Membrane Surface Research Articles

Thin Polyamide Layer Cross-Linked Graphene-Oxide based Ceramic Membranes for Efficient Separation of the Surfactant Stabilized Oil-In-Water Emulsions

Thin Polyamide Layer Cross-Linked Graphene-Oxide based Ceramic Membranes for Efficient Separation of the Surfactant Stabilized Oil-In-Water Emulsions

Impacts of ohmic-heating on the surface characteristics, membrane integrity, morphology, and chemical compounds of Bifidobacterium animalis paraprobiotic

The aim of this paper was to obtain paraprobiotic from Bifidobacterium animalis subsp. lactis Bb-12 (BB) with a promising ohmic-heating (OH) condition through response surface modeling, based on the flow cytometry and spectrophotometry analyses. Some properties of the obtained BB paraprobiotic (BBP) were studied, including the cell surface hydrophobicity (CSH), cell auto- and co-aggregation (CAA and CCA), and membrane integrity (MI). Among fitted models, the linear model was more accurate for co-aggregation (R2-pred 85.77%), and the quadratic model for CSH (R2-pred: 84.17%), auto-aggregation (R2-pred=87.25%), MI (R2-pred: 83.65%). The electric field (EF) had the most destructive effect on the MI of BBP. However, OH temperature had the most enhancing effect on the surface characteristics. The surface characteristics of BBP (CSH: 44.82, CAA: 38.05, and CCA: 40.79) obtained by the OH process at optimum condition was remarkably more than BB without OH treatment (CSH: 34.21, CAA: 27.18, and CCA: 28.5). The confirming analysis regarding the MI changes was performed successfully by scanning electron microscopy analysis. Lactic and acetic acids were the most amounts of characterized metabolites in BBP and BB. The OH condition, including EF of 8 V/cm, OH temperature of 88˚C, BB population of 8 (log CFU/mL), and OH time of 3 min, were considered optimum condition. At this optimum OH condition, the responses for CSH, CAA, CCA, and MI were observed 44.82, 38.05, 40.79, and 94.82 %, respectively.

Power feasibility of single-staged full-scale PRO systems with hypersaline draw solutions

Pressure retarded osmosis (PRO) is a process that allow to generate energy from osmotic gradient. This process uses selective membranes in order to produce electrical energy through a hydraulic turbine. PRO can be used as a renewable energy technology where water resources are inexhaustible. PRO has the advantage of knowing when and how much energy will be produced. Unfortunately at the moment there are certain limiting factors concerning membrane and module characteristics that have prevented PRO to be fully exploited at full-scale. This study aims to assess the impact of hypersaline draw solutions (60–180 g L−1), membrane characteristics such as structural parameter, module membrane surface and permeability coefficients on the net energy generated by single-staged full-scale PRO system with up to 8 spiral wound membrane modules (SWMMs) in series in a pressure vessel. To carry out this study, characteristics of existing PRO membranes at lab-scale were scaled up to 8 inches SWMM. The results showed the change in the optimal operating parameters with the change of membrane characteristics and draw solution concentration. This study concluded that single-staged full-scale PRO process would be viable from an energy point of view if membranes were manufactured on an industrial scale and with the characteristics of existing membranes on a laboratory scale.

A comparison of three modification methods for polyvinylidene fluoride membrane grafting

Abstract UV-induced covalent bonding, UV-benzophenone (BP) embedding, and ozone-activated grafting methods were respectively used to graft 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) on polyvinylidene fluoride (PVDF) hollow fiber membrane surfaces via orthogonal test. The rejection rate, permeating flux, and pure water flux were chosen as comprehensive evaluation indexes to optimize the modification conditions. The optimal experimental conditions for UV-induced covalent bonding, UV-BP embedding, and ozone-activated grafting methods were obtained. Subsequently, three membranes were prepared by these three methods under their optimal modification conditions to compare their properties. The PVDF-g-AMPS-2 membrane obtained by the UV-BP embedding method exhibited the highest hydrophilicity and lipophobicity, and its water and underwater oil contact angles were respectively 66.0° and 146.6°. Besides, The PVDF-g-AMPS-2 membrane can resist the adhesion of oil with the underwater oil adhesion force of zero. What’s more, the PVDF-g-AMPS-2 membrane possessed the largest pure water flux (544.5 L/(m2·h·bar)), permeation flux (66.5 L/(m2·h·bar)), and recovered flux (205.7 L/(m2·h·bar)). By comparison, UV-BP embedding with simpler procedures can fabricate the AMPS modified PVDF membrane with superior performance, which has better application prospects in industrial scale-up production.

