown that, for conductivity, apart from water in the membrane, order is needed in the water channels because it has an impact on how fast the protons pass through the membrane. This research focuses on how various thermal treatment, performed under a pre‐stated conditioning; allow the free alignment of the inner phases, influencing their order. It is demonstrated how is possible to use of differential calorimetry, dielectric measurements and X‐ray to follow these changes, and how to used Broadband Dielectric Spectroscopy to forecast the most optimal and stable thermal treatment for the highest proton conduction in sPEEK. The methodology is also test successfully on a hybrid sPEEK/Boron Phosphate membrane.

A pilot study: Clinical efficacy of novel polycaprolactone-tricalcium phosphate membrane for guided bone regeneration in rabbit calvarial defect model

In this pilot study, we aim to investigate the clinical efficacy of a novel polycaprolactone-tricalcium phosphate (PCL-TCP) membrane for guided bone regeneration (GBR) in an in vivo model. Eight rabbits, each with two surgically created calvarial defects were reconstructed using a bovine particulate bone substitute, then covered with a mechanical barrier using a PCL-TCP or collagen membrane, or left uncovered without any membrane. The rabbits were sacrificed at 1 and 2 months and the reconstructed defects were harvested for histology and histomorphometry evaluations. Results showed no statistical significance in percentage bone area fraction (BAF%) between the PCL-TCP and collagen membranes at 1 and 2 months. The BAF% of the PCL-TCP membrane group was statistically higher at 2 months compared to 1 month (p<.05); the BAF% in the collagen membrane group did not increase significantly from the first to second months (p>.05). We postulate that this is attributed to the greater stiffness and slower degradation of PCL-TCP. We conclude that the novel PCL-TCP membrane is as effective as the commercially available collagen membrane as a mechanical barrier for GBR, with good handling characteristics. Future work should explore variations in PCL-TCP composition to further improve its usability and rate of desired degradation.

Determining the effects of PEI adsorption on the permeability of 1,2-dipalmitoylphosphatidylcholine/bis(monoacylglycero)phosphate membranes under osmotic stress.

In recent decades, researchers have investigated polyamine-based gene delivery systems as useful alternatives to viral gene carriers. One step that is crucial to the performance of polyamine gene carriers such as polyethylenemine (PEI) is escape from late endosomal vesicles during intracellular delivery. However, the ability of polyamine/DNA polyplexes to effectively escape from endosomes is a little-understood part of the gene therapy techniques that use these polyplexes. Here, we performed investigations using monolayers and vesicles derived from a mixture of neutral and negative lipids (1,2-dipalmitoylphosphatidylcholine (DPPC) and bis(monoacylglycero)phosphate (BMP), respectively) as model systems for late endosomes in order to examine the interactions of PEI with the DPPC/BMP membranes and study the subsequent effects on the stability and permeability of these membranes.

Fabrication and optimization of Cu(II) ion selective membrane electrode

In this study, the fabrication, performance characteristics and application of a Cu(II) ion selective pyridine based thorium(IV) phosphate membrane electrode are studied. The membrane electrode exhibited a fast response time of 10 s, the wide linear response in the concentration of 1 × 10–1 to 1 × 10–7 M of Cu (II) ions with a slope of 27.60 mV/decade change in concentration and a lifetime of 4 months. The potentiometric response revealed that the potentials are independent of pH in the wide range of 3.0–6.5. It was also used as an indicator electrode in the potentiometric titration of Cu(II) ions using ethylenediamine tetraacetic acid, disodium salt.

Effects of 3D-Printed Polycaprolactone/β-Tricalcium Phosphate Membranes on Guided Bone Regeneration.

