Ionic-strength-sensitive polyethersulfone membrane with improved anti-fouling property modified by zwitterionic polymer via in situ cross-linked polymerization

Zwitterionic nanospheres engineered co-polymer composite membrane for precise protein-protein separation via dynamic self-assembly micelle deposition

The accurate protein-protein separation is important but technically challenging. Achieving such a precise separation using membrane requires the selective channels with appropriate pore geometry structure and high anti-fouling property. In this study, polyethersulfone-b-poly(sulfobetaine methyl methacrylate) (PES-b-PSBMA) was synthesized and engineered onto polysulfone (PSF) ultrafiltration (UF) membrane to fabricate zwitterionic nanospheres engineered co-polymer (ZN-e-CoP) composite membrane via dynamic self-assembly micelle deposition. On the one hand, self-assembly zwitterionic nanospheres were used as blocks to construct hydrophilic layers with size-dependent sieving channels, endowing ZN-e-CoP composite membranes with enhanced permselectivity and protein-protein separation abilities, meanwhile zwitterionic groups from nanospheres reinforced the structure stability of nanospheres/nanospheres and nanospheres/membrane via multiple intermolecular interactions. On the other hand, zwitterionic nanospheres can induce to produce the hydration layer enveloping themselves by binding water molecules, where hydration layer acts as a protective barrier on the membrane surface, impeding the protein adhesion. Hence, ZN-e-CoP_1a composite membrane exhibited superior separation properties with Lysozyme/Bovine Serum Albumin (BSA) separation factor of 18.1 and 95.4 % rejection against BSA, 10.1 and 2.3 times, respectively, higher these of pristine PSF membrane (1.8 and 42.1 %), without obviously sacrificing water flux. Simultaneously, hydration layer enables the ZN-e-CoP_1a membrane with enhanced anti-fouling performance and durability during the long-term operations. The proposed approach opens new pathways to fabricate excellent anti-fouling membranes for precise protein-protein separation.

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.

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.

Impact of Membrane Modification and Surface Immobilization Techniques on the Hemocompatibility of Hemodialysis Membranes: A Critical Review

Despite significant research efforts, hemodialysis patients have poor survival rates and low quality of life. Ultrafiltration (UF) membranes are the core of hemodialysis treatment, acting as a barrier for metabolic waste removal and supplying vital nutrients. So, developing a durable and suitable membrane that may be employed for therapeutic purposes is crucial. Surface modificationis a useful solution to boostmembrane characteristics like roughness, charge neutrality, wettability, hemocompatibility, and functionality, which are important in dialysis efficiency. The modification techniques can be classified as follows: (i) physical modification techniques (thermal treatment, polishing and grinding, blending, and coating), (ii) chemical modification (chemical methods, ozone treatment, ultraviolet-induced grafting, plasma treatment, high energy radiation, and enzymatic treatment); and (iii) combination methods (physicochemical). Despite the fact that each strategy has its own set of benefits and drawbacks, all of these methods yielded noteworthy outcomes, even if quantifying the enhanced performance is difficult. A hemodialysis membrane with outstanding hydrophilicity and hemocompatibility can be achieved by employing the right surface modification and immobilization technique. Modified membranes pave the way for more advancement in hemodialysis membrane hemocompatibility. Therefore, this critical review focused on the impact of the modification method used on the hemocompatibility of dialysis membranes while covering some possible modifications and basic research beyond clinical applications.

Advancements in modification of membrane materials over membrane separation for biomedical applications-Review

A comprehensive overview of various modifications carried out on polymeric membranes for biomedical applications has been presented in this review paper. In particular, different methods of carrying out these modifications have been discussed. The uniqueness of the review lies in the sense that it discusses the surface modification techniques traversing the timeline from traditionally well-established technologies to emerging new techniques, thus giving an intuitive understanding of the evolution of surface modification techniques over time. A critical comparison of the advantages and pitfalls of commonly used traditional and emerging surface modification techniques have been discussed. The paper also highlights the tuning of specific properties of polymeric membranes that are critical for their increased applications in the biomedical industry specifically in drug delivery, along with current challenges faced and where the future potential of research in the field of surface modification of membranes.

