A novel kind of polysulfone material with excellent biocompatibility modified by the sulfonated hydroxypropyl chitosan

Synthesis of N-isonicotinic sulfonate chitosan and its antibiofilm activity against E. coli and S.aureus

N-(sodium 2-hydroxypropylsulfonate) chitosan (HSCS), N-sulfonate chitosan (SCS) and N-isonicotinic sulfonate chitosan (ISCS) were prepared. The structures of the prepared chitosan derivatives were characterized by nuclear magnetic resonance (1H NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and elemental analysis (EA). Antibacterial and antibiofilm activities of these chitosan derivatives were evaluated in vitro. The minimum inhibitory concentration (MIC) of HSCS and SCS against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were 0.625 mg/mL and 0.156 mg/mL, respectively. ISCS exhibited MIC values of 0.313 mg/mL and 0.078 mg/mL against E. coli and S. aureus, respectively. ISCS demonstrated superior antibacterial and antibiofilm properties compared to SCS and HSCS. These findings suggest that the incorporation of a pyridine structure into sulfonate chitosan enhances its antibacterial and antibiofilm activities, and the prepared ISCS has a promising application prospect for controlling the reproduction of microorganisms in the field of food packaging.

Improving Hemocompatibility of Polysulfone Membrane by UV-Assisted Grafting of Sulfonated Chitosan

The most prevalent type of hemodialysis membrane is polysulfone (PSf). However, due to inadequate biocompatibility, it significantly compromises the safety of dialysis for patients. In this study, we modify the surface of the PSf membrane with 2,4-dihydroxybenzophenone (DBPh) groups to serve as anchoring sites during UV irradiation. Subsequently, a tailored sulfonated dihydroxy propyl chitosan (SDHPCS) is grafted onto the modified PSf membrane to compensate for the deficiencies in hydrophilic additives. The modified PSf membrane exhibits outstanding hydrophilicity and stability, as demonstrated by its characterization and evaluation. This paper focuses on investigating the interaction between platelet membrane formation, protein adsorption, and anticoagulant activity. The results show that the modified PSf membrane exhibits remarkable enhancement in surface hydrophilicity, leading to a significant reduction in protein and platelet adsorption as well as adhesion.

Surface Treatment of Polymer Membranes for Effective Biofouling Control

Membrane biofouling is the consequence of the deposition of microorganisms on polymer membrane surfaces. Polymeric membranes have garnered more attention for filtering and purifying water because of their ease of handling, low cost, effortless surface modification, and mechanical, chemical, and thermal properties. The sizes of the pores in the membranes enable micro- and nanofiltration, ultrafiltration, and reverse osmosis. Commonly used polymers for water filter membranes are polyvinyl chloride (PVA), polyvinylidene fluoride (PVDF), polyamide (PA), polyethylene glycol (PEG), polyethersulfone (PES), polyimide (PI), polyacrylonitrile (PAN), polyvinyl alcohol (PA), poly (methacrylic acid) (PMAA), polyaniline nanoparticles (PANI), poly (arylene ether ketone) (PAEK), polyvinylidene fluoride polysulfone (PSF), poly (ether imide) (PEI), etc. However, these polymer membranes are often susceptible to biofouling because of inorganic, organic, and microbial fouling, which deteriorates the membranes and minimizes their lives, and increases operating costs. Biofouling infection on polymer membranes is responsible for many chronic diseases in humans. This contamination cannot be eliminated by periodic pre- or post-treatment processes using biocides and other chemicals. For this reason, it is imperative to modify polymer membranes by surface treatments to enhance their efficiency and longevity. The main objective of this manuscript is to discuss application-oriented approaches to control biofouling on polymer membranes using various surface treatment methods, including nanomaterials and fouling characterizations utilizing advanced microscopy and spectroscopy techniques.

