Recent advancement challenges with synthesis of biocompatible hemodialysis membranes

Heparin and heparin-like modifications in hemodialysis membranes: Current innovations and future directions

Heparinized hemodialysis membranes represent a significant advancement in improving the biocompatibility and anticoagulant properties of dialysis treatments. This review explores the current challenges and innovations in developing these membranes, focusing on the incorporation of heparin and heparin-like substances to reduce protein adsorption, platelet adhesion, and clot formation. The methods for heparin immobilization, including covalent bonding, layer-by-layer assembly, and blending, offer promising results in enhancing membrane performance. However, issues such as long-term stability, large-scale production, and cost-effectiveness remain critical barriers to their widespread adoption. The review also highlights the role of surface activation techniques and nanotechnology in improving the functionality of heparinized membranes. Advanced methods like plasma treatment and polymer grafting provide better heparin attachment, while nanomaterial integration allows for improved blood compatibility and controlled heparin release. Despite these innovations, challenges such as heparin degradation, uneven coating, and the complexity of scaling up remain unresolved. Future research should focus on optimizing heparin distribution, enhancing durability, and making the production process more cost-efficient. This paper outlines potential interdisciplinary approaches, such as bioinspired materials and nanotechnology applications, to address these challenges and pave the way for next-generation hemodialysis membranes that are safer, more effective, and more accessible.

Improving the bioactivity of cellulose acetate hemodialysis membranes through nanosilver modification

The effectiveness and safety of hemodialysis can be hindered by protein accumulation, mechanical instability of membranes and bacterial infection during the dialytic therapy. Herein, we show that cellulose acetate membranes modified with the low-fouling polymers (namely polyvinylpyrrolidone and polyethylene glycol), followed by the in situ reduction of different densities of silver oxide(I) nanoparticles, can effectively address these limitations. These improvements comprise the enhanced resistance to the protein fouling, improved antimicrobial capabilities against S. aureus, increased selectivity, and thermal stability and mechanical strength. The nano-enhanced membranes showed an improved albumin rejection rate of approximately 90 %, and the creatinine clearance rate ranged between 90 and 94 %. Our findings demonstrate that nanosilver-modified membranes can be readily prepared from precursor solutions to act as robust, biocompatible, and hydrophilic hemodialysis membranes with controlled bacteriostatic potential, antifouling properties and high toxin clearance.

Biological testing unification for hemodialysis membranes evaluation: A step towards standardization

Current hemodialysis treatments can cause adverse effects, many of which are linked to the membranes used in the process. These issues are being addressed through new materials and technologies, making it urgent to establish minimum guidelines for evaluating such membranes. This review proposes standardizing the biological tests and variables to evaluate the performance of new membranes, aiming to replicate hemodialysis conditions closely. The tests were categorized into protein adsorption, protein transmission, platelet adhesion, platelet activation, blood coagulation times, hemolysis, complement activation, and cytotoxicity. For protein adsorption, static tests are recommended as an initial step to rule out membrane adhesion, followed by dynamic tests that must be conducted using a crossflow system (>250 mL/min flow) and a solution mimicking real conditions (BSA, lysozyme, trypsin, pepsin, creatinine, urea, albumin, fibrinogen, and γ-globulin). Protein transmission tests must employ dynamic conditions, using human blood or platelet-rich plasma for a minimum time of 3.5 h. Complement activation should be tested using human blood and ELISA assays to detect C3, C5 TCC, and SC5b-9. Blood coagulation times (APTT, TT, FT, TCT, and TAT) should be measured with platelet-poor and platelet-rich plasma. Hemolysis tests should transition from water bath to continuous mode for at least 3.5 h. Cytotoxicity tests should compare the MTT assay with other methods (Alamar Blue, Lactate Dehydrogenase Assay, Flow Cytometry, or Trypan Blue Exclusion Test) and use different cell types for comprehensive validation. By implementing these minimum biological tests, membrane evaluations would more accurately reflect the real-world applications, ensuring biocompatibility, effectiveness, and efficiency.