In Vitro Digestion-In Situ Absorption Setup Employing a Physiologically Relevant Value of the Membrane Surface Area/Volume Ratio for Evaluating Performance of Lipid-Based Formulations: A Comparative Study with an In Vitro Digestion-Permeation Model.

The aim of this study is to establish and test an in vitro digestion-in situ absorption model that can mimic in vivo drug flux by employing a physiologically relevant value of the membrane surface area (S)/volume (V) ratio for accurate prediction of oral drug absorption from lipid-based formulations (LBFs). Three different types of LBFs (Type IIIA-MC, Type IIIA-LC, and Type IV) loaded with cinnarizine (CNZ), a lipophilic weak base with borderline permeability, and a control suspension were prepared. Subsequently, a simultaneous in vitro digestion-permeation experiment was conducted using a side-by-side diffusion cell with a dialysis membrane having a low S/V value. During digestion, CNZ partially precipitated for Type IV, while it remained solubilized in the aqueous phase for Type IIIA-MC and Type IIIA-LC in the donor compartment. However, in vitro drug fluxes for Type IIIA-MC and Type IIIA-LC were lower than those for Type IV due to the reduced free fraction of CNZ in the donor compartment. In pharmacokinetic studies, a similar improvement in in vivo oral exposure relative to suspension was observed, regardless of the LBFs used. Consequently, a poor correlation was found between in vitro permeation and areas under the plasma concentration-time curve (AUCoral) (R2 = 0.087). A luminal concentration measurement study revealed that this discrepancy was attributed to the extremely high absorption rate of CNZ in the gastrointestinal tract compared to that across a dialysis membrane evaluated by the in vitro digestion-permeation model, i.e., the absorption of CNZ in vivo was completed regardless of the extent of the free fraction, owing to the rapid removal of CNZ from the intestine. Subsequently, we aimed to predict the oral absorption of CNZ from the same formulations using a model that demonstrated high drug flux by employing the physiologically relevant S/V value and rat jejunum segment as an absorption sink (for replicating in vivo intestinal permeability). Predigested formulations were injected into the rat intestinal loop, and AUCloop values were calculated from the plasma concentration-time profiles. A better correlation was found between AUCloop and AUCoral (R2 = 0.72), although AUCloop underestimated AUCoral for Type IV due to the precipitation of CNZ during the predigestion process. However, this result indicated the importance of mimicking the in vivo drug absorption rate in the predictive model. The method presented herein is valuable for the development of LBFs.

AFM Analysis of Polymeric Membranes Fouling

This work represents a part of a larger work, aimed at evaluating the fouling behavior of different flat polymeric membranes for low-pressure applications when placed in contact with industrial wastewater (IWW). To design and understand the operation of a membrane process it is essential to know the fouling mechanisms. Commercial PVDF and PS membranes were tested under static conditions. The reduction in membrane flux was calculated, before and after the fouling tests. Parameters such as membrane material, pore size, solids concentration, particle size, pH, temperature, flow rate, and pressure were studied to identify the fouling behavior of the membrane. The strong adhesion of organic molecules on the membrane surface develops a resistance to pore blockage which allows a significant decrease in the flow of clean water. It is important to note that membranes of the same material, PVDF, but with different pore size (0.2 and 0.5 mm), and membranes of different materials, PVDF and PS, but with the same pore size (0.2 mm) were tested to study the trend of surface fouling to predict it and/or design surface modifications of the membranes employed. A morphological analysis of the membranes was carried out to understand the fouling mechanism, the fouling times, and the nature of the block that determines the reduction of flow through the membrane itself. Roughness measurements reveal that roughness goes up to 120 minutes of immersing time in wastewater, but after 4 hours it returns to initial value but with a significant decrease of flux to water. Understanding the relationship between flux decline, morphology, and roughness role is key to preventing fouling and studying a valid method to clean the membrane.

