Heparinized thin-film composite membranes with sub-micron ridge structure for efficient hemodialysis

Polyvinyl Alcohol-Based Membranes: A Review of Research Progress on Design and Predictive Modeling of Properties for Targeted Application

This review provides a comprehensive evaluation of the current state of polyvinyl alcohol (PVA)-based membranes, emphasizing their significance in membrane technology for various applications. The analysis encompasses both experimental and theoretical research articles, with a focus on recent decades, aiming to elucidate the potential and limitations of different fabrication approaches, structure-property relationships, and their applicability in the real world. The review begins by examining the advanced polymeric materials and strategies employed in the design and processing of membranes with tailored properties. Fundamental principles of membrane processes are introduced, with a focus on general modeling approaches for describing the fluid transport through membranes. A key aspect of discussion is the distinction between the membrane performance and process performance. Additionally, an in-depth analysis of PVA membranes in various applications is presented, particularly in environmental fields (e.g., fuel cell, water treatment, air purification, and food packaging) and biomedical domains (e.g., drug delivery systems, wound healing, tissue engineering and regenerative medicine, hemodialysis and artificial organs, and ophthalmic and periodontal treatment). Special attention is given to the relationship between membranes' characteristics, such as material composition, structure, and processing parameters, and their overall performance, in terms of permeability, selectivity, and stability. Despite their promising properties, enhanced through innovative fabrication methods that expand their applicability, challenges remain in optimizing long-term stability, improving fouling resistance, and increasing process scalability. Therefore, further research is needed to develop novel modifications and composite structures that overcome these limitations and enhance the practical implementation of PVA-based membranes. By offering a systematic overview, this review aims to advance the understanding of PVA membrane fabrication, properties, and functionality, providing valuable insights for continued development and optimization in membrane technology.

Dialysis treatment, in vitro, and anticoagulation activity of polysulfone-polyacrylamide based-blend membranes: an experimental study

The majority of treatments are performed with polysulfone (PSf) membranes. The main issue of the PSf membrane is its lack of endothelial function, leading to various processes like platelet adhesion, protein adsorption, and thrombus formation when comes in contact with blood. The crucial aspect in the development of hemodialysis (HD) membrane materials is a biocompatibility factor. This study aims to improve the performance and biocompatibility of PSf membranes by utilizing polyethylene glycol (PEG) as a pore-forming agent and polyacrylamide (PAA) as a multifunctional modifying additive owing to its non-toxic, and biocompatible nature. The formulated HD membranes were characterized using Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and Water Contact Angle (WCA) measurements. The biocompatibility results showed that PSf-PAA membranes reduced the adsorption of bovine serum albumin (BSA) protein, hemolysis process, thrombus formation, and platelets adhesion with improved in vitro cytotoxicity results as well as anticoagulation performance. The protein separation results showed that PSf-PAA membranes were able to reject 90.1% and 92.8% of BSA protein. The membranes also showed better uremic waste clearance for urea (76.56% and 78.24%) and creatinine (73.71% and 79.13%) solutes, respectively. It is conceivable that these modern-age membranes may surpass conventional HD membranes regarding both efficiency and effectiveness.

Advances in Enhancing Hemocompatibility of Hemodialysis Hollow-Fiber Membranes

Hemodialysis, the most common modality of renal replacement therapy, is critically required to remove uremic toxins from the blood of patients with end-stage kidney disease. However, the chronic inflammation, oxidative stress as well as thrombosis induced by the long-term contact of hemoincompatible hollow-fiber membranes (HFMs) contribute to the increase in cardiovascular diseases and mortality in this patient population. This review first retrospectively analyzes the current clinical and laboratory research progress in improving the hemocompatibility of HFMs. Details on different HFMs currently in clinical use and their design are described. Subsequently, we elaborate on the adverse interactions between blood and HFMs, involving protein adsorption, platelet adhesion and activation, and the activation of immune and coagulation systems, and the focus is on how to improve the hemocompatibility of HFMs in these aspects. Finally, challenges and future perspectives for improving the hemocompatibility of HFMs are also discussed to promote the development and clinical application of new hemocompatible HFMs.

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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.

One step preparation of multifunctional poly (ether sulfone) thin films with potential for wound dressing

The increasing demand for higher-quality medical care has resulted in the obsolescence of traditional biomaterials. Medical care is currently transitioning from an era depending on single-functional biomaterials to one that is supported by multifunctional and stable biomaterials. Herein, long-lasting multifunctional poly(ether sulfone) thin films (MPFs) containing heparin-mimic groups and a quaternary ammonium compound (QAC) were prepared via semi-interpenetrating polymer network (SIPN) strategy. The MPFs, with rough surface and inner finger-like macrovoid, had better hydrophilicity and anti-protein fouling ability, as revealed by scanning electron microscopy (SEM), atomic force microscope (AFM) and water contact angle (WCA) and protein adsorption tests. The results of platelet adhesion and activation, and clotting time confirmed that the hemocompatibility of the MPFs was significantly improved. From cell culture and germ-culture test, it was noted that the overall trend of human umbilical vein endothelial cell (HUVEC) proliferation was enhanced by a combination of heparin-mimic groups and QAC, whereas the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was significantly prohibited. In addition, the MPFs were capable of modulating the expression level of basic fibroblast growth factor (bFGF) and transforming growth factor-beta1 (TGF-β1) in fibroblast, which was beneficial to controlling the formation of hypertrophic scar. In summary, the MPFs had potential to be used in the field of wound management and the study might help guide the design of surface structure of wound dressing.

