Fiber Membrane Research Articles

Evaluation with micro-CT of different anticoagulation strategies during hemodialysis in patients with thrombocytopenia: A randomized crossover study.

In patients with enhanced risk for bleeding, heparin-free hemodialysis (HD) with conventional dialyzers is routinely used. To explore the potential benefit of using heparin-coated dialyzers, we used a reference CT-scanning technique and registered different clotting parameters to quantify coagulation with heparin-coated versus non-coated dialyzers. Six HD patients with thrombocytopenia were dialyzed 240min in a randomized crossover study with Evodial 1.3 or FX600 Cordiax, each without anticoagulation. Blood samples were taken from the vascular access predialysis, and from the dialyzer inlet and outlet at 5 and 240min after dialysis start. Predialysis blood samples were analyzed for hemoglobin, hematocrit, thrombocytes, fibrinogen, and activated partial thromboplastin time. On dialyzer inlet and outlet blood samples, a viscoelastic measurement of blood coagulation was performed using a Sonoclot analyzer. After dialysis, dialyzers were visually scored, subsequently dried for 24h, weighed, and scanned with micro-CT at a resolution of 25µm. After image reconstruction, the open, non-coagulated fibers were counted in a representative cross-section at the dialyzer outlet. No sessions were terminated prematurely for circuit clotting. Heparin-coated dialyzers had more patent fibers on micro-CT versus non-coated dialyzers and also had a better score of subjective visual assessment of fiber clotting. There was no difference in subjective assessment of clotting at the venous drip chamber. With both dialyzers, all ACT values remained in the normal range, and were lower at the dialyzer outlet versus inlet. In conclusion, dialysis with a heparin-coated versus non heparin-coated membrane results in substantially less coagulated fibers during 4h hemodialysis without systemic anticoagulation. Eventual leaching of heparin, immobilized on the fiber membrane, does not result in measurable systemic anticoagulation.

Nano Twin-Fiber Membrane with Osteogenic and Antibacterial Dual Functions as Artificial Periosteum for Long Bone Repairing.

Due to the significant role of the periosteum in bone regeneration, we fabricated a novel twin-fiber membrane with antibacterial and osteo-inductive properties as an artificial periosteum by a double spinneret electrospinning method. The antibacterial drug moxifloxacin (MOX) and Chinese medicine icariin (ICA) were introduced into PCL/gelatin and PCL micro/nano fibers respectively to endow the membrane with antibacterial and osteoinduction properties. The twin-fiber structure membrane not only acted as carriers for two different drugs with drastically different solubility in the same fiber membrane, but also achieved stepwise and controlled drug release profiles based on different degradation rates of the two fibers matrix and diffusion rates of the two drugs. Most importantly, only 35% ICA was released out from this dual drug loaded membrane after 1 month and such slow release rate would match with the bone regeneration rate which can hardly be achieved by other drug delivery system. Besides, this dual drug loaded twin-fiber membrane exhibited clear antibacterial effect and excellent in vitro biocompatibility for cells to adhere to and proliferate on. Furthermore, an obvious up-regulation of osteocalcin (OCN), type I collagen (COLI) expression and calcium deposition of MC3T3-E1 cells demonstrated the improved osteogenic differentiation capability. Also, the dual drug loaded twin-fiber membrane displayed fascinating properties contributing to new bone formation in rabbit radius defect model. These results indicate the huge potential of this dual drug loaded twin-fiber membrane as an effective drug release controller and biomimetic multifunctional artificial periosteum to accelerate bone regeneration.

Core-sheath micro/nano fiber membrane with antibacterial and osteogenic dual functions as biomimetic artificial periosteum for bone regeneration applications

The traditional Chinese medicine icariin (ICA) and broad-spectrum antibacterial drug moxifloxacin hydrochloride (MOX) were introduced into a polycaprolactone core and gelatin shell, respectively, to develop osteogenic and antibacterial biomimetic periosteum by coaxial electrospinning. The physical properties, drug release, degradation, antibacterial property, in vitro and in vivo osteogenesis performances were investigated. Results demonstrated that stepwise and controlled drug release profiles were achieved based on the core-shell configuration and disparate degradation rate of PCL and gelatin. Only 20% ICA was released from this dual drug-loaded membrane after 1 month while the release of MOX was almost completed. Moreover, clear in vitro antibacterial effect and enhancement in osteogenic marker expressions including osteocalcin, type-I collagen expression, and calcium deposition were observed. Notably, the dual drug-loaded membrane displayed fascinating properties contributing to in vivo bone formation in terms of quality and quantity in a rabbit radius defect model.

