Nitrate removal from contaminated groundwater by micellar-enhanced ultrafiltration using a polyacrylonitrile membrane with a hydrogel-stabilized ZIF-L layer.

Contamination of groundwater by nitrate from intensive agriculture is a serious problem globally. Excessive fertilization has led to nitrate contamination of the Coastal Aquifer in Israel. Here we report the efficient removal of nitrate from contaminated groundwater by micellar-enhanced ultrafiltration (MEUF) using a specially tailored membrane. Graft polymerization with hydrophilic poly(methacrylate) and incorporation of porous zeolitic imidazole framework ZIF-L nanoparticles imparted antifouling properties to the membrane. The resulting modified membrane showed high water permeance (82.2 ± 1.7 L·m-2·h-1·bar-1). The efficiency of nitrate removal by MEUF was tested using cetylpyridinium chloride as a surfactant in nitrate-contaminated groundwater collected from the Coastal Aquifer of Israel. The membrane reduced nitrate levels from 40-70 to levels of 6.8-29.5 mg·L-1, depending on the groundwater composition; further reduction to 6.1-24.1 mg·L-1 with complete surfactant rejection was achieved via two-stage membrane filtration, which showed high permeate flux (between 32.1 ± 0.9 and 45.9 ± 0.6 L·m-2·h-1) at 2 bar. The membrane maintained stable separation performance during multiple cycles, and the flux recovery ratio was >93 %. Nitrate concentrations fell well below the acceptable limit for drinking water, allowing the treated water to be used without restriction. Overall, the membrane has the potential to allow efficient removal by MEUF of nitrate from contaminated groundwater.

Surface-Functionalized Poly(Ether Sulfone) Composite Hollow Fiber Membranes with Improved Biocompatibility and Uremic Toxins Clearance for Bioartificial Kidney Application.

Bioartificial kidney (BAK) is attracting the focus of the research community. In this study, the efficacy of surface-functionalized poly(ether sulfone)-TPGS-graphene oxide composite hollow fiber membranes as a promising material for the single extracorporeal unit for BAK application was evaluated. The cytotoxicity was examined using human primary renal proximal tubular epithelial cells (hPTCs), and the removal of uremic toxins (urea, creatinine, phosphate, and lysozyme) from the toxin-spiked goat blood was measured. The surface-functionalized polymer composite membranes acted as a biocompatible material for attachment and proliferation of hPTCs, which was confirmed by microscopy studies, proliferation, and activity assays. The functional activity of these renal cells over this biocompatible membrane was also maintained. Remarkably, the functionalized composite membranes showed removal of urea (46.4 ± 3.5%), creatinine (52.2 ± 3.9%), phosphate (35.5 ± 2.7%), and lysozyme (11.2 ± 0.8%) from the toxin-spiked goat blood. Therefore, these obtained results showed that the surface-functionalized poly(ether sulfone)-TPGS-graphene oxide composite hollow fiber membranes are suitable for BAK application.

Polyethersulfone-carbon nanotubes composite hollow fiber membranes with improved biocompatibility for bioartificial liver.

Carbon nanotubes (CNTs) blended hollow fiber membranes (HFMs) are a promising new material in the area of biomedical engineering because they simultaneously provide tunable hydrophilicity along with selective permeability. In the present study, composite polyethersulfone (P) HFMs were fabricated using d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS or T) as compatibilizer, and carboxylated multiwalled CNTs (MWCNTs or C) as filler. The amount of MWCNTs was optimized for the improved hemocompatibility, cell viability, and cellular functionality. An optimum was found with the composte HFMs (PTC-2), where MWCNTs were used at concentration of 0.030 wt.%, as it exhibited improved compatibility with human blood. Further, these PTC-2 HFMs showed enhanced liver (HepG2) cells growth with the enhanced cell functional activities, mainly albumin secretion and glucose consumption. These developed composite membrane can act as a membrane material for liver cell bioreactor and bioartificial liver development because of their 3D scaffold like characteristic which enables cell growth, and selective permeability which helps in immunoisolation.

Efficient separation of biological macromolecular proteins by polyethersulfone hollow fiber ultrafiltration membranes modified with Fe3O4 nanoparticles-decorated carboxylated graphene oxide nanosheets.

