Ionic Crosslinking Research Articles

High stretching tuned GO decorated non-shrinkable polyacrylic acid-based composite fiber and its excellent performance as a Fenton catalyst

Mixed valent iron ions were used to create a flexible ionic crosslinking network through coordination, making PAA fiber highly stretchable, and the fiber was highly stretched to tear graphene oxide (GO) sheets into discontinuously-dispersed monolayer sheets. The monolayer sheets could construct many hydrogen bonds with PAA chains to serve as knots to hinder chain movement, controlling the shrinkage of stretched fiber. Co-solvent formamide could improve the heat resistance of PAA fiber through special calorific effect; thus the highly-stretched fiber could tolerate high temperature heat setting. Due to the advanced structure induced by stretching, internal force relaxation caused by heat setting, and the existence of knots, the resulting fiber possessed the features of high strength and no shrinkage. High strength made the fiber mechanically applicable, and the unshrinkability could help it to maintain large specific surface area and strong iron ions-immobilizing capability. As a result, the catalytic activity of non-shrinkable fiber was increased by 25% compared with that of shrinkable fiber for methylene blue (MB) decolorization, and iron ion loading ratio was increased by 174.5%; however, iron ion leaching ratio was decreased by 76.5%, which was conducive to reusability improvement. Thereby, the resulting fiber could be repeatedly used to decolorize MB.

Ambient Pressure Drying of Freeze-Cast Ceramics from Aqueous Suspension.

Freeze-casting has been wildly exploited to construct porous ceramics but usually requires costly and demanding freeze-drying (high vacuum, size limit, and supercooled chamber), which can be avoided by the ambient pressure drying (APD) technique. However, applying APD to freeze-cast ceramic based on an aqueous suspension is still challenging due to inert surface chemistry. Herein, a modified APD strategy is developed to improve the drying process of freeze-cast ceramics by exploiting the simultaneous ice etching, ionic cross-linking, and solvent exchange under mild conditions (-10-0 °C, ambient pressure). This versatile strategy is applicable to various ceramic species, metal ions, and freezing techniques. The incorporated metal ions not only enhance liquid-phase sintering, producing ceramics with higher density and mechanical properties than freeze-cast counterparts, but also render customizable coloration and antibacterial property. The cost-/time-efficient APD is promising for mass production and even successive production of large-size freeze-cast ceramics that exceed the size of commercial freeze-dryers.

Fibrinogen-Based Bioink for Application in Skin Equivalent 3D Bioprinting.

Three-dimensional bioprinting has emerged as an attractive technology due to its ability to mimic native tissue architecture using different cell types and biomaterials. Nowadays, cell-laden bioink development or skin tissue equivalents are still at an early stage. The aim of the study is to propose a bioink to be used in skin bioprinting based on a blend of fibrinogen and alginate to form a hydrogel by enzymatic polymerization with thrombin and by ionic crosslinking with divalent calcium ions. The biomaterial ink formulation, composed of 30 mg/mL of fibrinogen, 6% of alginate, and 25 mM of CaCl2, was characterized in terms of homogeneity, rheological properties, printability, mechanical properties, degradation rate, water uptake, and biocompatibility by the indirect method using L929 mouse fibroblasts. The proposed bioink is a homogeneous blend with a shear thinning behavior, excellent printability, adequate mechanical stiffness, porosity, biodegradability, and water uptake, and it is in vitro biocompatible. The fibrinogen-based bioink was used for the 3D bioprinting of the dermal layer of the skin equivalent. Three different normal human dermal fibroblast (NHDF) densities were tested, and better results in terms of viability, spreading, and proliferation were obtained with 4 × 106 cell/mL. The skin equivalent was bioprinted, adding human keratinocytes (HaCaT) through bioprinting on the top surface of the dermal layer. A skin equivalent stained by live/dead and histological analysis immediately after printing and at days 7 and 14 of culture showed a tissuelike structure with two distinct layers characterized by the presence of viable and proliferating cells. This bioprinted skin equivalent showed a similar native skin architecture, paving the way for its use as a skin substitute for wound healing applications.

Tunable Double-Network GelMA/Alginate Hydrogels for Platelet Lysate-Derived Protein Delivery.