Hierarchical Al2O3/SiO2 fiber membrane with reversible wettability for on-demand oil/water separation

This work presents an effective method of fabricating hierarchical Al2O3/SiO2 fiber membrane with reversible wettability for on-demand oil/water separation. In this strategy, the superhydrophilic/underwater superoleophobic surfaces are fabricated by in-situ growing hierarchical Al2O3 nanosheets on the SiO2 fiber surfaces that can be used as water-removing materials for oil/water separation. Then, the superhydrophobic/oleophilic surfaces are obtained by surface chemical modification with sodium laurate, which can be used as oil-removing materials for oil/water separation. Interestingly, the reversible wettability transformation of Al2O3/SiO2 fiber membrane can be controlled by the annealing and modification treatment alternately. The as-prepared Al2O3/SiO2 fiber membrane, combining the advantages and overcoming disadvantages of two modes, achieves reversible wettability transitions and on-demand oil/water separation. In addition, the Al2O3/SiO2 fiber membrane shows a significant chemical stability and super-wettability even after five annealing and surface modification cycles, indicating its excellent durability. The separation efficiency in both oil-removing mode and water-removing mode is over 95% for various oil/water mixtures through multiple recycle separation processes. This work not only provides a simple and cost-effective method to fabricate separation membrane with reversible wettability, but also shows great potential in remediation of large-scale oil spillage or organic solvents discharge at different environmental conditions.

Manufacturing of superabsorbent membranes of PVA and rice husk fibres reinforced with nanosilica for agricultural and horticultural applications

ABSTRACTNovel superabsorbent membranes (SMs) consisting of polyvinyl alcohol (PVA), cellulose nanocrystals (CNCs) originated from rice husk (RH), nanosilica, glutaraldehyde and glycerine (G) were manufactured by a compression moulding process. RHs were used to isolate pure CNCs via mechanical and chemical treatments. RHs were used to improve water retention. These SMs were characterised by Fourier-transform infrared spectroscopy, scanning electron microscopy, mechanical testing and differential scanning calorimetry. SMs showed a greater equilibrium swelling capacity than neat cross-linked PVA. Moreover, the water transport mechanism of all SMs was found to follow Fickian diffusion. SMs exhibited good pH-dependent swelling reversibility and high-water retention capacity, making them more efficient water retention materials. The biodegradability of SMs was evaluated under environmental changes. The biodegradability of SMs was evaluated against environmental changes. The SM was also investigated for antimicrobial activity against pathogenic bacteria such as Candida albicans (fungus), Bacillus subtilis (Gram-positive), Staphylococcus aureus (Gram-positive), Proteus vulgaris (Gram-negative) and Erwinia carotovora (Gram-negative). SMs have been found to act as a useful water reservoir, which may make it useful in agricultural applications.Abbreviation: Novel superabsorbent membranes (SMs) consisting of polyvinyl alcohol (PVA), cellulose nanocrystals (CNCs) originated from rice husk (RH), nanosilica (NS), glutaraldehyde (GLA) and glycerine (G) were manufactured by a compression moulding process. RHs were used to isolate pure CNCs via mechanical and chemical treatments. RHs were used to improve water retention. These SMs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Mechanical Testing and Differential Scanning Calorimetry (DSC).