A high-performance solid electrolyte assisted with hybrid biomaterials for lithium metal batteries

The demand for high safety lithium batteries has led to the rapid development of solid electrolytes. However, some inherent limitations of solid polymer electrolytes (SPEs) impede them achieving commercial value. In this work, a novel polyethylene oxide (PEO)-based solid electrolyte is reported. For the first time, biomaterial-based chitosan-silica (CS) hybrid particles serve as fillers, which can interact with polymer matrix to significantly improve the electrochemical performance. The optimized polymer electrolyte exhibits a maximum ion conductivity of 1.91 × 10^-4 S·cm^-1 at 30 °C when the mass ratio of PEO and CS is 4:1 (PCS4). All-solid-state LiFePO₄|PCS4|Li cells deliver a high coulombic efficiency and stable cycling performance, remaining an excellent capacity of more than 96.2 % after 150 cycles. Furthermore, the wide electrochemical window (5.4 V) and steady interfacial stability provide the possibility for high-voltage batteries applications. NCM811|| Li cells are assembled and display reliable charge and discharge cycle properties.

Dual-responsive zwitterion-modified nanopores：a mesoscopic simulation study

In this work, dissipative particle dynamics simulation was carried out to investigate the intelligent switching effect of nanopores grafted by the zwitterionic polymer brushes poly(carboxybetaine) with excellent antifouling property. The...

Fouling of polyelectrolyte multilayer based nanofiltration membranes during produced water treatment: The role of surfactant size and chemistry

Large volumes of water become contaminated with hydrocarbons, surfactants, salts and other chemical agents during Oil & Gas exploration activities, resulting in a complex wastewater stream known as produced water (PW). Nanofiltration (NF) membranes are a promising alternative for the treatment of PW to facilitate its re-use. Unfortunately, membrane fouling still represents a major obstacle. In the present work, we investigate the effect of surface chemistry on fouling of NF membranes based on polyelectrolyte multilayers (PEM), during the treatment of artificial produced water. To this end, oil-in-water (O/W) emulsions stabilized with four different surfactants (anionic, cationic, zwitterionic and non-ionic) were treated with PEM-based NF membranes having the same multilayer, but different top layer polymer chemistry: crosslinked poly(allylamine hydrochloride) (PAH, nearly uncharged), poly(sodium 4-styrene sulfonate) (PSS, strongly negative), poly(sulfobetaine methacrylate-co-acrylic acid) (PSBMA-co-AA, zwitterionic) and Nafion (negative and hydrophobic). First, we study the adsorption of the four surfactants for the four different surfaces on model interfaces. Second, we study fouling by artificial produced water stabilized by the same surfactants on PEM-based hollow fiber NF membranes characterized by the same multilayer of our model surfaces. Third, we study fouling of the same surfactants solution but without oil. Very high oil retention (>99%) was observed when filtering all the O/W emulsions, while the physicochemical interactions between the multilayer and the surfactants determined the extent of fouling as well as the surfactant retention. Unexpectedly, our results show that fouling of PEM-based NF membranes, during PW treatment, is mainly due to membrane active layer fouling caused by surfactant uptake inside of the PEM coating, rather than due to cake layer formation. Indeed, it is not the surface chemistry of the membrane that determines the extent of fouling, but the surfactant interaction with the bulk of the PEM. A denser multilayer, that would stop these molecules, would benefit PW treatment by decreasing fouling issues, as would the use of slightly more bulky surfactants that cannot penetrate the PEM.

Molecular Understanding of Ion Effect on Polyzwitterion Conformation in an Aqueous Environment

Polyzwitterions (PZs) are promising materials for the antifouling in reverse osmosis and nanofiltration membrane technology for water treatment. Fundamental understanding of the structure and molecular interactions involving zwitterions is crucial to the optimal design of antifouling in membrane separation. Here we employ the umbrella sampling and molecular dynamics simulations to investigate molecular interactions between sulfobetaine/carboxybetaine zwitterions and different metal ions (Na⁺, K⁺, and Ca²⁺) in an aqueous solution. The simulation results show that these ions can form stable or metastable contact ionic/solvent-shared-ionic pairs with zwitterions. Simulations at different grafting densities of PZ brush arrays reveal complex competitive association mechanisms, which are attributed to nonbonded electrostatic and van der Waals interactions among zwitterions, water molecules, and different metal ions in an aqueous environment. While the high-grafting density of the PZ brush array leads to a strong branch association between different zwitterions in water, this association is decreased at intermediate- and low-grafting densities due to strong zwitterion-water interactions. More importantly, adding ions into water at intermediate- and low-grafting densities further breaks down the zwitterion branch association, resulting in a randomly oriented and dispersed branch configuration with significant swelling of the polymers. The degree of swelling depends on the type of ions, which further changes the surface electrostatic potential of PZ coatings.