Hydrogels (gels) are attractive tools for tissue engineering and regenerative medicine due to their potential for drug delivery and ECM-like composition. In this study, we use rheology to characterize GelMA/alginate gels loaded with human platelet lysate (PL). We then characterize these gels from a physicochemical perspective and evaluate their ability to transport PL proteins, their pore size, and their rate of degradation. Finally, their biocompatibility is evaluated. We describe how alginate changes the mechanical behavior of the gels from elastic to viscoelastic after ionic (calcium-mediated) crosslinking. In addition, we report the release of ~90% of PL proteins from the gels and relate it to the degradation profile of the gels. Finally, we evaluated the biocompatibility of the gels. Thus, the developed gels represent attractive substrates for both cell studies and as bioactive materials.

Dual reinforced composite membranes from in-situ ionic crosslinked quaternized chitosan filled quaternized polyvinylidene fluoride nanofiber for alkaline direct methanol fuel cell

The main obstacle of high-performance cationic functionalization chitosan (CS) as anion exchange membranes (AEMs) is the trade-off between mechanical stability and ionic conductivity. Here, in-situ ionic crosslinking between the deprotonated hydroxyl group and quaternary ammonium group under alkaline conditions was ingeniously applied to improve the mechanical stability of highly quaternized CS (HQCS) with high IEC (>2 mmol g−1). Meanwhile, to further reduce the swelling and enhance the hydroxide conductivity, a mechanically robust hydroxide ion conduction network, quaternized electrospun poly(vinylidene fluoride) (QPVDF) nanofiber, was subsequently used as the filling substrate of in-situ crosslinked HQCS to prepare dual reinforced thin AEMs. The introduction of a robust QPVDF nanofiber mat can not only greatly improve the mechanical properties and limit swelling, but also create facile ion transport channels. Notably, the HQCS/QPVDF-74.0 composite membrane demonstrates perfect dimensional stability, high mechanical performance and excellent alkaline stability, as well as superior ionic conductivity of 66.2 mS cm−1 at 80 °C. The thus assembled alkaline direct methanol fuel cell displays a maximum power density of 132.30 mW cm−2 using 5 M KOH and 3 M methanol as fuels at 80 °C with satisfactory durability.

Self-healing poly(acrylic acid) hydrogels fabricated by hydrogen bonding and Fe3+ ion cross-linking for cartilage tissue engineering

Self-healing poly(acrylic acid) hydrogels fabricated by hydrogen bonding and Fe3+ ion cross-linking for cartilage tissue engineering

Construction of whey protein gels prepared by three methods to stabilize high internal phase Pickering emulsions loaded with CoQ10 under different pH.

The aim of this study was to investigate the effect of whey protein gel particles (WPGPs) prepared by heat-induced method, enzyme cross-linking method and calcium ion cross-linking method on the structural properties and intrinsic linkage of their stable high internal phase Pickering emulsions (HIPPEs) under different pH conditions. The effects of different pH and preparation methods on the internal interaction forces, particle size, ζ-potential, wettability and secondary structure of gels was investigated. The results indicated that the construction of HIPPEs system was successfully constructed at pH 3, 5 or 7. The WPGPs stabilized HIPPEs can maintain stable state at 4°C for 28days. Coenzyme Q10 (CoQ10) loaded with HIPPEs increased the bioavailability from 13.2% to 79.4%, which was demonstrated in in vitro digestion experiments.

Size‐Selective Ionic Crosslinking Provides Stretchable Mixed Ionic–Electronic Conductors

AbstractMechanically compliant conductors are of utmost importance for the emerging fields of soft electronics and robotics. However, the development of intrinsically deformable organic conductors remains a challenge due to the trade‐off between mechanical performance and charge mobility. In this study, we report a solution to this issue based on size‐selective ionic crosslinking. This rationally designed crosslinking mediated by length‐regulated oligo(ethylene glycol) pendant groups and metal ions simultaneously improved the softness and toughness and ensured excellent mixed ionic–electronic conductivity in poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate composite materials. Moreover, the added ions remarkably promoted accumulation of charge carriers in response to temperature gradient, thus offering a viable approach to stretchable thermoelectric generators with enhanced stability against humidity.

Size-Selective Ionic Crosslinking Provides Stretchable Mixed Ionic-Electronic Conductors.

Mechanically compliant conductors are of utmost importance for the emerging fields of soft electronics and robotics. However, the development of intrinsically deformable organic conductors remains a challenge due to the trade-off between mechanical performance and charge mobility. In this study, we report a solution to this issue based on size-selective ionic crosslinking. This rationally designed crosslinking mediated by length-regulated oligo(ethylene glycol) pendant groups and metal ions simultaneously improved the softness and toughness and ensured excellent mixed ionic-electronic conductivity in poly(3,4-ethylenedioxythiophene):polystyrene sulfonate composite materials. Moreover, the added ions remarkably promoted accumulation of charge carriers in response to temperature gradient, thus offering a viable approach to stretchable thermoelectric generators with enhanced stability against humidity.