Multilevel structural stereocomplex polylactic acid/collagen membranes by pattern electrospinning for tissue engineering

In this work, electrospun membranes of biodegradable polylactic acid and hydrosoluble collagen with multilevel architectures were fabricated by pattern template electrospunning method. The performances influenced by constituent of electrospun matrix and multilevel structures of electrospinning membranes were discussed. The mechanical properties and hydrophilicity were improved both by blending nature collagen and inducing the multilevel structures. The multilevel-architecture membranes were seeded by L929 fibroblast cells with phenotypic shape and guided growth according to pattern orientation. Cells infiltration through the fibers, cell attachment, and proliferation with fiber membranes were observed during the process. More interestingly, for further investigation of promotion the cell infiltration by multilevel structures, the electrospinning membranes were processed into tubular scaffold with 3D print scaffold. The in vivo result confirmed the scaffold favourable biocompatibility and improved tissue regeneration behaviors in vivo. The novel biodegradable membranes and scaffolds will be applicable for tissue engineering based upon their particularly multilevel architectures, which acts to support and guide cell growth in regular way.

Research progress on the role of connective tissue growth factor in fibrosis of diabetic retinopathy.

Diabetic retinopathy (DR) is one of the most important types of diabetic microangiopathy, which is a specific change of fundus lesions and is one of the most serious complications of diabetes. When DR develops to proliferative DR, the main factors of decreasing vision, and even blindness, include retinal detachment and vitreous hemorrhage caused by contraction of blood vessels by fiber membrane. Recent studies reported that the formation of fiber vascular membrane is closely related to retinal fibrosis. The connective tissue growth factor (CTGF) is a cytokine that is closely related to DR fibrosis. However, its mechanism is poorly understood. This paper summarizes the recent studies about CTGF on DR fibrosis for a comprehensive understanding of the role and mechanism of CTGF in PDR.

Application of Fly Ash as an Adsorbent for Removal of Air and Water Pollutants

Air pollutants such as volatile organic compounds (VOCs), nitrogen oxides (NOx), and sulfur dioxide (SO2), as well as water pollutants (e.g., heavy metals phosphorous, fluoride, boron, phenolic compounds, and dyes), are harmful to humans and the environment. Effective control and reduction of their pollution is therefore an important topic for today’s scientists. Fly ash (FA) is a type of industrial waste that can cause multiple environmental problems if discharged into the air. On the other hand, because of its high porosity, large specific surface area, and other unique characteristics, FA can also be used as a low-cost and high efficient adsorbent for treatment of environment pollutants. This paper reviews the effects of FA on treatment of the air and water pollution, including to the current status of global FA utilization, physicochemical properties, principle of adsorption, and the application direction of FA in the future. Since most researchers only studied the adsorption capacity of pure FA or zeolite (synthesized from FA), the research on the fabrication of nanofiber membranes using FA is still lacking, especially the adsorption of VOCs from air and heavy metals from wastewater using FA nanofiber membranes. Therefore, in this paper, we focus on reviewing and summarizing that FA can be spun into a fiber membrane via electrospinning with the ability to adsorb VOCs and heavy metals from air and wastewater. Moreover, we also evaluate the future application value of FA nanofiber membranes in the field of environmental pollution control. Utilization of nanofiber technology to fabricate multi-functional FA emerging composite materials to mitigate air and water pollution has great potential in the future, especially the use of pollutant materials to control other pollutants.

Fiber membrane with orthogonal aligned surface for guided tissue regeneration

A novel guided tissue regeneration (GTR) membrane with orthogonal aligned fibers in surface layers and random fibers within interlayer was developed by multilayer electrospinning. The mechanical strength of tri-layer membrane was between random and aligned membranes. The promotion of the proliferations of MC3T3-E1 and NIH-3 T3 cells on the tri-layer membrane were observed during monoculture. When cells were cocultured, the tri-layer membrane was effective in impeding MC3T3-E1 and NIH-3 T3 cell infiltration by guiding cells to grow along the direction of the fiber alignment.

A 3D heterogeneous FeTiO3/TiO2@C fiber membrane as a self-standing anode for power Li-ion battery

A three-dimensional (3D) networking FeTiO3/TiO2@C flexible fiber membrane was successfully fabricated by an electrospinning process and a controlled hot-press sintering method. This FeTiO3/TiO2@C fiber membrane displays a long-range continuous conductive networks, which can be directly used as self-standing anodes. The electrode sintered at 750 °C for 3 h possesses a reversible capacity of 205.4 mAh/g after 100 cycles at a current density of 300 mA/g. The superior cycle and rate performance can be attributed to the synergistic effect of little volume variation of TiO2 matrix, high capacity of FeTiO3 and good electrical conductivity of 3D networking.