The separation of biological macromolecules, e.g., proteins, using ultrafiltration membranes in the biotechnology, food and pharmaceutical industries has gained the significant attention of the research community. In this work, iron oxide nanoparticles-decorated carboxylated graphene oxide nanosheets (Fe3O4/cGO nanohybrid) were synthesized and incorporated in polyethersulfone (PES) hollow fiber ultrafiltration membranes (HFMs) and the resulting modified membranes were evaluated for the separation of proteins, namely lysozyme, trypsin, pepsin, human serum albumin, γ-globulin and fibrinogen. The physicochemical properties, mainly mechanical strength, hydrophilicity, porosity, pore size, and surface roughness were found to be favorable for the modified HFMs. These properties helped the composite membranes (HFMs modified with 0.1 wt% Fe3O4/cGO nanohybrid) in achieving remarkably high pure water flux (110.0 ±â€¯3.8 L/m2 h) and as high as 97.8% flux recovery. PES-Fe3O4/cGO composite HFMs showed significantly high rejection of lysozyme (92.9 ±â€¯1.3%), trypsin (94.5 ±â€¯1.1%), pepsin (96.9 ±â€¯1.2%), human serum albumin (99.5 ±â€¯0.5%), human γ-globulin (100%), and human fibrinogen (100%). These composite HFMs also maintained their efficacious rejection performance during the long-term studies. Therefore, the HFMs modified with Fe3O4/cGO nanohybrid are the potential membranes for the efficient separation of biomolecules, particularly proteins in the biotechnology, food and pharmaceutical industries.

Hydrophilic ZIF-8 decorated GO nanosheets improve biocompatibility and separation performance of polyethersulfone hollow fiber membranes: A potential membrane material for bioartificial liver application.

The hydrophobic nature of zeolitic imidazole framework-8 (ZIF-8) nanoparticles restricts their use as additives in hollow fiber membranes (HFMs) for biomedical applications. In this study, hydrophilic ZIF-8 decorated graphene oxide nanosheets (ZGs) were synthesized and used as additives (0-1 wt%) in polyethersulfone (P) HFMs with the aim of improving the biocompatibility and separation performance so as to make the ZGP HFMs suitable for bioartificial liver (BAL) application. Elemental mapping and Fourier transform infrared studies confirmed the efficacious incorporation of ZG nanohybrids in the ZGP HFMs, which resulted in their improved hydrophilicity. The remarkably improved biocompatibility was experimentally demonstrated for the ZGP HFMs, which also were antioxidative and hemocompatible. There was a significantly high attachment and proliferation of HepG2 cells on these HFMs, and they showed remarkably high urea synthesis and albumin secretion. Further, the ZGP HFMs showed high ultrafiltration coefficient (392.2 ±â€¯26.5 mL/h/m2/mm Hg), high flux recovery ratio (84.3%), low flux reduction (15.7%), and desirable molecular weight cutoff (125-135 kDa). Thus, these results experimentally demonstrated that the hydrophilic ZG nanohybrids improve the desirable properties of ZGP HFMs making them a potential biocompatible material for biomedical applications including BAL application.

Extracellular matrix-coated polyethersulfone-TPGS hollow fiber membranes showing improved biocompatibility and uremic toxins removal for bioartificial kidney application.

In this study, L-3, 4-dihydroxyphenylalanine and human collagen type IV were coated over the outer surface of the custom-made hollow fiber membranes (HFMs) with the objective of simultaneously improving biocompatibility leading to proliferation of human embryonic kidney cells-293 (HEK-293) and improving separation of uremic toxins, thereby making them suitable for bioartificial kidney application. Physicochemical characterization showed the development of coated HFMs, resulting in low hemolysis (0.25 ±â€¯0.10%), low SC5b-9 marker level (7.95 ±â€¯1.50 ng/mL), prolonged blood coagulation time, and minimal platelet adhesion, which indicated their improved human blood compatibility. Scanning electron microscopy and confocal laser scanning microscopy showed significantly improved attachment and proliferation of HEK-293 cells on the outer surface of the coated HFMs, which was supported by the results of glucose consumption and MTT cell proliferation assay. The solute rejection profile of these coated HFMs was compared favorably with that of the commercial dialyzer membranes. These coated HFMs showed a remarkable 1.6-3.2 fold improvement in reduction ratio of uremic toxins as compared to standard dialyzer membranes. These results clearly demonstrated that these extracellular matrix-coated HFMs can be a potential biocompatible substrate for the attachment and proliferation of HEK-293 cells and removal of uremic toxins from the simulated blood, which may find future application for bioartificial renal assist device.