Triaxial bioprinting large-size vascularized constructs with nutrient channels

Bioprinting has demonstrated great advantages in tissue and organ regeneration. However, constructing large-scale tissue and organs in vitro is still a huge challenge due to the lack of some strategies for loading multiple types of cells precisely while maintaining nutrient channels. Here, a new 3D bioprinting strategy was proposed to construct large-scale vascularized tissue. A mixture of gelatin methacrylate (GelMA) and sodium alginate (Alg) was used as a bioink, serving as the outer and middle layers of a single filament in the triaxial printing process, and loaded with human bone marrow mesenchymal stem cells and human umbilical vein endothelial cells, respectively, while a calcium chloride (CaCl2) solution was used as the inner layer. The CaCl2 solution crosslinked with the middle layer bioink during the printing process to form and maintain hollow nutrient channels, then a stable large-scale construct was obtained through photopolymerization and ion crosslinking after printing. The feasibility of this strategy was verified by investigating the properties of the bioink and construct, and the biological performance of the vascularized construct. The results showed that a mixture of 5% (w/v) GelMA and 1% (w/v) Alg bioink could be printed at room temperature with good printability and perfusion capacity. Then, the construct with and without channels was fabricated and characterized, and the results revealed that the construct with channels had a similar degradation profile to that without channels, but lower compressive modulus and higher swelling rate. Biological investigation showed that the construct with channels was more favorable for cell survival, proliferation, diffusion, migration, and vascular network formation. In summary, it was demonstrated that constructing large-scale vascularized tissue by triaxial printing that can precisely encapsulate multiple types of cells and form nutrient channels simultaneously was feasible, and this technology could be used to prepare large-scale vascularized constructs.

Self-supported hydrogel loose nanofiltration membrane for dye/salt separation

A novel self-supported hydrogel loose nanofiltration (LNF) membrane was prepared by using sodium alginate as matrix, large molecular weight PEG as pore-making agent, cellulose nanofibers (CNF) and carboxylated multi-walled carbon nanotubes (MWCNT-COOH) as additives, in which free water evaporation (“cooking”) technique followed by ionic cross-linking method was utilized. The “cooking” technique and the addition of CNF and MWCNT-COOH guaranteed the mechanical strength of the gel, and the synergistic effect of large molecular weight PEG and MWCNT-COOH made the gel form a loose structure. The resulting composite membrane possessed high water permeability of 51.6 Lm−2h−1bar−1. Meanwhile, based on the porous structure and the synergistic action of multi-ionic groups, the membrane exhibited a high dye rejection: Crystal violet (99.8%), Congo red (98.9%), Tartrazine (93.1%), Methylene blue (85.7%), while maintaining a rather low retention of salts: MgSO4 (11.6%), Na2SO4 (10.5%), MgCl2 (9.1%), NaCl (7.3%). Furthermore, the membrane exhibited outstanding separation efficiency towards the mixed dye/salt feed solution with special combination. In addition, the membrane not only showed excellent hydrophilicity and stain resistance, but also had good recycling effect. This study provides a simple and feasible method for the preparation of dye desalination membrane.

New insights into the molecular structure and dynamics of a recyclable and ionically crosslinked carboxylated nitrile rubber (XNBR)

Ionic crosslinking offers a route to rubber reprocessability due to ion pairs’ dynamism, with recent studies focusing on tensile properties recovery. However, this research aims to provide, for the first time, a comprehensive overview of the recyclability of carboxylated nitrile rubber (XNBR), spotlighting changes in molecular dynamics through multiple recycling cycles beyond tensile tests. A uniquely recyclable XNBR, incorporating ZnO as a multifunctional additive, was designed alongside a simple, scalable, two-step recycling process. Evidence of the delicate balance between crosslink density and molecular entanglements that affects the dynamics of the recycled material was found. Recycling also restricts the molecular dynamics near ionic domains; attributed to a higher crosslink density (from 3.69×10-5molcm−3 in the pristine sample to 6.00×10-5molcm−3 after the third cycle), caused by a decreased ionic clusters size (aggregation number drops from 12.2 to 6.9). Remarkably, negligible differences (<10%) in compressive fatigue behavior and an enhanced chemical resistance in different solvents (up to 350% increase in motor oil) were also observed, ensuring suitable performance in conditions closer to service. Overall, this study demonstrates the feasibility of XNBR recycling and provides a broad understanding of this material at the molecular level.