Effect of Molecular Weight and Chemical Structure of Terminal Groups on the Properties of Porous Hollow Fiber Polysulfone Membranes

For the first time, polysulfones (PSFs) were synthesized with chlorine and hydroxyl terminal groups and studied for the task of producing porous hollow fiber membranes. The synthesis was carried out in dimethylacetamide (DMAc) at various excesses of 2,2-bis(4-hydroxyphenyl)propane (Bisphenol A) and 4,4'-dichlorodiphenylsulfone, as well as at an equimolar ratio of monomers in various aprotic solvents. The synthesized polymers were studied by nuclear magnetic resonance (NMR), differential scanning calorimetry, gel permeation chromatography (GPC), and the coagulation values of 2 wt.% PSF polymer solutions in N-methyl-2-pyrollidone were determined. According to GPC data, PSFs were obtained in a wide range of molecular weights M_w from 22 to 128 kg/mol. NMR analysis confirmed the presence of terminal groups of a certain type in accordance with the use of the corresponding monomer excess in the synthesis process. Based on the obtained results on the dynamic viscosity of dope solutions, promising samples of the synthesized PSF were selected to produce porous hollow fiber membranes. The selected polymers had predominantly -OH terminal groups and their molecular weight was in the range of 55-79 kg/mol. It was found that porous hollow fiber membrane from PSF with M_w 65 kg/mol (synthesized in DMAc with an excess of Bisphenol A 1%) has a high helium permeability of 45 m³/m²∙h∙bar and selectivity α (He/N₂) = 2.3. This membrane is a good candidate to be used as a porous support for thin-film composite hollow fiber membrane fabrication.

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.

Graphical Abstract

Recent advancement challenges with synthesis of biocompatible hemodialysis membranes

The focus of this study is to enhance the protein fouling resistance, hydrophilicity, biocompatibility, hemocompatibility and ability of the membranes and to reduce health complications like chronic pulmonary disease, peripheral vascular disease, cerebrovascular disease, and cardiovascular disease after dialysis, which are the great challenges in HD applications. In the current study, the PSF-based dialysis membranes are studied broadly. Significant consideration has also been provided to membrane characteristics (e.g., flowrate coefficient, solute clearance characteristic) and also on commercially available polysulfone HD membranes. PSF has gained a significant share in the development of HD membranes, and continuous improvements are being made in the process to make high flux PSF-based dialysis membranes with enhanced biocompatibility and improved protein resistance ability as the major issue in the development of membranes for HD application is biocompatibility. There has been a great increase in the demand for novel biocompatible membranes that offer the best performances during HD therapy, for example, low oxidative stress and low change ability of blood pressure.

Preparation and blood compatibility of polyethersulfone dialysis membrane modified by apixaban as coagulation factor Xa inhibitor

Blood purification therapy is widely used in the treatment of critically ill patients. However, most dialysis membranes are prone to thrombosis. Activated coagulation factor X (FXa) functions at the intersection of intrinsic, extrinsic, and common coagulation pathways and plays a central role in thrombogenesis. To date, few dialysis membranes that directly inhibit FXa have been reported. We modified a polyethersulfone(PES) membrane using apixaban as an FXa inhibitor and investigated the performance of this membrane (AMPES). The contact angle of the modified membrane was reduced. PWF and retention rates of BSA were increased, demonstrating good hydrophilicity and dialysis performance. Albumin adsorption was reduced from 141.8 ± 15.5 to 114.1 ± 6.9 μg cm^-2. Reduced protein adsorption, especially targeted anti-FXa effect, inhibited the activation of intrinsic, extrinsic, and common coagulation pathways, as evidenced by significant prolongations of activated partial thromboplastin time, prothrombin time, and thrombin time by 145.04, 46.84 and 11.46 s, respectively. Furthermore, we determined the FXa concentration of each group, and found that the modified membrane had better anticoagulant performance through the inhibition of FXa. Favorable antiplatelet activity was also demonstrated. Thromboelastogram was used to comprehensively evaluate the anticoagulant and antithrombotic activities of the modified membrane. The R value was increased by 43.1 min, while the reduction in α angle was 42.5°. The coagulation comprehensive index reduction was 34.3. In addition, C3a and C5a were decreased by 15.3 % and 30.4 %, respectively. Furthermore, in vitro cytotoxicity and erythrocyte stability testing as well as in vivo murine experiments demonstrated the biosafety of the modified membrane. These results indicate that the AMPES dialysis membrane has an excellent potential for clinical applications.