Impact of pH-dependent dynamics of human serum proteins on dialysis membranes: Cryptographic structure assessment, synchrotron imaging of membrane-protein adsorption, and molecular docking studies

Proteins are fundamental to biochemical processes and critical in hemodialysis. This study investigates the impact of pH on human serum albumin (HSA), fibrinogen (FB), and transferrin (TRF) interactions with polyarylethersulfone (PAES) hemodialysis membranes. A multi-method approach was utilized, including protein crystallography for structural insights, hydration layer analysis to explore solvation and interaction potentials, molecular docking using AutoDock 4.0 for binding affinity simulations, and in-situ X-ray synchrotron SR-μCT imaging to observe protein deposition dynamics. Molecular docking revealed that PAES demonstrated superior binding energies and interaction patterns with FB and TRF compared to cellulose triacetate (CTA), facilitated by specific hydrogen bonding within a water shell. CTA displayed weaker, hydration-sensitive interactions varying with pH. Imaging studies indicated that FB showed higher adsorption at pH 6 than at pH 7.2, predominantly in the middle membrane regions. Similarly, HSA and TRF exhibited increased adsorption at pH 6, suggesting a stronger affinity under acidic conditions. Mixed protein solutions also indicated higher adsorption at pH 6, emphasizing an increased risk of membrane fouling. These findings highlight the crucial role of pH in modulating protein-membrane interactions and enhancing the efficacy of hemodialysis. A deeper understanding of hydration environments and their effects on protein binding affinities provides valuable insights for optimizing membrane design and performance. Clinically, this research suggests that fine-tuning pH during hemodialysis could mitigate protein fouling on membranes, thereby improving procedural efficiency and potentially leading to better patient outcomes through enhanced dialysis effectiveness.

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.

Bioinspired shape-changing nanofiber dressings for intelligent wrapping and promoting healing of superficial wounds

The use of dressings in clinical settings is common for the purpose of wound wrapping and creating an optimal microenvironment to enhance the healing process. Proper coverage of wounds with dressings serves as the fundamental basis for effective wound healing. Unfortunately, non-standard coverage by hands can cause pain and secondary damage to patients, while slow manual application during treatment of extensive burns may increase the risk of wound infection. Herein, drawing inspiration from the microstructure and hygroscopic deformation observed in pine cones, we propose a polyvinyl alcohol/polysulfone (PVA/PSF) smart dressing. This bioinspired smart dressing exhibits rapid bending deformation under high moisture condition, allowing easy adjustment of bending amplitude, speed, and direction. Moreover, the smart dressing is capable of rapid bending and autonomous wrapping around "artificial wounds" on a doll's body, as well as fitting irregularly shaped "hand wounds" and extensive "arm wounds" on human subjects. By integrating two layers into one dressing design, we endow it with dual functionality: The hygroscopic PVA layer facilitates transversal liquid transport to effectively reduce exudate accumulation in the wound bed while maintaining proper moisture levels; meanwhile, the highly hydrophobic PSF layer repels various aqueous solutions to protect against external contaminants. In vivo results confirm that this multifunctional smart dressing promotes collagen synthesis and accelerates angiogenesis for accelerated wound healing. We believe that this innovative multifunctional approach to wound management will provide valuable insights into wound healing therapy.

Simulation-based assessment of zwitterionic pendant group variations on the hemocompatibility of polyethersulfone membranes

In the realm of hemodialysis, Polyethersulfone (PES) membranes dominate due to their exceptional stability and mechanical properties, capturing 93% of the market. Despite their widespread usage, the hydrophobic nature of PES introduces complications in hemodialysis, potentially leading to severe adverse reactions in patients with end-stage renal disease (ESRD) through protein fouling. Addressing this issue, our study focused on enhancing hemocompatibility by modifying PES surfaces with zwitterionic materials, known for their hydrophilicity and biological membrane compatibility. We investigated the functionalization of PES membranes utilizing various zwitterions in different ratios. Utilizing molecular docking, we examined the interactions of three zwitterionic ligands-carboxybetaine methacrylate (CBMA), sulfobetaine methacrylate (SBMA), and (2-(methacryloyloxy)ethyl) phosphorylcholine (MPC)-with human serum proteins. Our analysis revealed that a 1:1 ratio of phosphobetaine and sulfobetaine exhibits the lowest affinity energy towards serum proteins, denoting an optimal hemocompatibility without the limitations associated with increased zwitterion ratios. This pivotal finding offers a new pathway for developing more efficient and safer hemodialysis membranes, promising improved care for ESRD patients.

