Polysulfone/amino-silanized poly(methyl methacrylate) dual layer hollow fiber membrane for uremic toxin separation

Efficient uremic toxins adsorption from simulated blood by immobilization of metal organic frameworks anchored Sephadex beads

The current study outlines the removal of Creatinine, p-Cresol sulfate, and Hippuric acid from simulated blood using three new granules: Fe-BTC@Sephadex, Cu-BTC@Sephadex, and Co-BTC@Sephadex. Beads were used to adsorbed toxic chemicals, and the effects of various experimental parameters were examined in the adsorption optimization process. The framework's adsorption isotherms were explained by the application of the Freundlich and Langmuir models. The kinetics of adsorption is represented by a pseudo-first and second-order equation. The morphology and structure of the Fe-BTC@ Sephadex, Co-BTC@ Sephadex, and Cu-BTC@Sephadex beads were investigated using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The adsorption capacities for creatinine were 545.69, 339.76, and 189.88 mg/g for Fe-BTC@ Sephadex, Cu-BTC@ Sephadex, and Co-BTC@ Sephadex, respectively, according to the results; the corresponding adsorption capacities for hippuric acid were 323.78, 206.79, and 68.059 mg/g, and the maximum adsorption capacities for p-Cresol sulfate were 122.65, 71.268, and 40.347 mg/g, respectively. These were, in fact, promising findings that have implications for an industrial-scale transportable artificial kidney.

Regeneration of dialysis solution by dual-layer hollow fiber mixed matrix membrane (DLHF-MMM) incorporated with amine-functionalized mesoporous silica nanoparticles

A large amount of purified water is used in conventional hemodialysis (HD) for treating end-stage kidney disease (ESKD). To minimize the water demand and waste generation, the regeneration of dialysis solution is considered the most efficient control strategy. In this study, an innovative dual-layer hollow fiber (DLHF) mixed matrix membrane (MMM) incorporated with amine-functionalized mesoporous silica nanoparticles (MPS-NPs) was developed to regenerate spent dialysis solution. The fabricated DLHF-MMM configuration enabled the continuous removal of small, medium, and large weight uremic toxins (UTs) through dual mechanisms. The inner layer composed of polyethersulfone (PES) and polyethylene glycol (PEG) rejected medium-large weight UTs (i.e., MW > 500 Da) via the molecular sieving. Meanwhile, the outer layer containing amine-functionalized MPS-NPs effectively removed small weight UTs, such as urea and creatinine. The DLHF-MMM with 6 wt% of amine-functionalized MPS-NPs demonstrated the most favorable characteristics, i.e., high water permeability (298.6 ± 3.2 mL/m2.h.mmHg) and adsorption capacity of urea (523.5 mg/g) and creatinine (28.1 mg/g). Notably, the optimal membrane (DLHF-4) also achieved favorable removal rates from the spent dialysis solution of actual patient, i.e., urea (74.4 %), creatinine (56 %), hippuric acid (16.1 %), and lysozyme (58.7 %, additionally spiked as a mimicking for β-2 microglobulin). These results indicate that the fabricated DLHF-MMM in this study can effectively overcome the challenges posed by the complex matrix components. Overall, the results of this study demonstrate that the DLHF-MMM incorporated with amine-functionalized MPS-NPs is a promising and potential tool for the regeneration of dialysis solution. Furthermore, this approach can contribute to water conservation and reduce the burden on wastewater treatment processes associated with wastewater generated from conventional HD.

Functional Technical Textile-Based Polymer Nanocomposites with Adsorbent Properties of Toxins and Dyes also Have Antibacterial Behavior

This is the first study of non-woven fabrics elaborated by melt-blowing from polymer nanocomposites made of Nylon 6 and nanoclay (Cloisite 20A) modified with an amine (1,4 diaminobutane dihydrochloride). Morphological and physical characteristics, adsorption capacity, and antibacterial properties are presented. From the X-ray diffraction (XRD) results, it was possible to observe a displacement of the signals to other 2θ angles, due to an α to ϒ phase shift. The scanning electron microscopy (SEM) images showed that the mean diameter of fiber decreased as the content of nanoclay increased. The mechanical tests showed that the tear strength force of neat nylon was 1.734 N, but this characteristic increased to 2.135 N for the sample with 0.5% modified nanoclay. The inulin adsorption efficiency of the Nylon 6/C20A 1.5% and Nylon 6/C20A 2% samples at 15 min was 75 and 74%, respectively. The adsorption capacity of Nylon 6/C20A 1.5% and Nylon 6/C20A 2% for methylene blue and methyl orange remained above 90% even after four adsorption cycles. In addition, non-woven fabrics present antibacterial activity against E. coli.