UiO-66-NH2/hydrothermal carbon nanocomposite assembled mesh membrane with photocatalytic self-cleaning and antibacterial properties for on-demand oily wastewater separation

The poor wettability, limited permeation flux and unsatisfactory anti-fouling property of oil/water separation membranes significantly hinder their practical application. This study developed a novel UiO-66-NH2/hydrothermal carbon@stainless steel mesh (UiO/HC@SSM) membrane, fabricated through a straightforward dip-coating strategy that offers membrane thickness control. The resulting membrane exhibited superhydrophilic/underwater superoleophobic property and high porosity, enabling gravity-driven separation of emulsified and stratified oil/water mixtures on-demand with high separation efficiency and superior flux. Specifically, UiO/HC@SSM-5 (dip-coating five times) showed ultrahigh permeate fluxes of 51428–56425 L m−2 h−1 for stratified oil/water mixtures separation, and UiO/HC@SSM-10 exhibited interface demulsification and gravity separation ability for emulsified oil/water mixtures with high fluxes of 4050–4504 L m−2 h−1. Notably, UiO/HC nanocomposite endowed the membrane with exceptional photocatalytic self-cleaning and antibacterial activities, effectively addressing both oil and microbial fouling. High-viscosity crude oil fouling can be light-induced decontaminated from the composite membrane surface with superior flux recovery ratio (FRR) up to 97 %. The as-prepared UiO/HC@SSM also exhibited near-complete bacterial inactivation activity after 10 min of visible light irradiation. Encouragingly, UiO/HC@SSM demonstrated superior separation and photocatalytic capabilities compared to UiO@SSM, attributed to the dual promoting role of cost-effective hydrothermal carbon in hydrophilicity and photoelectric properties. Moreover, UiO/HC modified SSM membrane displayed robust chemical and mechanical stability, coupled with superior harsh environments and oil pressure resistances. This membrane, boasting desirable wettability, high permeability, exceptional photocatalytic activity, and excellent stability, offers a reliable solution for treating complex oily wastewater. Additionally, the demulsification and photocatalysis mechanisms of UiO/HC@SSM membrane were examined in depth. This study holds significant potential in advancing the development of novel SSM membranes functionalized with MOF/carbon material, thereby enhancing their practical applications in purifying oily wastewater.

Construction of anti-fouling ceramic tubular membranes with corrugated inner surfaces using DLP 3D printing

The challenge of membrane fouling persistently hinders the advancement of membrane technology. The construction of patterned membrane surfaces is anticipated to mitigate the effects of membrane fouling significantly. In this study, ceramic microfiltration membranes with corrugated patterns were fabricated by 3D printing combined with the dip-coating process. To assess the impact of surface patterning on ceramic membrane performance, we initially compared the pore size and pure water flux between straight and corrugated membrane tubes. Both configurations exhibited similar parameters: a support pore size of approximately 1 μm, a membrane layer pore size of about 110 nm, and a pure water permeance of around 950 L m−2 h−1·bar−1. The corrugated ceramic membranes demonstrated superior anti-fouling properties compared to their straight counterparts during the filtration of nanoparticle suspensions, oil-in-water emulsions, and bacterial suspensions. Specifically, under a nanoparticle suspension concentration of 2000 ppm, a transmembrane pressure of 0.2 MPa, and a flow rate of 1.0 m s−1, the corrugated membrane achieved a stable flux of approximately 1.7 times greater than that of the straight membrane. Furthermore, we explored the effects of surface patterning on fluid dynamics through numerical simulations. The enhanced turbulence dissipation rate in the patterned membrane tubes suggests increased surface turbulence and an improved capacity to remove contaminants. This research offers novel insights into the development of ceramic membranes with enhanced anti-fouling capabilities for water treatment.