This study was conducted to compare 3D-printed polycaprolactone (PCL) and polycaprolactone/β-tricalcium phosphate (PCL/β-TCP) membranes with a conventional commercial collagen membrane in terms of their abilities to facilitate guided bone regeneration (GBR). Fabricated membranes were tested for dry and wet mechanical properties. Fibroblasts and preosteoblasts were seeded into the membranes and rates and patterns of proliferation were analyzed using a kit-8 assay and by scanning electron microscopy. Osteogenic differentiation was verified by alizarin red S and alkaline phosphatase (ALP) staining. An in vivo experiment was performed using an alveolar bone defect beagle model, in which defects in three dogs were covered with different membranes. CT and histological analyses at eight weeks after surgery revealed that 3D-printed PCL/β-TCP membranes were more effective than 3D-printed PCL, and substantially better than conventional collagen membranes in terms of biocompatibility and bone regeneration and, thus, at facilitating GBR.

Evaluation of 3D printed PCL/PLGA/β-TCP versus collagen membranes for guided bone regeneration in a beagle implant model

Here, we compared 3D-printed polycaprolactone/poly(lactic-co-glycolic acid)/β-tricalcium phosphate (PCL/PLGA/β-TCP) membranes with the widely used collagen membranes for guided bone regeneration (GBR) in beagle implant models. For mechanical property comparison in dry and wet conditions and cytocompatibility determination, we analyzed the rate and pattern of cell proliferation of seeded fibroblasts and preosteoblasts using the cell counting kit-8 assay and scanning electron microscopy. Osteogenic differentiation was verified using alizarin red S staining. At 8 weeks following implantation in vivo using beagle dogs, computed tomography and histological analyses were performed after sacrifice. Cell proliferation rates in vitro indicated that early cell attachment was higher in collagen than in PCL/PLGA/β-TCP membranes; however, the difference subsided by day 7. Similar outcomes were found for osteogenic differentiation, with approximately 2.5 times greater staining in collagen than PCL/PLGA/β-TCP, but without significant difference by day 14. In vivo, bone regeneration in the defect area, represented by new bone formation and bone-to-implant contact, paralleled those associated with collagen membranes. However, tensile testing revealed that whereas the PCL/PLGA/β-TCP membrane mechanical properties were conserved in both wet and dry states, the tensile property of collagen was reduced by 99% under wet conditions. Our results demonstrate in vitro and in vivo that PCL/PLGA/β-TCP membranes have similar levels of biocompatibility and bone regeneration as collagen membranes. In particular, considering that GBR is always applied to a wet environment (e.g. blood, saliva), we demonstrated that PCL/PLGA/β-TCP membranes maintained their form more reliably than collagen membranes in a wet setting, confirming their appropriateness as a GBR membrane.

Comparative Efficacies of a 3D-Printed PCL/PLGA/β-TCP Membrane and a Titanium Membrane for Guided Bone Regeneration in Beagle Dogs

This study was conducted to evaluate the effects of a 3D-printed resorbable polycaprolactone/poly(lactic-co-glycolic acid)/β-tricalcium phosphate (PCL/PLGA/β-TCP) membrane on bone regeneration and osseointegration in areas surrounding implants and to compare results with those of a non-resorbable titanium mesh membrane. After preparation of PCL/PLGA/β-TCP membranes using extrusion-based 3D printing technology; mechanical tensile testing and in vitro cell proliferation testing were performed. Implant surgery and guided bone regeneration were performed randomly in three groups (a no membrane group, a titanium membrane group, and a PCL/PLGA/β-TCP membrane group (n = 8 per group)). Histological and histometric analyses were conducted to evaluate effects on bone regeneration and osseointegration. Using the results of mechanical testing; a PCL/PLGA/β-TCP ratio of 2:6:2 was selected. The new bone areas (%) in buccal defects around implants were highest in the PCL/PLGA/β-TCP group and significantly higher than in the control group (p &lt; 0.05). Bone-to-implant contact ratios (%) were also significantly higher in the PCL/PLGA/β-TCP and titanium groups than in the control group (p &lt; 0.05). When the guided bone regeneration procedure was performed using the PCL/PLGA/β-TCP membrane; new bone formation around the implant and osseointegration were not inferior to those of the non-resorbable pre-formed titanium mesh membrane.