Heparin-Mimetic Chitooligosaccharides-Based Monoliths Obtained from C/W Emulsions: Hemocompatibility and Toxin Removal Ability

Hemoperfusion (HP) is one of the most prominent therapies for treating uremia, hyperbilirubinemia, and acute drug toxicity. The comprehensive performance of currently used porous HP adsorbents needs to be improved due to the impediment to their synthesis strategy. Herein, green carbon dioxide-in-water high internal phase emulsions (C/W HIPEs) were utilized and emulsified with poly(vinyl alcohol) (PVA) for the formation of a heparin-mimetic chitosan oligosaccharides/poly(acrylamide-co-sodium 4-styrenesulfonate) [COS/P(AM-co-SSS)] monolith, which exhibited good mechanical properties, stable swelling performance, hydrophilic properties, anticoagulant effect, and low hemolysis. It showed a strong toxin adsorption capacity (415.2 mg/g for creatinine, 199.3 mg/g for urea, 279.5 mg/g for bilirubin, and 160 mg/g for tetracycline). The adsorption process of porous COS/P(AM-co-SSS) followed the pseudo-second-order kinetic and Langmuir isotherm models. Moreover, the porous materials had a strong electrostatic force on creatinine. The removal of creatinine by simulated in vitro blood perfusion was 80.2% within 30 min. This work provides a green preparation strategy for developing novel HP materials, highlighting their potential application value in blood and environmental purification.

Preparation and surface modification of ultrahigh throughput tannic acid coblended polyethersulfone ultrafiltration membranes for hemodialysis

Low dialysis and blood incompatibility efficiency are key issues to be addressed for polymeric hemodialysis membranes. To improve the comprehensive performance of hemodialysis membranes, polyethersulfone (PES)/tannic acid (TA) coblended ultrafiltration membranes were prepared and modified with a heparin‐like functionalized TA coating. The coblended TA improved the pore structure of the PES ultrafiltration membrane. And it could also undergo π‐π conjugation with the heparin‐like functionalized TA in the modified solution, resulting in a greater abundance of modified groups loaded on the membrane surface and pores close to the surface. The modified coating further improved the membrane performance. The physicochemical properties, solute filtration, and blood compatibility properties of the membrane were tested. The effect of TA on the pore structure of the membrane and the presence of modified layers were demonstrated by morphological and chemical structure analyses. The final modified membrane had an ultrahigh water flux (1053 L/m2·h), improved dialysis performance (BSA retention >99%, Lysozyme clearance >30% and Urea clearance >90%), and excellent hemocompatibility (The hemolysis rate was 1.31%, and APTT, PT, and TT values were increased by 40.8%, 74.2%, and 85.9%, respectively). This study shows that TA has great potential for improving the pore structure of polymeric membranes.

Polymeric Membranes for Biomedical Applications

Polymeric membranes are selective materials used in a wide range of applications that require separation processes, from water filtration and purification to industrial separations. Because of these materials' remarkable properties, namely, selectivity, membranes are also used in a wide range of biomedical applications that require separations. Considering the fact that most organs (apart from the heart and brain) have separation processes associated with the physiological function (kidneys, lungs, intestines, stomach, etc.), technological solutions have been developed to replace the function of these organs with the help of polymer membranes. This review presents the main biomedical applications of polymer membranes, such as hemodialysis (for chronic kidney disease), membrane-based artificial oxygenators (for artificial lung), artificial liver, artificial pancreas, and membranes for osseointegration and drug delivery systems based on membranes.

Open Pore Ultrafiltration Hollow Fiber Membrane Fabrication Method via Dual Pore Former with Dual Dope Solution Phase

Hollow-fiber membranes are widely used in various fields of membrane processes because of their numerous properties, e.g., large surface area, high packing density, mass production with uniform quality, obvious end-of-life indicators, and so on. However, it is difficult to control the pores and internal properties of hollow-fiber membranes due to their inherent structure: a hollow inside surrounded by a wall membrane. Herein, we aimed to control pores and the internal structure of hollow-fiber membranes by fabricating a dual layer using a dual nozzle. Two different pore formers, polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP), were separately prepared in the dope solutions and used for spinning the dual layer. Our results show that nanoscale pores could be formed on the lumen side (26.8-33.2 nm), and the open pores continuously increased in size toward the shell side. Due to robust pore structure, our fabricated membrane exhibited a remarkable water permeability of 296.2 ± 5.7 L/m²·h·bar and an extremely low BSA loss rate of 0.06 ± 0.02%, i.e., a high BSA retention of 99.94%. In consideration of these properties, the studied membranes are well-suited for use in either water treatment or hemodialysis. Overall, our membranes could be considered for the latter application with a high urea clearance of 257.6 mL/min, which is comparable with commercial membranes.