Supplementary information

The online version contains supplementary material available at 10.1186/s42252-024-00062-6.

Hallmarks for Thrombotic and Hemorrhagic Risks in Chronic Kidney Disease Patients

Chronic kidney disease (CKD) is a global health issue causing a significant health burden. CKD patients develop thrombotic and hemorrhagic complications, and cardiovascular diseases are associated with increased hospitalization and mortality in this population. The hemostatic alterations are multifactorial in these patients; therefore, the results of different studies are varying and controversial. Endothelial and platelet dysfunction, coagulation abnormalities, comorbidities, and hemoincompatibility of the dialysis membranes are major contributors of hypo- and hypercoagulability in CKD patients. Due to the tendency of CKD patients to exhibit a prothrombotic state and bleeding risk, they require personalized clinical assessment to understand the impact of antithrombotic therapy. The evidence of efficacy and safety of antiplatelet and anticoagulant treatments is limited for end-stage renal disease patients due to their exclusion from major randomized clinical trials. Moreover, designing hemocompatible dialyzer membranes could be a suitable approach to reduce platelet activation, coagulopathy, and thrombus formation. This review discusses the molecular mechanisms underlying thrombotic and hemorrhagic risk in patients with CKD, leading to cardiovascular complications in these patients, as well as the evidence and guidance for promising approaches to optimal therapeutic management.

Biophysical studies of modified PVC sheet based on sunflower oil for antistatic and blood bags applications

In this work, the surface of polyvinyl chloride PVC sheet was modified by blending it with sunflower seed oil SSO to obtain PVC sheet/SSO films of ratios 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 (v/v)% using the solution casting method. Various techniques were used to characterize the prepared films, besides the use of hemolysis assays and blood clot formation tests. FTIR spectra revealed that there was a good interaction between the PVC sheet and the oil. The dielectric measurement indicated that SSO addition enhanced the dielectric properties of the sheet. The study of dielectric relaxation times confirmed the interaction between SSO and the sheet. DC conductivity increased to 6 × 10-6 S/m, so it could be applied in antistatic applications. Also, SSO addition increased the value of the thermal stability. According to SEM micrographs, the film was roughened at a ratio of 60/40 and smoothed out at 50/50. This behavior was confirmed with roughness and contact angle measurement results, in which the film of ratio 60/40 had the highest value equal to (72.03°) and then decreased at 50/50 to (59.62°). These results were confirmed by XRD measurement as the crystallinity increased at the film ratio of 60/40 and decreased again at 50/50. Also, the ratio of 60/40 demonstrated a large decrease in thrombus weights along with a slight increase in hemolysis, which is within the acceptable range and has a high degree of biocompatibility, so this concentration is recommended to be used in blood bags applications.

Low pulse pressure and high serum complement C1q are risk factors for hemodialysis headache: A case-control study

BACKGROUND AND OBJECTIVE

Hemodialysis headache (HDH) is a common complication of dialysis that negatively affects the patient's quality of life. The etiology and triggering factors of HDH are not fully understood. This study aims to assess the prevalence and characteristics of HDH among patients undergoing hemodialysis across multiple centers in China. Furthermore, we conducted a case-control study at one hospital to identify risk factors associated with HDH.

METHODS

The study consisted of two phases including a cross-sectional observational study and a case-control study. Participants underwent neurological examinations and interviews. Demographic and medical information were collected from both medical records and patient files. Serum creatinine, uric acid, urea, estimated glomerular filtration rate (eGFR), plasma osmolarity, glucose, C1q, and a variety of electrolytes including potassium, sodium, chloride, calcium, magnesium, and phosphorus were measured before and after dialysis. Blood pressure variables including systolic blood pressure, diastolic blood pressure, pulse pressure (PP), and heart rate were monitored hourly. Serum levels of inflammatory factors, including tumor necrosis factor α (TNF-α), interleukin (IL)-1β, IL-4, IL-6, and IL-10 were quantified using a double-antibody sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