Functionally coated polyethersulfone hollow fiber membranes: A substrate for enhanced HepG2/C3A functions.

Hollow fiber membrane (HFM) based liver assist systems are a life-saving bridge for patients until a donor organ is available for transplantation or until liver regeneration. However, liver cell attachment and functional maintenance on HFM surface is a major challenge in bio-artificial liver (BAL) support systems. In the present study, novel glutaraldehyde (GTA)-crosslinked gelatin (gel)-coated polyethersulfone (X-gel-PT) HFMs were manufactured using triple orifice spinneret by the dry-wet spinning method. HFMs were characterized for morphology, outer surface roughness, hydrophilicity, tensile strength, thermal stability, BET surface area and pore volume measurements, permeability and rejection. Fourier transform infrared spectroscopy, and transmission electron microscopy confirmed the GTA-crosslinked gel-coating in the X-gel-PT HFMs, which provided the desirable extracellular matrix-like environment to the HepG2/C3A cells. The results of in-vitro hemocompatibility tests showed the better suitability of the developed HFMs for the blood-contact application. X-gel-PT HFMs showed significantly better cellular attachment and proliferation of HepG2/C3A cells on day 3 and 6, as shown by scanning electron and confocal microscopy. Significantly high urea synthesis and albumin secretion seen indicated the improved functional and metabolic activity of HepG2/C3A cells. Thus, the developed X-gel-PT HFMs is a suitable substrate for the hepatocyte culture, mass culture, and development of BAL support system.

Graphene oxide-doping improves the biocompatibility and separation performance of polyethersulfone hollow fiber membranes for bioartificial kidney application.

HYPOTHESIS: Graphene oxide (GO)-doping in polyethersulfone hollow fiber membranes (PES HFMs) improves the biocompatibility and separation performance for bioartificial kidney (BAK) application. EXPERIMENTS: GO was doped in PES HFMs. The physicochemical characterization of the developed HFMs was carried out. The biocompatibility tests including hemocompatibility and cytotoxicity tests, and separation experiments including uremic toxins clearance were performed. FINDINGS: GO-doping resulted in low hemolysis (0.37 ±â€¯0.15%), prolonged coagulation times, and low SC5b-9 marker level (6.84 ±â€¯1.7 ng/mL), i.e., significantly improved hemocompatibility of GP HFMs. The monolayer attachment and improved proliferation of kidney cells on the outer surface of GP HFMs were achieved. GO-doping significantly enhanced the separation performance, i.e., high pure water permeability (154 ±â€¯3 mL/m2/h/mmHg) was measured, and similar solute rejection profile as that of the commercial dialyzer membranes was recorded. The clearance of urea, creatinine and phosphorous from the simulated blood was measured to be almost 1.6 to 3.3 times higher than that measured for the commercial membranes. Thus, these results indicated that the GO-doping remarkably improved the performance of the developed GP HFMs thereby making them a potential membrane material for the BAK application.

Three-dimensional multiscale fiber matrices: development and characterization for increased HepG2 functional maintenance for bio-artificial liver application.

The development of a cell-growth substrate that provides a nature-like microenvironment, promotes cell adhesion, and maintains the cells' functional activities is a research focus in the field of tissue engineering. In the present study, three-dimensional micro-nano multiscale fiber-based substrates were developed by depositing biocompatible polycaprolactone (PCL)/PCL-Chitosan (C)/PCL-C-Gelatin (G) electrospun nanofibers (NFs) on the outer surface of hollow fiber membranes (HFMs) in one step. A comparison study with regard to physico-chemical characterization, hemocompatibility, cytotoxicity, and cellular functionality was performed with the developed matrices. The PCL-C-G NFs-deposited HFMs-based matrix showed superior hemocompatibility for blood-contact applications. The cytotoxicity of these matrices was found to be minimal. HepG2 cells exhibited an exceptionally robust adherence and proliferated growth on the matrix with the formation of characteristic multi-cellular spheroids. Furthermore, cell functional activities such as albumin secretion, urea synthesis, and cytochrome P450 specific activity were measured for the developed matrices. The developed three-dimensional multiscale fibers-based matrix can be a potential membrane for bioreactor and bio-artificial liver applications.

Improved hemodialysis with hemocompatible polyethersulfone hollow fiber membranes: In vitro performance.