Hydrophilicity and flux properties improvement of high performance polysulfone membranes via sulfonation and blending with Poly(lactic acid)

To achieve increased flow and reduce fouling, polymeric membranes can be functionalized with hydrophilic groups such as sulfone, amines, and others. This research has aimed at the sulfonation of Polysulfone (PSU) with various agents and at varying substitution degrees to change its hydrophobic character. PSU was also blended with Poly(lactic acid) (PLA), which is a more hydrophilic polymer. The phase inversion method was used to make PSU, PLA, sulfonated PSU, and PSU/PLA blend-based membranes. Sulfonation degrees of sulfonated PSU membranes were assessed using FT-IR, mechanical characteristics of membranes were determined, and thermal properties of membranes were clarified using DSC and TGA techniques. Hydrophilic natures and membrane alterations were investigated, as well as contact angle and water uptake measures. Among three distinct sulfonation agents (trimethylsilyl chlorosulfonate (TMSCS), sulfuric acid, and chlorosulfonic acid) employed to produce a 20% sulfonation degree of polysulfone, TMSCS was chosen as having the highest sulfonation efficiency (91.5%). With increasing sulfonation degree, a drop in molecular weight was seen in all sulfonated polysulfone samples. The mechanical strength values of polysulfone after sulfonation with TMSCS rose from 35.23 MPa to 63.35 MPa, while the contact angle value decreased from 85.58° to 71°. The contact angle value reduced from 85.58° to 64.68° while the mechanical strength of the PSU and PSU/PLA (50:50) blend increased from 35.23 MPa to 39.3 MPa. Membranes were also tested for pure water flux, hydrostability, and biostability. In terms of application requirements, it was determined that sulfonated PSU-based membranes manufactured with TMSCS with a 20% sulfonation degree and PSU/PLA blend-based membranes with a 50:50 (w:w) ratio have the optimum compositions with high flux quantities.

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.

Enhanced hydrophilicity and anticoagulation of polysulfone materials modified via dihydroxypropyl, sulfonic groups and chitosan

A novel modified polysulfone (PSF) is successfully prepared for hemodialysis by grafting with a well-defined heparin-like polymer, sulfonated dihydroxypropyl chitosan (SDHPCS), which is obtained in proper sequence via alkalization of chitosan, etherification and sulfonation. PSF is modified via chloroacetyl chloride, and then, the chloroacylated polysulfone (CAPSF) with pristine PSF is transformed into CAPSF/PSF blend membrane via the phase inversion, followed introducing amino group into CAPSF on the surface and taking glutaraldehyde as bridge between modified PSF membrane and SDHPCS. The result of ¹H NMR spectrum of prepared CAPSF indicates that the degree of the substitution of chloroacetyl group. The SEM, EDS mapping, FTIR and XPS show that SDHPCS-g-PSF membranes are successfully prepared. The hydrophilicity of the membrane modified by SDHPCS is improved obviously, and the contact angle remarkably reduced from 87 ° to below 45°, exhibiting much better hydrophilicity. The hemocompatibility characterizations including BSA adsorption, Plasma recalcification time (PRT), hemolysis ratio (HR), activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT) also certificates that SDHPCS-g-PSF possesses lower BSA adsorption and enhanced blood compatibility.

Dialdehyde pectin-crosslinked and hirudin-loaded decellularized porcine pericardium with improved matrix stability, enhanced anti-calcification and anticoagulant for bioprosthetic heart valves

To conveniently and effectively cure heart valve diseases or defects, combined with transcatheter valve technology, bioprosthetic heart valves (BHVs) originated from the decellularized porcine pericardium (D-PP) have been broadly used in clinics. Unfortunately, most clinically available BHVs crosslinked with glutaraldehyde (GA) were challenged in their long-term tolerance, degenerative structural changes, and even failure, owing to the synergistic impact of multitudinous elements (cytotoxicity, calcification, immune responses, etc.). In this work, dialdehyde pectin (AP) was prepared by oxidizing the o-dihydroxy of pectin with sodium periodate. Hereafter, the AP-fixed PP model was obtained by crosslinking D-PP with AP with high aldehyde content (6.85 mmol g^-1), for acquiring excellent mechanical properties and outstanding biocompatibility. To further improve the hemocompatibility of the AP-fixed PP, a natural and specific inhibitor of thrombin (hirudin) was introduced to achieve surface modification of the AP-fixed PP. The feasibility of crosslinking and functionalizing AP-fixed PP, which was a potential leaflet material of BHVs, was exhaustively and systematically evaluated. In vitro studies found that hirudin-loaded and AP-fixed PP (AP + Hirudin-PP) had synchronously achieved effective fixation of collagen, highly effective anticoagulation, and good HUVECs-cytocompatibility. In vivo results revealed that the AP + Hirudin-PP specimens recruited the minimum immune cells in the implantation experiment, and also presented an excellent anti-calcification effect. Overall, AP + Hirudin-PP was endowed with competitive collagen stability (compared with GA-fixed PP), excellent hemocompatibility, good HUVECs-cytocompatibility, low immunogenicity and outstanding anti-calcification, suggesting that AP + Hirudin-PP might be a promising alternative to GA-fixed PP and exhibited a bright prospect in the clinical applications of BHVs.