Sulfite-activated permanganate pre-oxidation coupled ultrafiltration for treating algae-laden water: Role of calcium ions and in-situ formed MnO2

Membrane fouling caused by algal-derived foulants severely impedes the widespread application of ultrafiltration (UF). Herein, two sulfites (Na2SO3 and CaSO3, S(IV)) were used to activate potassium permanganate (Mn(VII)) as pretreatment to enhance the performance of UF in treating algae-laden water. The results showed that the Mn(VII)/S(IV) system produced MnO2 with abundant hydroxyl groups, which was advantageous for adsorbing algal pollutants. Compared with Mn(VII)/Na2SO3, Mn(VII)/CaSO3 process further increased the aggregation tendency of algal cells, which was due to the Ca2+ bridging effect that promoted the aggregation of MnO2 and algal foulants. S(IV) can activate Mn(VII) to produce free radical (OH and SO4−), and enhance removal of dissolved organic carbon (DOC) and fluorescent organics in coordination with the adsorption of in-situ MnO2. Moreover, the presence of Ca2+ ensured compliance with residual manganese in the treated water. Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory suggested that the Mn(VII)/S(IV) strategy weakened the attractive forces between pollutants and the membrane. FTIR analysis further confirmed that the combined process reduced the accumulation of protein organics on the membrane surface. As a result, the reversible fouling was reduced by 65.3 % and 92.2 %. The in-situ formed manganese oxide altered the structure of the cake layer and delayed the formation of the cake filtration mechanism. Mn(VII)/CaSO3 pretreatment produced a looser cake layer, resulting in a shift of the fouling mechanism towards a single standard blocking. In summary, the novel integrated process can ensure the efficient operation of UF in the purification of algae-laden water.

Reduction of polyketone membranes prepared by thermally induced phase separation with solvent co-extrusion for enhanced fouling resistance

This study utilized solvent co-extrusion technology and NaBH4 reduction to fabricate polyketone (PK) hollow fiber membranes with high water permeance and fouling resistance. Variations in reduction reaction time were explored to assess their impact on chemical composition, morphology, and properties. The results showed that the reduction reaction leads to the conversion of carbonyl groups on the membrane surface to hydroxyl groups, and with prolonged reaction time, the amount of hydroxyl groups on the membrane surface increases to a certain extent. The change in membrane chemical composition enhanced the hydrophilicity, while leaving the membrane morphology, mechanical properties, and separation performance largely unaffected. Static adsorption tests with bovine serum albumin (BSA) and E. coli exhibited distinct fouling behavior. While pristine PK membranes displayed significant BSA adsorption, PK reduction significantly reduced it. Both pristine and reduced PK membranes showed minimal E. coli attachment, likely due to weak interactions. Dynamic filtration tests demonstrated excellent flux recovery for reduced PK membranes, especially after 10 min of reduction, indicating superior fouling resistance with high flux recovery and low irreversible fouling, regardless of foulant type. These findings highlight a straightforward and efficient approach for producing high-performance membranes with exceptional fouling resistance suitable for practical applications.

Electrospun Membranes Based on Quaternized Polysulfones: Rheological Properties-Electrospinning Mechanisms Relationship.

Composite membranes based on a polymer mixture solution of quaternized polysulfone (PSFQ), cellulose acetate phthalate (CAP), and polyvinylidene fluoride (PVDF) for biomedical applications were successfully obtained through the electrospinning technique. To ensure the polysulfone membranes' functionality in targeted applications, the selection of electrospinning conditions was essential. Moreover, understanding the geometric characteristics and morphology of fibrous membranes is crucial in designing them to meet the performance standards necessary for future biomedical applications. Thus, the viscosity of the solutions used in the electrospinning process was determined, and the morphology of the electrospun membranes was examined using scanning electron microscopy (SEM). Investigations on the surfaces of electrospun membranes based on water vapor sorption data have demonstrated that their surface properties dictate their biological ability more than their specific surfaces. Furthermore, in order to understand the different macromolecular rearrangements of membrane structures caused by physical interactions between the polymeric chains as well as by the orientation of functional groups during the electrospinning process, Fourier transform infrared (FTIR) spectroscopy was used. The applicability of composite membranes in the biomedical field was established by bacterial adhesion testing on the surface of electrospun membranes using Escherichia coli and Staphylococcus aureus microorganisms. The biological experiments conducted establish a foundation for future applications of these membranes and validate their effectiveness in specific fields.