Bio-inspired anchoring of amino-functionalized multi-wall carbon nanotubes (N-MWCNTs) onto PES membrane using polydopamine for oily wastewater treatment

The major problem that limits the utilization of PES membranes in treatment of oily wastewater is the drastic irreversible membrane fouling due to the attachment of oil droplets onto the membrane surface. The goal of this study was to develop a novel, fast and facile post-functionalization of polydopamine (PDA) coated membranes using pre-synthesized nanoparticles for fabrication of novel organic-inorganic hybrid recoverable membranes with high hydrophilicity and underwater oleophobicity. Here, bio-inspired technique was studied because the membrane technology could separate small oil droplets (even <10 µm) with high performance if faced little fouling phenomena during the treatment process. The amino-functionalized multi-wall carbon nanotubes (N-MWCNTs) were anchored onto the PDA coated PES membranes. The membranes characteristics, with specific focus on surface morphology and wettability were investigated. The newly developed PES/PDA/N-MWCNTs membranes showed an enhanced flux (~1086%) compared to the unmodified PES membrane. This enhancement was attributed to the high hydrophilic and underwater oleophobic properties, which were found to alleviate the effect of fouling. The total fouling ratio (R_t) of the PES/PDA/N-MWCNTs membrane was 22.35%, which was far lower than that of the unmodified PES membrane (98.38%). Meanwhile, most of the fouling was reversible for the former with the remaining (irreversible fouling) of 18.08%. It was concluded that cake filtration is the dominant fouling mechanism of the PES/PDA/N-MWCNTs membranes due to their average pore diameter. The modified membranes showed high oil rejection (>99%) so that the obtained clean water with oil concentration lower than 5 ppm met the wastewater discharge standard recommendations. Also, evaluation of the PES/PDA/N-MWCNT membrane in cross-flow filtration showed its antifouling properties in the long-term application (16 h).

Ionic-Strength Responsive Zwitterionic Copolymer Hydrogels with Tunable Swelling and Adsorption Behaviors

In this work, we studied the swelling behavior and adsorption behavior of zwitterionic copolymer hydrogels, which were prepared via the free radical copolymerization of sulfobetaine methacrylate (SBMA) and other monomers including sodium p-styrenesulfonate (NaSS), acrylic acid, N-isopropylacrylamide, and 2-(dimethylamino) ethyl methacrylate. The PSBMA hydrogel showed increased swelling ratio with the increase of ionic strength at the same temperature, and the swelling process reflected endothermicity. Interestingly, the PSBMA-NaSS hydrogels collapsed when the ionic strength increased because the ions can weaken the repulsive interaction of the anionic groups of PNaSS. In addition, the PSBMA-NaSS showed high adsorption of methylene blue (760 mg/g). The zwitterionic hydrogels have potential to be used as an adsorbent in the field of wastewater treatment.

Optical stereolithography of antifouling zwitterionic hydrogels

This paper reports the rapid 3D printing of tough (toughness, U_T, up to 141.6 kJ m⁻³), highly solvated (ϕ^water ∼ 60 v/o), and antifouling hybrid hydrogels for potential uses in biomedical, smart materials, and sensor applications, using a zwitterionic photochemistry compatible with stereolithography (SLA).

Low-fouling PES membranes fabricated via in situ copolymerization mediated surface zwitterionicalization

PEGylated and zwitterionic PES membranes were fabricated during membrane formation, showing superior antifouling and anticoagulant properties.

Ionic strength- and thermo-responsive polyethersulfone composite membranes with enhanced antifouling properties

Zwitterionic polymer modified membranes were prepared, which showed ionic strength- and thermo-responsive properties.

Anion-Responsive Poly(ionic liquid)s Gating Membranes with Tunable Hydrodynamic Permeability

Novel anion-responsive "intelligent" membranes with functional gates are fabricated by filling polyethersulfone microporous membranes with poly(ionic liquid)s (PILs) gels. The wetting properties of the PILs could be controlled by changing their counteranions (CAs), and thus, the filled PILs gel gates in the membrane pores could spontaneously switch from the "closed" state to the "open" one by recognizing the hydrophilic CAs in the environment and vice versa. As a result, the fluxes of the "intelligent" membranes could be tuned from a very low level (0 mL/m²·mmHg for Cl^-, Br^-, and BF₄^-) to a relatively high one (430 mL/m²·mmHg for TFSI). The anion-responsive gating behavior of the PILs filled membranes is fast, reversible, and reproducible. In addition, the "intelligent" membranes are sensitive to contact time and ion concentrations of the hydrophobic CA species. The proposed anion-responsive "intelligent" membranes are highly attractive for ion-recognizable chemical/biomedical separations and purifications.