Nano architectured cues as sustainable membranes for ultrafiltration in blood hemodialysis

Membranes with zeolites are encouraging for performing blood dialysis because zeolites can eliminate uremic toxins through molecular sieving. Although the addition of various pore-gen and adsorbent in the membrane can certainly impact the membrane production along with creatinine adsorption, however, it is not directed which pore-gen along with zeolite leads to better performance. The research was aimed at reducing the adsorption of protein-bound and uremic toxins by using mordenite zeolite as an adsorbent while polyethylene glycol and cellulose acetate as a pore generating agent. Membranes were cast by a phase-inversion technique which is cheap and easy to handle as compared to the electro-spinning technique. Through this strategy, the ability to adsorb creatinine and solute rejection percentage were measured and compared against the pristine PSU, when only PEG was used as a pore-modifier and when PEG along with CA was used as a pore-modifier along with a different concentration of zeolite. The experiments revealed that PEG membranes can give a better solute rejection percentage (93%) but with a low creatinine adsorption capacity that is 7654 μg/g and low bio-compatibility (PRT 392 s, HR 0.46%). However, PEG/CA membranes give maximum creatinine adsorption that is 9643 μg/g and also better bio-compatibility (PRT 490 s, HR 0.37%) but with a low BSA rejection (72%) as compared to the pristine PSU and PEG membranes. The present study finds that the concentration of mordenite zeolite affects the membrane performance because its entrapment and large pore size of the membrane decreases solute rejection but increases creatinine uptake level along with the better bio-compatibility.

Preparation of modified polysulfone material decorated by sulfonated citric chitosan for haemodialysis and its haemocompatibility

Polysulfone (PSF) works potentially in haemodialysis due to its great mechanical and chemical stability, but performs poorly in haemocompatibility. For promoting the unpleasant haemocompatibility, sulfonated citric chitosan (SCACS) with the structure and groups similar to heparin was primarily synthesized by acylation and sulfonation. Furthermore, the chloroacylated PSF was pretreated by electrophilic chloroacetyl chloride to achieve more active sites for further reaction; the following membranes underwent the amination and were named amination polysulfone (AMPSF) membranes. Moreover, SCACS with abundant carboxyl and sulfonic groups was covalently grafted at the surface of pretreated PSF membranes, called PSF-SCACS membranes. The PSF-SCACS membranes were successfully synthesized and characterized by 1H NMR, ATR-FTIR and XPS. In addition, the water contact angle of PSF-SCACS membranes decreased by 47° and the morphologies of the membranes changed little compared with the unmodified PSF membranes. The haemocompatible testing results, including protein adsorption, platelet adhesion, haemolysis rate, plasma recalcification time, activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT), demonstrated that the PSF-SCACS membranes possessed excellent haemocompatible performances, and SCACS played an important role in the modification.