Studies on Agrochemical Controlled Release Behavior of Copolymer Hydrogel with PVA Blends of Natural Polymers and Their Water-Retention Capabilities in Agricultural Soil.

Agricultural technical development relies exclusively on the effective delivery of agrochemicals and water to plants and on reducing the harmful effects of agrochemicals on useful organisms in the soil. In this study, super-absorbent hydrogels were prepared in the form of microspheres using gum Arabic (GA), which was copolymerized once with chitosan (CS) and once with poly (vinyl alcohol) (PVA). To impart mechanical strength to the hydrogel microspheres, a covalent cross-linker (N,N'-methylenebisacrylamide (MBA)) was used for the PVA/GA hydrogel, and an ionic cross-linker (sodium hexametaphosphate (SHMP)) was used for the CS/GA hydrogel. The prepared PVA/GA-CH and CS/GA-PH hydrogel microspheres showed different degrees of swelling (DSs) in the following solution media: deionized water (DW), river water (RW), and buffered solutions (pH 4; pH 9). The PVA/GA-CH hydrogel microspheres showed a maximum DS of 84 g/g in the RW, while the CS/GA-PH hydrogel microspheres showed a maximum DS of 63 g/g in the buffered solution at a pH 9. The water-retention capabilities of the hydrogels were studied using a mixture of 0.5% (w/w) hydrogel microspheres in agricultural soil; the composite showed an additional 20 days of water retention in comparison with a control sample consisting of soil alone. The hydrogels were loaded with urea, which is an important fertilizer in the field of agriculture. The PVA/GA-CH hydrogel microspheres showed a maximum loading percentage (Lmax%) of 89% (w/w), while the CS/GA-PH hydrogel microspheres showed an Lmax% = 79.75% (w/w) for urea. The urea-release behaviors of the hydrogel microspheres were studied under different release media and temperature conditions. In practice, the PVA/GA-CH hydrogel microspheres showed a better release profile in the RW at 10 °C, while the CS/GA-PH hydrogel microspheres showed a more controlled release in media at a pH 9 and at 30 °C. The urea-loaded microspheres, aside from those following the release, were characterized via FTIR and SEM. In contrast, virgin microspheres were characterized using XRD,1H NMR, (TGA and DSC), and the maximum degree of swelling, in addition to being subjected to SEM and FTIR analyses.

Alginate hydrogels containing different concentrations of magnesium-containing poly(lactic-co-glycolic acid) microspheres for bone tissue engineering

The easy loss of crosslinking ions in alginate can result in structural collapse and loss of its characteristics as a bone scaffold. A novel injectable tissue engineering scaffold containing poly(lactic-co-glycolic acid) (PLGA) microspheres and alginate was fabricated to improve alginate’s physiochemical and biological properties. MgCO3 and MgO were loaded at a 1:1 ratio into PLGA microspheres to form biodegradable PLGA microspheres containing magnesium (PMg). Subsequently, different concentrations of PMg were mixed into a Ca2+ suspension and employed as crosslinking agents for an alginate hydrogel. A pure Ca2+ suspension was used as the alginate crosslinking agent in the control group. The influence of PMg on the physiochemical properties of the injectable scaffolds, including the surface morphology, degradation rate, Mg2+ precipitation concentration, and the swelling rate, was investigated. MC3T3-E1 cells were seeded onto the hydrogels to evaluate the effect of the resultant alginate on osteoblastic attachment, proliferation, and differentiation. The physicochemical properties of the hydrogels, including morphology, degradation rate, and swelling ratio, were effectively tuned by PMg. Inductively coupled plasma-optical emission spectroscopy results showed that, in contrast to those in pure PMg, the magnesium ions (Mg2+) in alginate hydrogel containing PMg microspheres (Alg-PMg) were released in a dose-dependent and slow-releasing manner. Additionally, Alg-PMg with an appropriate concentration of PMg not only improved cell attachment and proliferation but also upregulated alkaline phosphatase activity, gene expression of osteogenic markers, and related growth factors. These findings indicate that PMg incorporation can regulate the physicochemical properties of alginate hydrogels. The resultant hydrogel promoted cell attachment, matrix mineralization, and bone regeneration. The hydrogel described in this study can be considered a promising injectable scaffold for bone tissue engineering.