One-step fabrication of robust Stenocara beetle-inspired membrane deriving from polyethylene terephthalate (PET) waste for enhancing emulsion separation

The purification of emulsified water from waste oil has become a major research topic. Stenocara beetle-inspired wettable membranes have emerged as separating-efficient designs for purification of oil due to surface energy difference and surface roughness driven demulsification, but they are still suffering from tedious preparation and low robustness. Herein, a one-step electrospinning/electrospraying process was employed to construct Stenocara beetle-like membrane using waste PET and tetrabutyl titanate (TBT) as raw materials for water-in-oil emulsion separation. Specifically, the synchronized deposition process combines electrospinning high-hydrophobic PET fiber membrane and electrospraying superhydrophilic TiO2 particles (superhydrophilic bumps) generated from hydrolysis of TBT on the PET membrane surface, leading to a similar structure to Stenocara beetle. During the separation process, the bumpy superhydrophilic TiO2 particles can capture and aggregate tiny water droplets even though the droplet size is smaller than the membrane pore size. Moreover, this Stenocara beetle-like structure exists both on the surface and interior of the samples, resulting in the boosted demulsification ability and excellent separation efficiency up to 99.8 % and flux as high as 6392 L m-2h−1. Stenocara beetle-like membrane also exhibits strong mechanical properties and strain of the membrane is up to 128.8 %. Even after the friction test, the membrane maintained cycling stability and abrasion resistance with separation flux higher than 3500 L m-2h−1. Overall, this efficient one-step strategy can open up new avenues to fabricate advanced superwetting membranes in the field of emulsion separation.

Anti-fouling underwater superoleophobic membranes based on hierarchical double networks for high efficiency oil–water separation

Oil fouling is a key problem of superwettable oil–water separation membranes because the membranes are inevitably susceptible to varying degrees of oil contamination during the ongoing separation processes, which usually results in a severe impact on separation performance. Consequently, it is a great challenge to construct oil-removal membranes with superior resistance to oil contamination. Herein, we fabricated hierarchical double networks (HDT)-modified porous glass membrane with superhydrophilicity/underwater superoleophobicity. Firstly, a layer of silicone nanofilament (SNF) network bearing tremendous C = C double bonds were fabricated on a porous glass membrane surface by one-step chemical vapor deposition (CVD) using vinyltrichlorosilane (VTCS) as a precursor. Subsequently, the second network layer was constructed by copolymerization of the C = C double bonds on the SNF network and those in sulfobetaine-derived monomer (sulfobetaine methacrylate, SBMA), using N,N′-methylenebisacrylamide (MBA) as the cross-linkering agent. It was observed that the obtained HDT-modified glass membranes displayed excellent superhydrophilicity/underwater superoleophobicity accompanied with superior self-cleaning performance and oil-resistance properties. As a result, the HDT-modified membranes showed high separation flux and high efficiency for both oil/water mixtures (7500 L m−2h−1, above 99.98%) and surfactant-stabilized oil-in-water emulsions (1100 L m−2h−1, above 99.96%) with excellent cyclability. The outstanding advantages with characteristics of excellent oil resistance and superior separation performance enable the HDT-modified glass membrane promising applications in a wide range of industries related to oil–water separations.