Hydroxypropyl chitosan/soy isolate protein conduits promote peripheral nerve regeneration

Designing scaffolds, with optimized micro-structure and function for promoting the release of neuro-related factors, is significant in peripheral nerve regeneration. Herein, a series of hydroxypropyl chitosan/soy protein isolate composite sponges (HCSS) were fabricated by a freeze-drying technique. The physicochemical properties of the resultant HCSS were examined by a Fourier infrared spectrometer, X-ray diffractometer, scanning electron microscope, water absorption assay, water retention assay, and compressive strength assay. The results indicated that HCSS exhibited an interconnected porous micro-structure and a high water retention ratio with the increase in SPI content. The biological characterization found that the HCSS-50 containing 50% SPI content profoundly promoted the proliferation of RSC96 cells and the secretion of neuro-related factors without excessive ROS production. In addition, HCSS-50 could significantly promote the expression of neuro-related factors; for example, the expression of TGF-β was 3 times higher than that of the control group. Finally, an optimized HCSS-based conduit was fabricated from HCSS-50 to repair sciatic nerve injury in rats with the combination of BMSCs or BMSC-derived Schwann cells. The results suggested that the constructed HCSS-based conduit accompanying BMSC-derived Schwann cells could effectively promote axonal regeneration and upregulate expression of neuro-related factors such as Krox20, Zeb2, and GAP43. Collectively, a newly engineered nerve conduit system was developed by incorporating HCSS-50 and BMSC-derived Schwann cells, which could be an alternative candidate for peripheral nerve regeneration.

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.

Vorapaxar-modified polysulfone membrane with high hemocompatibility inhibits thrombosis

Hemodialysis therapy is intended for patients suffering from renal insufficiency, pancreatitis, and other serious diseases. Platelets are an important active ingredient in the thrombosis induced by hemodialysis membranes. So far, there are few studies of hemodialysis membranes focusing on the effects of protease-activated receptor 1 (PAR1) activation on the platelet membrane. Among various antithrombotic agents, vorapaxar is a novel PAR1 inhibitor with high efficacy. In this study, we constructed a vorapaxar-modified polysulfone (VMPSf) membrane using immersion-precipitation phase transformation methods and characterized the microstructure in terms of hydrophilicity and mechanical properties. The water contact angle of the VMPSf membrane was 22.45% lower than that of the PSf membrane. A focused determination of platelet morphology was obtained using scanning electron microscopy. Meanwhile, we evaluated the effects of a VMPSf membrane on platelet adhesion. We observed that the VMPSf membrane could reduce the number of adhered platelets without altering their spherical or elliptical shape. The PAR1 levels in VMPSf membranes were 7.4 MFI lower than those in PSf membranes, suggesting that this modified membrane can effectively inhibit platelet activation. Activated partial thromboplastin time (APTT, 5.3 s extension) and thrombin time (TT, 2.1 s extension) reflect good anticoagulant properties. Recalcification time (80.6 s extension) and fibrinogen adsorption (9.9 μg/cm² reduction) were related to antithrombotic properties. To determine the biosafety of VMPSf membranes, we investigated antianaphylactic and anti-inflammatory properties in vitro and acute toxicity in vivo, it was obvious that C3a and C5a had decreased to 9.6 and 0.8 ng/mL, respectively. The results indicated that the VMPSf membrane has potential for clinical application.

A novel anticoagulant affinity membrane for enhanced hemocompatibility and bilirubin removal

Affinity membrane is widely employed to promote specific adsorption of toxins and reduce the blood purification therapeutic time. However, it suffers from insufficient toxin binding and low hemocompatibility. Herein, a novel anticoagulant affinity membrane (AAM) was developed to clear bilirubin from human blood in a pore-flow-through way. Firstly, a nylon net membrane with a regularly arranged pore as the matrix was coated with poly(pyrrole-3-carboxylic acid) via chemical vapor deposition (CVD) method. Then, poly(L-arginine) (PLA) as a highly specific ligand of bilirubin, was immobilized onto the surface of the composited membrane after the modification of heparin. Owing to the 3-dimensional molecular architecture of PLA, up to 86.1 % of bilirubin was efficiently cleared. Besides, the AAM exhibited effective anticoagulant activity in the measurement of clotting time, with suppressed thrombus formation, low hemolysis ratio, minimized platelet and leukocyte adhesion, and excellent biosafety. Therefore, the AAM has enormous potential in blood purification therapy for enhancing hemocompatibility and bilirubin removal.