Formulation and Evaluation of Mucoadhesive Beads of Dexamethasone

The goal of the current study was to formulate and evaluate mucoadhesive Dexamethasone beads to significantly lengthen the duration of the drug's stay in the GI system to treat Crohn’s disease. Dexamethasone is a corticosteroid that acts as an anti-rheumatic and anti-inflammatory. To decrease the dosage frequency Dexamethasone adhesive beads were formulated for Intimate contact with the underlying absorption surface is made possible by a prolonged stay at the location, which enhances the drug's therapeutic effectiveness. In the current study, calcium chloride and aluminium chloride were utilised as cross-linking agents to create Dexamethasone mucoadhesive beads employing adhesive polymers like sodium alginate, HPMC, and Eudragit L-100. The prepared beads' entrapment efficiencies ranged from 57.15 to 99.16%. Regarding entrapment effectiveness, particle size, surface properties, and in-vitro drug release experiments, the impact of bioadhesive polymers and cross-linking ions was assessed. The MPS-7 delayed the drug's release for 12 hours, which may be related to the cross-linking agent aluminium chloride. According to drug release kinetics, all of the formulations were more linear concerning zero order (r2=0.99) than concerning first order (r2=0.751 to 0.828). Super Case 2 Transport was discovered to be the precise release mechanism.

Pathway modulation and substrate partitioning for CO2-assisted hydration of ethylene oxide catalyzed by swelling poly(ionic liquid)s

Amine-functionalized swellable poly(ionic liquid)s (poly[BAVIm]Br-DVIm-n%) were synthesized by free radical copolymerization of amine-functional vinyl imidazolium ionic liquids and ionic cross-linker 1,8-triethylene glycoldiyl-3,3́-divinylimidazolium (DVIm). Poly[BAVIm]Br-DVIm-n% exhibited excellent swelling ability in the water, ethylene carbonate (EC), and ethylene glycol (MEG), and the swelling ratio (Q) decreased with the increase of the content of the crosslinker. The swollen state of poly[BAVIm]Br-DVIm-2.5% in water observed by cryogenic scanning electron microscopy (cryo-SEM) presented densely packed and interconnected pores (0.2–11 μm). Poly[BAVIm]Br-DVIm-n% were used to catalyze CO2-assisted hydration of ethylene oxide (EO) at a low H2O/EO ratio of 1:1, in which poly[BAVIm]Br-DVIm-2.5% with the highest Q in water gave the highest yield (87%) and selectivity (97%) of MEG. Moreover, EC was produced and subsequently disappeared during the process of CO2-assisted hydration of EO. A cascade reaction including the cycloaddition of CO2 with EO (EO + CO2 → EC) and the hydrolysis of the resulting EC (EC + H2O → MEG + CO2) in situ was elaborated. Poly[BAVIm]Br-DVIm-n% containing amine group and imidazolium ionic liquid synergistically catalyzed this cascade reaction, exhibiting a bifunctional effect. Poly[BAVIm]Br-DVIm-2.5% with the H2O, EC, and MEG enrichment ability in H2O/EO, EC/EO, and MEG/EO could spatially isolate EO and H2O, EC, MEG. The substrate partitioning of poly[BAVIm]Br-DVIm-2.5% could promote the two sequential reactions to be orthogonal and inhibit the side-reactions between MEG and EO, thus resulting in a higher reaction rate of poly[BAVIm]Br-DVIm-2.5% (0.0141 h−1) than that of homogeneous catalyst ([BAVIm]Br) (0.0074 h−1). Furthermore, poly[BAVIm]Br-DVIm-n% had good generality and could be reused effectively at least seven times without a significant decrease of its initial activity.