Design of Antibacterial Poly(ether sulfone) Membranes via Covalently Attaching Hydrogel Thin Layers Loaded with Ag Nanoparticles

To inhibit bacteria attachment and the subsequent formation of biofilms on poly(ether sulfone) (PES) membranes, poly(sulfobetaine methacrylate)/poly(sodium acrylate) antibacterial hydrogel thin layers were covalently attached onto the membranes, followed by loading with Ag nanoparticles. In our strategy, double bonds were firstly introduced onto the PES membrane surfaces to provide anchoring sites, and then the hydrogel layers were synthesized on the membrane surfaces via UV light-initiated crosslinking copolymerization. Then, Ag ions were adsorbed into the hydrogel layers and reduced to Ag nanoparticles by sodium borohydride. The amounts of the adsorbed Ag ions were controlled by the mole ratios of carboxylate groups in the hydrogel layers. After attaching the hydrogel layers, a typical 3D porous structure was observed by scanning electron microscopy, and the surface chemical composition variations were characterized by attenuated total reflection-Fourier transform infrared spectroscopy. The live/dead staining, inhibition zone, and the optical degree of co-culture solution demonstrated that the designed surfaces could not only effectively resist bacteria attachment but also kill the surrounding bacteria Escherichia coli and Staphylococcus aureus. It was noteworthy that the strong antibacterial ability could be maintained for more than 5 weeks. Additionally, the excellent hemocompatibility of the modified membranes was confirmed by undetectable plasma protein adsorption, suppressed platelet adhesion, prolonged clotting time, low hemolysis ratio, and suppressed blood-related complement activation. Cell culture tests indicated that the membranes showed no cytotoxicity, but strong anti-cell adhesion properties. The proposed method to fabricate antibacterial hydrogel thin layers has great potential to be widely used to inhibit the formation of biofilms on various biomedical devices.

Fabrication optimization of polyethersulfone (PES)/polyvinylpyrrolidone (PVP) nanofiltration membranes using Box–Behnken response surface method

Herein response surface methodology (RSM) is employed to optimize the fabrication of polyethersulfone (PES) nanofiltration (NF) membranes via phase inversion.

Direct catechol conjugation of mussel-inspired biomacromolecule coatings to polymeric membranes with antifouling properties, anticoagulant activity and cytocompatibility

TheO-sulfated chitosan andN,O-sulfated chitosan coatings were prepared by direct catechol conjugation to enrich the biological applications of polymeric membranes.

A self-defensive bilayer hydrogel coating with bacteria triggered switching from cell adhesion to antibacterial adhesion

(1) A self-defensive bacterial infection responsive bilayer hydrogel coating was designed; (2) the bilayer coating could promote cell adhesion and proliferation; and (3) the surface showed bacterial infection sensitive switching from a cell adhesion surface to an antibacterial adhesion surface by detaching the upper layer.

Hydrophilicity and anti-fouling modification of polyethersulfone membrane by grafting copolymer chains via surface initiated electrochemically mediated atom transfer radical polymerization

Polyethersulfone membrane is modified by grafting copolymer chainsviathe SI-eATRP method for improvement of hydrophlicity and anti-fouling performance.

A versatile approach towards multi-functional surfaces via covalently attaching hydrogel thin layers

In this study, a robust and straightforward method to covalently attach multi-functional hydrogel thin layers onto substrates was provided. In our strategy, double bonds were firstly introduced onto substrates to provide anchoring points for hydrogel layers, and then hydrogel thin layers were prepared via surface cross-linking copolymerization of the immobilized double bonds with functional monomers. Sulfobetaine methacrylate (SBMA), sodium allysulfonate (SAS), and methyl acryloyloxygen ethyl trimethyl ammonium chloride (METAC) were selected as functional monomers to form hydrogel layers onto polyether sulfone (PES) membrane surfaces, respectively. The thickness of the formed hydrogel layers could be controlled, and the layers showed excellent long-term stability. The PSBMA hydrogel layer exhibited superior antifouling property demonstrated by undetectable protein adsorption and excellent bacteria resistant property; after attaching PSAS hydrogel layer, the membrane showed incoagulable surface property when contacting with blood confirmed by the activated partial thromboplastin time (APTT) value exceeding 600s; while, the PMETAC hydrogel thin layer could effectively kill attached bacteria. The proposed method provides a new platform to directly modify material surfaces with desired properties, and thus has great potential to be widely used in designing materials for blood purification, drug delivery, wound dressing, and intelligent biosensors.