In-Vitro Study of Polysulfone-polyethylene glycol/chitosan (PEG-PSf/CS) Membranes for Urea and Creatinine Permeation

High concentrations of creatinine and urea in the blood can be removed by dialysis using semipermeable membranes that are selective for certain species and hold other species through diffusion processes. This ability requires a membrane that has an active side, which functions as a targeted species identifier. The membrane must be biocompatible because the membrane will be in direct contact with the body’s biological systems. The membrane material that is made must be acceptable to the blood system so that there is no rejection from the body and have a large contact area to obtain an effective diffusion process. For this reason, a hollow fiber membrane (HFM) is needed. One of the synthetic polymers used as the base material for HFM is PSf. PSf has mechanical strength, heat resistance, and is easily formed into HFM. However, PSf has disadvantages such as lack of active side and less compatible with blood due to its hydrophobic properties. Modification using PEG and chitosan will reduce the hydrophobicity of the PSf. Membrane results were analyzed the physical, chemical, and transportability for urea and creatinine. The results of functional group characterization by FTIR show that the modification reaction was successfully carried out on polysulfone to produce PEG-PSf/CS. The modification succeeded in making the PSf membrane more hydrophilic, as evidenced by a decrease in the contact angle from 69.4° (PSf) to 53° (PEG-PSf/CS). Water uptake capability increases to 609%, and membrane porosity increases porosity increased from 72 to 83%. The water flux is also increased. Creatinine clearance ability increases from 0.09 mg/dl to 0.25 mg/dL. Urea clearance ability increases from 2.3 mg/dL to 3.07 mg/dL. The SEM image showed that the modification makes the membranes more porous.

The hemocompatibility of the modified polysulfone membrane with 4-(chloromethyl)benzoic acid and sulfonated hydroxypropyl chitosan

Polysulfone (PSf) membrane is widely employed in blood purification fields, but the blood compatibility of PSf membrane is not adequate. To improve the hemocompatibility of PSf membrane, 4-(chloromethyl)benzoic acid (CMBA) and sulfonated hydroxypropyl chitosan (SHPCS) were grafted onto PSf membrane surface. In our strategy, CMBA was firstly grafted on the PSf membrane surface through the Friedel-Crafts alkylation reaction, and the product was named BAPSf membrane. Then, SHPCS was grafted onto the BAPSf membrane surface by esterification, and the product was named SHPCS-BAPSf membrane. The effects of temperature and reaction time on the productivity of BAPSf and the grafting density of carboxyl and the effects of reaction time on the grafting density of SHPCS grafted onto the BAPSf membrane surface were studied. The SHPCS-BAPSf membranes are investigated by ATR-FTIR, XPS, contact angle measurements and evaluated by blood compatibility in vitro. The results reveal that the hydrophilicity of SHPCS-BAPSf membranes were grealy improved and the evaluation of protein adsorption, hemolysis test, platelet adhesion plasma recalcification time(PRT), activated partial thromboplastin time(APTT), prothrombin time(PT) and thrombin time(TT) confirmed that the SHPCS-BAPSf membranes have remarkable blood compatibility.

A review on applications of chitosan-based Schiff bases

Biopolymers have become very attractive as they are degradable, biocompatible, non-toxic and renewable. Due to the intrinsic reactive amino groups, chitosan is vibrant in the midst of other biopolymers. Using the versatility of these amino groups, various structural modifications have been accomplished on chitosan through certain chemical reactions. Chemical modification of chitosan via imine functionalization (RR'CNR″; R: alkyl/aryl, R': H/alkyl/aryl and R″: chitosan ring) is significant as it recommends the resultant chitosan-based Schiff bases (CSBs) for the important applications in the fields like biology, catalysis, sensors, water treatment, etc. CSBs are usually synthesized by the Schiff condensation reaction between chitosan's amino groups and carbonyl compounds with the removal of water molecules. In this review, we first introduce the available synthetic approaches for the preparation of CSBs. Then, we discuss the biological applications of CSBs including antimicrobial activity, anticancer activity, drug carrier ability, antioxidant activity and tissue engineering capacity. Successively, the applications of CSBs in other fields such as catalysis, adsorption and sensors are demonstrated.

Surface hemocompatible modification of polysulfone membrane via covalently grafting acrylic acid and sulfonated hydroxypropyl chitosan

In this study, acrylic acid (AA) and sulfonated hydroxypropyl chitosan (SHPCS) were covalently grafted on the PSf membrane surface to improve its hemocompatibility.