Ceftazidime-assisted synthesis of ultrasmall chitosan nanoparticles for biofilm penetration and eradication of Pseudomonas aeruginosa

Pseudomonas aeruginosa (P. aeruginosa) infections present a grave threat to immunocompromised individuals, particularly those with cystic fibrosis due to the development of bacterial biofilms. In this study, we engineered self-assembling chitosan-ceftazidime nanoparticles (CSCE) capable of effectively penetrating biofilms and eradicating P. aeruginosa. The CSCE nanoparticles were synthesized through ionic cross-linking, combining negatively charged ceftazidime with positively charged chitosan, resulting in uniform nanoparticles measuring approximately 40 nm in diameter, exhibiting high dispersity and excellent biocompatibility. Remarkably, these nanoparticles exhibited significant inhibition of P. aeruginosa growth, reduced pyocyanin production, and diminished biofilm formation, achieving a maximum inhibition rate of 22.44%. Furthermore, in vivo investigations demonstrated enhanced survival in mice with abdominal P. aeruginosa infection following treatment with CSCE nanoparticles, accompanied by reduced levels of inflammatory cytokines Interleukin-6 (125.79 ± 18.63 pg/mL), Interleukin-17 (125.67 ± 5.94 pg/mL), and Tumor Necrosis Factor-α (135.4 ± 11.77 pg/mL). Critically, mice treated with CSCE nanoparticles showed no presence of bacteria in the bloodstream following intraperitoneal P. aeruginosa infection. Collectively, our findings highlight the potential of these synthesized nanoparticles as effective agents against P. aeruginosa infections.

Image-based assessment and machine learning-enabled prediction of printability of polysaccharides-based food ink for 3D printing

Despite the growing demand and interest in 3D printing for food manufacturing, predicting printability of food-grade materials based on biopolymer composition and rheological properties is a significant challenge. This study developed two image-based printability assessment metrics: printed filaments’ width and roughness and used these metrics to evaluate the printability of hydrogel-based food inks using response surface methodology (RSM) with regression analysis and machine learning. Rheological and compositional properties of food grade inks formulated using low-methoxyl pectin (LMP) and cellulose nanocrystals (CNC) with different ionic crosslinking densities were used as predictors of printability. RSM and linear regression showed good predictability of rheological properties based on formulation parameters but could not predict the printability metrics. For a machine learning based prediction model, the printability metrics were binarized with pre-specified thresholds and random forest classifiers were trained to predict the filament width and roughness labels, as well as the overall printability of the inks using formulation and rheological parameters. Without including formulation parameters, the models trained on rheological measurements alone were able to achieve high prediction accuracy: 82% for the width and roughness labels and 88% for the overall printability label, demonstrating the potential to predict printability of the polysaccharide inks developed in this study and to possibly generalize the models to food inks with different compositions.

Preparation and performance of degradable slow-release fertilizer coating material by a new ionic crosslinked hydrogel material

We report a hydrogel with 25 % polyacrylic acid by grafting and mixing starch with polyacrylic acid and urea. The novel ionic crosslinking strategy through iron ions enabled the high biodegradability of a novel slow-release fertilizer coating material. The ionic cross-linking improved the degree of polymerization of the material and formed a compact structured membrane material, which extended the period of nitrogen release to a sufficient extent. The membrane material obtained through ionic cross-linking exhibited a low thermal decomposition temperature and high thermal weight loss. Material displayed significant degradation with a weight loss of 71.11 % in a 60-day degradation experiment conducted in soil. This cross-linking approach provides a novel route for developing encapsulated slow-release fertilizers. It expands the application of natural polymers in the field of slow-release fertilizers.

Characterization of a chlorine resistant and hydrophilic TiO2/calcium alginate hydrogel filtration membrane used for protein purification maintaining protein structure

The development of membranes for protein purification has stringent requirement of disinfection resistance, low protein adsorption and anti-fouling, without changing protein structure. In this study, hydrophilic titanium dioxide (TiO2)/calcium alginate (TiO2/CaAlg) hydrogel membranes were prepared by a simple ionic cross-linking method. The effects of the porogenic agent polyethylene glycol (PEG) concentration, the molecular weight of PEG, and the concentration of TiO2 on the filtration properties were systematically investigated. The TiO2/CaAlg membrane exhibited excellent bovine serum albumin (BSA) rejection and anti-fouling properties. The mechanical properties and surface energy of the TiO2/CaAlg membrane were significantly improved. The chemical bonding mechanism of TiO2 and NaAlg was investigated by molecular dynamic simulation. The TiO2/CaAlg membrane had good chlorine resistance and could be disinfected or cleaned with sodium hypochlorite. The TiO2/CaAlg hydrogel membrane loaded with polyhydroxybutyrate (PHB) nanofibers maintained high flux (136.7 L/m2h) and high BSA rejection (98.0 %) at 0.1 MPa. The results of circular dichroism and synchronous fluorescence indicated that the secondary structure of BSA was maintained after membrane separation. This study provides one method for the preparation of green and environmentally friendly membrane for protein purification.