We show that addition of nanozeolite (NZ) and vitamin E D-α-Tocopherol polyethylene glycol succinate (TPGS or T) considerably improves the performance of polyethersulfone (PES or P) hollow fiber membrane (HFM) for hemodialysis. Nanocomposite HFMs were manufactured using PES as a polymer, TPGS as an additive and NZ as a filler to give a composite membrane called PT-NZ. HFMs were spun by dry-wet spinning principle based on liquid-liquid phase separation. TPGS and NZ were successfully incorporated in HFMs, as confirmed by EDX elemental mapping. The resultant PT-NZ HFMs had improved hemocompatibility: lower percent hemolysis (0.28% in batch mode and 0.32% in continuous mode), lower platelet adhesion, higher coagulation time and lower protein adsorption (16.34 µg/cm2 ), compared with P, PT, and commercial (F60S) HFMs. The ultrafiltration coefficient of PT-NZ HFM-based module (274.59 mL/m2 /h/mmHg) was ∼1.5-times higher than that of F60S membranes (151.67 mL/m2 /h/mmHg), and the solute rejection of both the membranes was comparable. The toxin clearance performance of lab-scale PT-NZ HFM-based hemodialyzer with uremic toxin spiked goat blood was remarkably higher (five times) than that of F60S. Hence, the synthesized PT-NZ HFMs are a potentially attractive membrane material for hemodialysis application, particularly due to decreased treatment time and minimal side reactions. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1286-1298, 2018.

Lactobionic acid-functionalized polyethersulfone hollow fiber membranes promote HepG2 attachment and function.

Surface modification of polyethersulfone hollow fibers, which are important in bio-artificial liver, is increasingly used to improve biocompatibility and promote the adhesion and proliferation of hepatocytes resulting in improved cell functionality. Hepatocytes are anchorage-dependent cells, and membrane surface modification enhances the hepatic cell adhesion and proliferation. Specific interaction of the asialoglycoprotein receptor on hepatocyte cell surfaces with a galactose moiety enhances the attachment of the cells on a biocompatible substrate. In this study, the outer surface of the polyethersulfone (P) hollow fiber membranes (HFMs) was chemically modified by covalent coupling with lactobionic acid (LBA). The energy dispersive X-ray spectrometry elemental mapping, attenuated total reflectance-Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy confirmed the LBA-coupling on the outer surface of P-LBA HFMs. Hemocompatibility study indicated the suitability of the modified membranes with human blood. These membranes showed remarkably improved biocompatibility with human primary mesenchymal stem cells and HepG2 cells. Characteristic multi-cellular spheroids of HepG2 cells were observed under scanning electron and confocal microscopy. HepG2 cell functional activity was measured by quantifying the urea synthesis, albumin secretion and glucose consumption in the culture media, which indicated the improved HepG2 functions. These experimental results clearly suggest the potentiality of these LBA-modified P HFMs as a suitable biocompatible substrate for promoting HepG2 attachment and function leading to their application in bioreactors and bio-artificial liver devices.

Graphene oxide nanosheets and d-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS) doping improves biocompatibility and ultrafiltration in polyethersulfone hollow fiber membranes.

Novel graphene oxide (G)-and d-α-Tocopheryl polyethylene glycol 1000 succinate (T)-doped polyethersulfone (P) hollow fiber membranes (GTP HFMs) were efficiently prepared. GTP HFMs were found to be a desirable biocompatible substrate for attachment and proliferation of human embryonic kidney-293 (HEK-293) cells. Significantly high porosity (94.58±1.1%), low contact angle (61.1±2.5°), low hemolysis (0.58% in batch mode and 0.64% in continuous mode), low terminal complement complex activation (SC5b-9 marker level ∼6.73ng/mL), prolonged blood coagulation time, and low platelet adhesion were measured for GTP HFMs indicating the superior suitability of GTP HFMs for blood-contact applications. Further, SEM and confocal laser microscopy studies showed the significantly high HEK-293 cells attachment and proliferation on GTP HFMs which was corroborated by results of glucose consumption analysis and MTT cell proliferation assay. High ultrafiltration coefficient (110±3mL/m2/h/mmHg), and albumin solute rejection (94.87±0.5%) were also measured for GTP HFMs. Thus, these results clearly indicated that the synergistic effect of additives improved the biocompatibility and ultrafiltration in GTP HFMs. The developed GTP HFMs can potentially be used for simultaneous/sequential cells attachment and proliferation, and ultrafiltration applications such as the bioartificial kidney.