The prevalence of HDH was 37.7% (183/485). HDH was characterized by a bilateral tightening headache of moderate intensity and duration of <2 h, occurring in different locations. The case-control study included 50 patients with HDH and 84 control patients, pre-dialysis PP was found to be lower in the HDH group than in the control group (mean ± standard deviation 51.5 ± 18.2 vs. 67.9 ± 14.9, p = 0.027). Furthermore, the pre-dialysis serum complement C1q level was significantly higher for the HDH group than the control group (median and interquartile range 201.5 [179.0-231.5] vs. 189.0 [168.9-209.0], p = 0.021). Pre-dialysis PP was associated with 5.1% decreased odds of HDH (odds ratio [OR] = 0.96; 95% confidence interval [CI], 0.93-0.99, p = 0.026), body weight was associated with a 5.4% decreased risk of HDH (OR = 0.95; 95% CI, 0.91-0.99, p = 0.013), and pre-dialysis C1q levels increased the odds of HDH by 1.9% (OR = 1.02; 95% CI, 1.01-1.03, p = 0.005).

CONCLUSION

Low PP, low body weight, and high blood complement C1q may be potential risk factors associated with HDH.

Alleviation of Oxidative Stress during Hemodialysis Sessions by Hemodialysis Membrane Innovation: A Multidisciplinary Perspective

Oxidative stress is prevalent in end-stage kidney disease patients receiving chronic hemodialysis and is associated with heavy cardiovascular disease burdens and increased mortality risks. Hemoincompatible hemodialysis membranes per se contribute to the activation of oxidative reactions and the generation of oxygen free radicals. Since the early 1990s, vitamin E-coated membranes have been extensively used in hemodialysis patients to reduce oxidative stress during hemodialysis sessions. However, the beneficial effects of vitamin E-coated membranes versus unmodified synthetic membranes on long-term patient-centered outcomes, such as survival, quality of life, and prevalence of cardiovascular diseases, remain controversial. Accordingly, novel antioxidant hemodialysis membranes were prepared to replace the use of vitamin E-coated membranes despite the translational research on these membranes unfortunately coming to a standstill. In this review, we first summarize the state-of-the-art on the use of vitamin E-coated membranes in hemodialysis patients to highlight their strengths and limitations. Then, we discuss the latest advances in fabricating antioxidant hemodialysis membranes and provide perspectives to bridge knowledge gaps between laboratorial investigations and clinical practice in fabricating antioxidant hemodialysis membranes.

Electrostatic Repulsive Features of Free-Standing Titanium Dioxide Nanotube-Based Membranes in Biofiltration Applications

This study presents the electrostatic repulsive features of electrochemically fabricated titanium dioxide nanotube (NT)-based membranes with different surface nanomorphologies in cross-flow biofiltration applications while maintaining a creatinine clearance above 90%. Although membranes exhibit antifouling behavior, their blood protein rejection can still be improved. Due to the electrostatically negative charge of the hexafluorotitanate moiety, the fabricated biocompatible, superhydrophilic, free-standing, and amorphous ceramic nanomembranes showed that about 20% of negatively charged 66 kDa blood albumin was rejected by the membrane with ∼100 nm pores. As the nanomorphology of the membrane was shifted from NTs to nanowires by varying fabrication parameters, pure water flux and bovine serum albumin (BSA) rejection performance were reduced, and the membrane did not lose its antifouling behavior. Herein, nanomembranes with different surface nanomorphologies were fabricated by a multi-step anodic oxidation process and characterized by scanning electron microscopy, atomic force microscopy, water contact angle analysis, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The membrane performance of samples was measured in 3D printed polyethylene terephthalate glycol flow cells replicating implantable artificial kidney models to determine their blood toxin removal and protein loss features. In collected urine mimicking samples, creatinine clearances and BSA rejections were measured by the spectrophotometric Jaffe method and high-performance liquid chromatography.