Highly thermally conductive multifunctional graphene-based composite membrane for remarkable passive heat dissipation and robust superhydrophobicity

Graphene membrane is considered the preferred item of thermal conductivity material for wearable devices due to its unique flexibility and high thermal conductivity. However, water condensation beads are easily generated on the surface of graphene membranes under high heat and humidity operating conditions. Water condensation beads not only reduce the thermal conductivity of the membrane but may also cause damage to electronic components. To address this issue, an anti-liquid film condensation function can be obtained by spraying an alumina/multi-walled carbon nanotubes/thermoplastic elastomer composite powder (Al2O3/MWCNTs/SEBS) modified by 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (POTS) on graphene membranes. In addition, the obtained composite films have high thermal conductivity (up to 483.1 W/m·K), good superhydrophobicity and antifouling properties, and stable physicochemical properties. The hydrophobicity angle could reach 166 ± 3.3° and the rolling angle 7 ± 2.4°. Under 300 times of bending, it can still maintain its superhydrophobic performance. Therefore, the development of graphene-based composite membrane with high thermal conductivity, hydrophobicity and an excellent water-resistant condensation bead effect is expected to provide a new thermally conductive material solution for heat dissipation in electronic components.

CuFeS2/MXene-Modified Polyvinylidene Fluoride Membrane for Antibiotics Removal through Peroxymonosulfate Activation

In this research, the CuFeS2/MXene-modified polyvinylidene fluoride (PVDF) membrane was prepared to activate peroxymonosulfate (PMS) to remove moxifloxacin (MOX) and its morphology; surface functional groups and hydrophilicity were also studied. The parameters of the catalytic membrane/PMS system were optimized, with an optimal loading of 4 mg/cm2 and a PMS dosage of 0.20 mM. High filtration pressure, alkaline conditions, and impurities in water could inhibit MOX removal. After continuous filtration, the removal efficiency of MOX using the catalytic membrane/PMS system and PVDF membrane was 68.2% and 9.9%, respectively. Batch filtration could remove 87.8% MOX by the extra 10 min contact time between the catalytic membrane and solution. During the filtration process, CuFeS2/MXene on the surface of the catalytic membrane activated PMS to produce SO4•−, HO•, and 1O2, and MOX was removed through adsorption and degradation. Taking humic acid (HA) as the model foulant, reversible fouling resistance in the catalytic membrane/PMS system was 22.8% of the PVDF membrane. The catalytic membrane/PMS system weakened the formation of the cake layer by oxidizing HA into smaller pollutants and followed the intermediate blocking cake filtration model. The novelty of this research was to develop a CuFeS2/MXene–PVDF membrane-activated PMS system and explore its application in antibiotics removal.

Pseudo-bottle-brush decorated thin-film composite desalination membranes with ultrahigh mineral scale resistance.

High water recovery is crucial to inland desalination but is impeded by mineral scaling of the membrane. This work presents a two-step modification approach for grafting high-density zwitterionic pseudo-bottle-brushes to polyamide reverse osmosis membranes to prevent scaling during high-recovery desalination of brackish water. Increasing brush density, induced by increasing reaction time, correlated with reduced scaling. High-density grafting eliminated gypsum scaling and almost completely prevented silica scaling during desalination of synthetic brackish water at a recovery ratio of 80%. Moreover, scaling was effectively mitigated during long-term desalination of real brackish water at a recovery ratio of 90% without pretreatment or antiscalants. Molecular dynamics simulations reveal the critical dependence of the membrane's silica antiscaling ability on the degree to which the coating screens the membrane surface from readily forming silica aggregates. This finding highlights the importance of maximizing grafting density for optimal performance and advanced antiscaling properties to allow high-recovery desalination of complex salt solutions.

A Capillary-Force-Driven, Single-Cell Transfer Method for Studying Rare Cells.