Functionalized Hemodialysis Polysulfone Membranes with Improved Hemocompatibility

The field of membrane materials is one of the most dynamic due to the continuously changing requirements regarding the selectivity and the upgradation of the materials developed with the constantly changing needs. Two membrane processes are essential at present, not for development, but for everyday life-desalination and hemodialysis. Hemodialysis has preserved life and increased life expectancy over the past 60-70 years for tens of millions of people with chronic kidney dysfunction. In addition to the challenges related to the efficiency and separative properties of the membranes, the biggest challenge remained and still remains the assurance of hemocompatibility-not affecting the blood during its recirculation outside the body for 4 h once every two days. This review presents the latest research carried out in the field of functionalization of polysulfone membranes (the most used polymer in the preparation of membranes for hemodialysis) with the purpose of increasing the hemocompatibility and efficiency of the separation process itself with a decreasing impact on the body.

Mixed Matrix Membranes Adsorbers (MMMAs) for the Removal of Uremic Toxins from Dialysate

We developed Mixed Matrix Membrane Adsorbers (MMMAs) formed by cellulose acetate and various sorbent particles (activated carbon, zeolites ZSM-5 and clinoptilolite) for the removal of urea, creatinine and uric acid from aqueous solutions, to be used in the regeneration of spent dialysate water from Hemodialysis (HD). This process would allow reducing the disproportionate amount of water consumed and permits the development of closed-loop HD devices, such as wearable artificial kidneys. The strategy of MMMAs is to combine the high permeability of porous membranes with the toxin-capturing ability of embedded particles. The water permeability of the MMMAs ranges between 600 and 1500 L/(h m2 bar). The adsorption of urea, the limiting toxin, can be improved of about nine times with respect to the pure cellulose acetate membrane. Flow experiments demonstrate the feasibility of the process in a real HD therapy session.

A Novel Generation of Polysulfone/Crown Ether-Functionalized Reduced Graphene Oxide Membranes with Potential Applications in Hemodialysis

Heavy metal poisoning is a rare health condition caused by the accumulation of toxic metal ions in the soft tissues of the human body that can be life threatening if left untreated. In the case of severe intoxications, hemodialysis is the most effective method for a rapid clearance of the metal ions from the bloodstream, therefore, the development of hemodialysis membranes with superior metal ions retention ability is of great research interest. In the present study, synthetic polysulfone membranes were modified with reduced graphene oxide functionalized with crown ether, an organic compound with high metal ions complexation capacity. The physico-chemical characteristics of the composite membranes were determined by FT-IR, Raman, XPS and SEM analysis while their efficiency in retaining metal ions was evaluated via ICP-MS analysis. The obtained results showed that the thermal stability of reduced graphene oxide was improved after functionalization with crown ether and that the presence of the carbonaceous filler influenced the membranes morphology in terms of pore dimensions and membrane thickness. Moreover, the ability of Cu2+ ions retention from synthetic feed solution was up to three times higher in the case of the composite membranes compared to the neat ones.

Co-Adsorptive Removal of Creatinine and Urea by a Three-Component Dual-Layer Hollow Fiber Membrane

The development of wearable artificial kidney demands an efficient dialysate recovery, which relies upon the adsorption process. This study proposes a solution to solve the problem of competitive adsorption between the uremic toxins by employing two adsorptive components in a membrane separation process. Dual-layer hollow fiber (DLHF) membranes, which are composed of a polysulfone (PSf)/activated carbon (AC) inner layer and a PSf/poly(methyl methacrylate) (PMMA) outer layer, were prepared for co-adsorptive removal of creatinine and urea from aqueous solution. The DLHF membranes were characterized in terms of morphological, physicochemical, water transport, and creatinine adsorption properties. The membrane was then subjected to an ultrafiltration adsorption study for performance evaluation. The incorporation of AC in membrane, as confirmed by microscopic and surface analyses, has improved the pure water flux up to 25.2 L/(m² h). A membrane with optimum AC loading (9 wt %) demonstrated the highest maximum creatinine adsorption capacity (86.2 mg/g) based on the Langmuir adsorption isotherm model. In the ultrafiltration adsorption experiment, the membrane removed creatinine and urea with a combined average percent removal of 29.3%. Moreover, the membrane exhibited creatinine and urea uptake recoveries of 98.8 and 81.2%, respectively. The combined action of PMMA and AC in the PSf DLHF membrane has made the adsorption of multiple uremic toxins possible during dialysate recovery.