The Influence of Magnetic Fields on the Electrical Conductivity of Membranes based on Cotton Fabric, Honey, and Microparticles of Carbonyl Iron and Silver

In the present work, we report that the manufacturing of new environmentally friendly and low-cost materials with electrical conductivity can be roughly and finely tuned by an external magnetic field for technical and biomedical applications. With this aim in mind, we prepared three types of membranes based on cotton fabric impregnated with bee honey, carbonyl iron microparticles (CI), and silver microparticles (SmP). In order to study the influence of the metal particles and the magnetic field on the electrical conductivity of membranes, electrical devices were made. Using the "volt-amperometric" method, it was found that the electrical conductivity of the membranes is influenced by the mass ratio (mCI: mSmP) and by the B values of the magnetic flux density. It was observed that in the absence of an external magnetic field, adding microparticles of carbonyl iron mixed with silver microparticles in mass ratios (mCI: mSmP) of 1:0, 1:0.5, and 1:1 causes the electrical conductivity of the membranes based on cotton fabrics impregnated with honey to increase 2.05, 4.62, and 7.52 times, respectively, compared with that of the membrane based on cotton fabrics impregnated with honey alone. When applying a magnetic field, the electrical conductivity of the membranes with microparticles of carbonyl iron and silver increases with increasing magnetic flux density B. We conclude that the membranes are very good candidates for the fabrication of devices to be used in biomedical applications due to the possibility of remote, magnetically induced release of the bioactive compounds from honey and silver microparticles into the area of interest during medical treatment.

Preparation of polyvinyl chloride (PVC) membrane blended with acrylamide grafted bentonite for oily water treatment

The current work aims to advance the hydrophilicity, morphology, and antifouling characteristics of polyvinyl chloride (PVC) membranes for oily wastewater separation by incorporating modified bentonite. The surface of bentonite nanoparticles is altered by adopting the "grafting from" method using the surface-initiated atom transfer radical polymerization (SI-ATRP) approach. The PVC-based membrane is first prepared by blending acrylamide grafted bentonite (AAm-g-bentonite). AAm is grafted on bentonite in the presence of 2,2'-Bipyridyl and copper (I) bromide as a catalyst. The modified bentonite nanoparticles are studied using multiple techniques, such as fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), sedimentation tests, field emission scanning electron microscope (FE-SEM), etc. Flat-sheet PVC-based membrane is prepared by blending AAm-g-bentonite using the nonsolvent induced phase separation (NIPS) technique. Different methods, including FE-SEM, FTIR, sedimentation test, contact angle, porosity, antifouling property, and filtration studies of pure and oily water, are used to characterize and determine the performance of mixed-matrix membranes. Membrane performance is improved in the presence of modified bentonite (i.e., AAm-g-bentonite), with the best result achieved at PVC/AAm-g-ben-8 (i.e., 8 wt % of AAm-g-bentonite). Enhanced pure water flux (293.14 Lm^-2h^-1), permeate flux (123.96 Lm^-2h^-1), and oil rejection >93.2% are obtained by the reduced contact angle (49.1°) and improved porosity (71.22%).

A high-protein retained PES hemodialysis membrane with tannic acid as a multifunctional modifier

A high protein retention polyethersulfone (PES) membrane was prepared by nonsolvent-induced phase separation and surface coating, which exhibited enhanced hemocompatibility and antioxidant stress performance. The cross-linked network was constructed by tannic acid (TA) and alpha-lipoic acid (α-LA) on the surface of the membrane, which controlled the pores to a reasonable size. The enrichment of heparin-like groups on the membrane surface, implemented by "hydrophobic interaction" and "click reaction", confers anticoagulant properties; the presence of a large number of phenolic hydroxyl groups from TA and the introduction of α-LA allows the modified membranes to intervene in oxidative stress. The hemocompatibility characterizations included plasma recalcification time (PRT), activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT) and hemolysis rate (HR). Additionally, the DPPH ABTS radical scavenging capacity was tested to evaluate the antioxidant performance. The results show that the modified membrane presents an outstanding protein retention rate (99.3%) along with permeability. In addition, the PRT is prolonged to 341.7 s, and the DPPH• scavenging ability reaches 0.74 µmol•cm-2. The membranes can be easily prepared and present excellent comprehensive performance. This work provides a simple and facile strategy for the fabrication of hemodialysis membranes with controllable pore sizes.