The characterization of individual cells within heterogeneous populations (e.g., rare tumor cells in healthy blood cells) has a great impact on biomedical research. To investigate the properties of these specific cells, such as genetic biomarkers and/or phenotypic characteristics, methods are often developed for isolating rare cells among a large number of background cells before studying their genetic makeup and others. Prior to using real-world samples, these methods are often evaluated and validated by spiking cells of interest (e.g., tumor cells) into a sample matrix (e.g., healthy blood) as model samples. However, spiking tumor cells at extremely low concentrations is challenging in a standard laboratory setting. People often circumvent the problem by diluting a solution of high-concentration cells, but the concentration becomes inaccurate after series dilution due to the fact that a cell suspension solution can be inhomogeneous, especially when the cell concentration is very low. We report on an alternative method for low-cost, accurate, and reproducible low-concentration cell spiking without the use of external pumping systems. By inducing a capillary force from sudden pressure drops, a small portion of the cellular membrane was aspirated into the reservoir tip, allowing for non-destructive single-cell transfer. We investigated the surface membrane tensions induced by cellular aspiration and studied a range of tip/tumor cell diameter combinations, ensuring that our method does not affect cell viability. In addition, we performed single-cell capture and transfer control experiments using human acute lymphoblastic leukemia cells (CCRF-CEM) to develop calibrated data for the general production of low-concentration samples. Finally, we performed affinity-based tumor cell isolation using this method to generate accurate concentrations ranging from 1 to 15 cells/mL.

An unmodified recycled polyethylene terephthalate (PET) nanofibrous membrane for water-in-oil and oil-in-water emulsions separation

A nanofibrous membrane made of unmodified recycled polyethylene terephthalate (rPET) was fabricated by electrospinning using plastic water bottle as raw materials. Using rPET polymer to fabricate membranes may help limit the discharge of plastic bottle waste into the environment and can treat oily wastewater simultaneously, especially emulsions. The variation in the concentration of rPET polymer and the properties of electrospun nanofibers, such as surface morphology and fiber diameter, had a significant impact on both the efficiency of oil droplet capturing and the surface wettability of the membrane. Water-in-oil emulsions and oil-in-water emulsions were separated using the nanofibrous membranes of different concentrations of rPET polymer, and the separation efficiencies at different concentrations of oil, and oil types were measured. The rPET nanofibrous membrane exhibited a water contact angle of 140.1° and was superoleophilic in air and underwater. The membranes exhibited excellent separation performances: >98% separation efficiency and a flux of more than 6500 L m-2 h-1 for water in hexadecane and octane emulsions; >95 % efficiency and a flux of 1509.70 L m-2 h-1 after three separation cycles of water-in-oil emulsions. For oil-in-water emulsions, the separation efficiencies were higher than 95 %, and flux was more than 3525.22 L m-2 h-1 for hexadecane octane and heptane in water emulsions, with an efficiency of >87.9 % and flux of 4186.20 L m-2 h-1 after three separation cycles. Moreover, the as-prepared membrane exhibited high performance of oil-water separation in harsh conditions, including strong acidic, strong basic, and strong salt solutions, with separation efficiencies of more than 98 % and flux of more than 12,700 L m-2 h-1. However, as water accumulated on the membrane surface, absorption and separation efficiency and flux were lowered significantly. This suggests the need to enhance the efficiency of the membrane and reduce the chance of water accumulation on the membrane surface.

#348 Neutrophil membrane-derived nanovesicles deliver IL-37 to repair renal endothelial cells in ischemia‒reperfusion injury