Manufacturing and Separation Characteristics of Hemodialysis Membranes to Improve Toxin Removal Rate

With the recently growing interest in health care, hemodialysis is being performed not only to treat patients with renal disease but also to improve blood circulation. At present, filters used for hemodialysis are manufactured only in certain countries, and all other countries must rely on imports. In this study, polyethersulfone (PES), which has excellent blood compatibility, was used as the main material to develop hemodialysis membranes for hemodialysis filters, and these hemodialysis membranes were prepared by adding a hydrophilic polymer, polyvinylpyrrolidone (PVP), and varying the type of nonsolvent during the manufacturing process to improve the toxin removal rate and biocompatibility. The addition of PVP was confirmed through attenuated total reflection Fourier transform infrared (ATR-FTIR), and the structure of the membranes depending on the nonsolvent was analyzed through scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. The contact angle results indicated that the hydrophilicity of the membrane surface was improved as the concentration of PVP increased. The results of the toxin filtration efficiency experiment using urea, creatinine, and bovine serum albumin (BSA) confirmed removal rates of 58.8% and 56.87%, respectively, and a protein loss of less than 8%. Also, cell viability was over 90% at the PVP concentration of 2% or higher. A preliminary study was conducted on the improvement of toxin filtration efficiency and the development potential of these hemodialysis membranes with excellent biocompatibility.

Hierarchical Shish-Kebab Structures Functionalizing Nanofibers for Controlled Drug Release and Improved Antithrombogenicity

The functionalization of the fibrous scaffolds including drug loading and release is of significance in tissue engineering and regenerative medicine. Our previous results have shown that the shish-kebab structure-modified fibrous scaffold shows a completely different microenvironment that mimics the topography of the collagen fibers, which interestingly facilitates the cell adhesion and migration. However, the functionalization of the unique structure needs to be further investigated. In this study, we modified the heparin-loaded fiber with a shish-kebab structure and tuned the kebab structure as the barrier for the sustained release of heparin. The introduction of the kebab structure increases the diffusion energy barrier by extending the diffusion distance. Moreover, the discontinued surface topography of the shish-kebab structure altered the surface chemistry from hydrophobic for the original poly(ε-caprolactone) (PCL) nanofibers to hydrophilic for the PCL nanofibers with the shish-kebab structure, which might have inhibited the activation of fibrinogen and thus improved the anticoagulant ability. This synergistic effect of heparin and the kebab structure significantly promotes the endothelial cell affinity and antithrombogenicity. This method might be a viable and versatile drug delivery strategy in vascular tissue engineering.

Hydrophilized Ultrafiltration Membranes Synthesized from Acrylic Acid Grafted Polyethersulfone for Downstream Processing of Therapeutic Insulin and Cobalamin

The present study focuses on synthesis of novel high-performance acrylic acid (AA) grafted polyethersulfone (PES) ultrafiltration (UF) membranes for purification of small therapeutic biomolecules such as urea, insulin, and cobalamin. The membranes were indigenously synthesized by adding polyethylene glycol (PEG) of 6 kDa M.Wt. as a pore former and subsequent grafting of AA using 2 to 6 wt.% concentrations under UV-induced photo grafting. Scanning electron microscopy reveals that the PEG additive profoundly influences the pore density on the membrane surface. FTIR spectra confirm the graft polymerization of AA with the PES substrate. Separation performance of the grafted membranes was evaluated to establish the trade-off between the degree of grafting and MWCO. From the experimental results, the pure water flux (PWF) of 6% grafted PES membrane was enhanced from 8.5 (PES [0] [6]) to 18.20 l m^-2 h^-1 (PES [6 +] [6]) in the presence of PEG pore former, respectively. The grafting concentration window of 2-6% resulted in selective membranes to altogether remove uremic toxins into the permeate with retention of high molecular size proteins. Hence, 5 and 6 wt.% AA grafted membranes exhibited > 90% rejection for insulin and cobalamin biomolecules along with 24.5 and 23.8 l m^-2 h^-1 bar^-1 permeability towards urea, respectively. The process results correlate well with the MWCO values of membranes ranging from 1 to 10 kDa. This work provides the efficacy of these grafted membranes for potential application in the downstream processing of therapeutic biomolecules such as insulin and cobalamin.

Cellulose acetate-polyvinyl alcohol blend hemodialysis membranes integrated with dialysis performance and high biocompatibility

Hemodialysis considered as therapy of end-stage renal disease (ESRD) for the separation of protein and uremic toxins based on their molecular weights using semi-permeable membranes. Cellulose Acetate (CA) hemodialysis membrane has been widely used in the biomedical field particularly for hemodialysis applications. The main issue of CA membrane is less selectivity and hemocompatibility. In this study, to enhance the filtration capability and biocompatibility of CA hemodialysis membrane modified by using Polyvinyl Alcohol (PVA) and Polyethylene Glycol (PEG) as additives. CA-PVA flat sheet membranes were cast by phase inversion method, and separation was done by dead-end filtration cell. The synthesized membranes were described in terms of chemical structure using Fourier Transform Infrared Spectroscopy (FTIR) and morphology by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), pure water flux, solute permeation, and protein retention. Biocompatibility of the membranes was tested by the platelet adherence, hemolysis ratio, thrombus formation, and plasma recalcification time. SEM images exposed that the CA-PVA membrane has a uniform porous structure. 42.484 L/m² h is the maximum pure water flux obtained. The CA-PVA rejected up to 95% of bovine serum albumin (BSA). A similar membrane separated 93% of urea and 89% of creatinine. Platelet adhesion and hemolysis ratio of casted membranes were less than the pure CA membrane. Increased clotting time and less thrombus formation on the membrane's surface showed that the fabricated membrane is biocompatible. CA-PVA hemodialysis membranes are more efficient than conventional reported hemodialysis membranes. It revealed that CA-PVA is high performing biocompatible hemodialysis membrane.