Abstract Background and Aims Renal ischemia‒reperfusion injury (IRI) is one of the most important causes of acute kidney injury (AKI). Interleukin (IL)-37 is a novel anti-inflammatory factor, but its application is still limited by its low stability and delivery efficiency. In recent years, engineered extracellular vesicles (EVs) have attracted substantial attention as an emerging drug delivery system. The aim of this study was to investigate the reparative effect of neutrophil membranes-derived nanovesicle (N-MV)-delivered IL-37 on renal IRI and its mechanism of action. Method The density gradient centrifugation method was used to extract peripheral blood neutrophils from rats, and the differential centrifugation method was used to extract neutrophil membranes. Cell membranes and IL-37 were then extruded with polycarbonate porous membranes with different pore sizes using a mini extruder to prepare IL-37 that was coated with neutrophil membrane (N-MV@IL-37). Subsequently, the physical and chemical properties and in vitro biological functions were identified. The in vivo distribution of N-MV@IL-37 as well as the renal function and inflammatory response in rats were further evaluated in a rat renal IRI model, and the targeting and anti-inflammatory mechanisms of N-MV@IL-37 were further explored. Results N-MV@IL-37 not only enhanced the stability of IL-37 but also targeted endothelial cells via P-selectin glycoprotein ligand-1 (PSGL-1) on neutrophil membrane surfaces. In vitro experiments showed that N-MV@IL-37 inhibited endothelial cell apoptosis and inflammatory factor production and promoted endothelial cell viability and angiogenesis. In the rat renal IRI model, N-MV@IL-37 inhibited renal cell apoptosis and alleviated inflammatory responses, thereby improving renal function in IRI rats. Conclusion N-MVs provide an effective method of delivering IL-37, thereby alleviating the inflammatory response due to renal IRI and repairing renal endothelial cells; these vesicles could be a potential system for the treatment of renal IRI. Meanwhile, N-MVs also provided a drug delivery platform to provide a new strategy for the treatment of other IRI-like diseases.

#753 Targeted anti-IL-1β bacteroides fragilis outer membrane vesicles alleviate inflammatory injury in diabetic nephropathy

Abstract Background and Aims It is accepted that diabetic nephropathy (DN) is not only a disease caused by impaired glucose metabolism, but also a chronic inflammatory disease. The interleukin-1β (IL-1β) plays an important role in inflammation-mediated renal injury in DN. IL-1β blocking therapy can prevent inflammatory cytokine-mediated kidney injury. However, the high cost and systemic side effects of IL-1β antibodies limit its application. Therefore, firstly this study aimed to construct kidney-targeting outer membrane vesicles (OMVs) of Bacteroides fragilis loaded with IL-1β single-chain variable fragment (scFv). These OMVs derived from human commensal non-toxigenic Bacteroides fragilis have been proven to play an immunosuppressive role in the intestine and distant organs. This targeted drug delivery platform built with this as a carrier is expected to relieve kidney inflammation in the development of DN. Methods We recombinantly expressed the scFv based on the Gevokizumab sequence in Escherichia coli, and loaded it into the OMVs derived from Bacteroides fragilis by multiple ultrasounds. The targeting peptide with the sequence (KKEEE)3{Lys(N3)} was connected to the membrane surface through a copper-free catalyzed click chemistry reaction. The package, which consisted of OMVs and the scFv targeting IL-1β in the kidney (OMV-KTP-scFv) was obtained. OMV-KTP-scFv treated in HK-2 cells and healthy mice respectively, and evaluated its in vitro and in vivo drug safety. The concentration of IL-1β scFv in blood and kidney tissues at different time points were measured using streptozotocin (STZ)-induced diabetic mice. DID-labeled OMVs was used for ex vivo infrared imaging of various organs to evaluate the delivery efficiency of the targeted carrier. In vitro, OMV-KTP-scFv was used to prevent inflammation in mouse primary renal tubular epithelial cells induced by high glucose, and in vivo to alleviate kidney injury in STZ-induced diabetic mice. Results We successfully prepared OMV-KTP-scFv and confirmed the co-localization of OMVs, KTP, and scFv using super-resolution microscopy. The prepared OMV-KTP-scFv had high stability, effectively extended the plasma half-life of scFv, and could deliver scFv accurately to the proximal renal tubules. Furthermore, OMV-KTP-scFv also had good safety in vitro and in vivo, and no obvious biotoxicity was found during long-term in vivo administration. In addition, our results show that OMV-KTP-scFv significantly inhibited the expression of inflammatory factors in renal tubular cells of DN, reduced the infiltration of renal interstitial inflammatory cells, and alleviated renal tubular injury. Conclusion Our findings demonstrated that OMVs of Bacteroides fragilis targeting the kidney can deliver the IL-1β scFv to the renal tubulointerstitium and reduce the renal interstitial injury in DN by antagonizing local inflammation.