Physical and oxidative stability of functional avocado oil high internal phase emulsions collaborative formulated using citrus nanofibers and tannic acid

Avocado oil-based high internal phase emulsions (HIPEs) were formed and stabilized at by citrus nanofibers (CNFs) and tannic acid (TA) via a simple shear-induced emulsification technique. CNFs/TA colloidal complex (CTNFs) based on the hydrogen-bonding interaction between citrus nanofibers and TA was successfully generated. These complex colloidal nanofibers with enhanced interfacial reactivity can be utilized for the preparation of stable avocado oil-based HIPEs by one-step homogenization. A dense and orderly interfacial architecture via the combination of steric hindrance from fibers membrane and interfacial cargo of TA endowed the emulsions with favorable oxidative stability, evidenced by low lipid hydroperoxides, malondialdehyde and hexanal levels in the emulsions after thermally accelerated storage. The HIPEs are formed as a gel with a texture that can be modulated by adjusting TA concentration. Furthermore, a pH triggered responsible propertie was observed as a result of the pH-dependent bond of TA and citrus nanofibers. These results will likely extend the use of these surfactant-free, and potentially edible emulsions to new food, cosmetic, and pharmaceutical applications.

Water-Resistant Efficient Stretchable Perovskite-Embedded Fiber Membranes for Light-Emitting Diodes.

Cesium lead halide perovskite nanocrystals (NCs) with excellent intrinsic properties have been employed universally in optoelectronic applications but undergo hydrolysis even when exposed to atmospheric moisture. In the present study, composite CsPbX3 (X = Cl, Br, and I) perovskite NCs were encapsulated with stretchable (poly(styrene-butadiene-styrene); SBS) fibers by electrospinning to prepare water-resistant hybrid membranes as multicolor optical active layers. Brightly luminescent and color-tunable hydrophobic fiber membranes (FMs) with perovskite NCs were maintained for longer than 1 h in water. A unique remote FMs packaging approach was used in high-brightness perovskite light-emitting diodes (PeLEDs) for the first time.

Effects of Dopant Types and Contents on Morphology and Strength Properties of PANI/PAN Electrospun Nanofibers

In this paper, the electrospinning of polyaniline under different dopant conditions were studied, the experimental phenomena was introduced, analyzed the relationship between the nanofiber surface morphology of DBSA-PANI/PAN, HCl-PANI/PAN and PTSA-PANI/PAN membranes and dopant type and content. The average diameter of DBSA-PANI/PAN electrospinning fiber membrane showed a decreasing trend when the content of doped polyaniline increased 1%-4%, and reached a minimum value of 780nm when the concentration was 4%. The strength of DBSA-PANI/PAN fiber membrane was the highest when the concentration of doped polyaniline was 1%, and the maximum intensity was 1.8×10 5 Pa. The average diameter of HCl/PANI/PAN fiber membranes decreases with the increase of doped polyaniline concentration, and it fluctuates up and down within a small range. When the content of doped polyaniline was increased to 4%, the average fiber diameter reached a minimum of 420 nm. The strength of the HCl-PANI/PAN fiber membrane was the highest when the concentration of doped polyaniline was 4%, and the maximum intensity was 1.08×10 5 Pa. The average diameter of the PTSA-PANI/PAN electrospun fiber membrane was the smallest at 2% doped polyaniline content and was 430 nm, the strength of PTSA-PANI/PAN fiber membrane is the highest when the content of doped polyaniline is 2%, and the maximum intensity is 3.9×10 4 Pa. In this paper, the basic research of doped polyaniline electrospinning nanofibers has made a useful supplement to the existing research of polyaniline nanofibers, and has a reference value for the application of polyaniline.

聚碳酸亚丙酯(PPC)纤维膜的制备及其热性能研究

聚碳酸亚丙酯(PPC)纤维膜的制备及其热性能研究

Zeolite Incorporated Polycaprolactone/Zeolite Nanocomposite Membranes for Silver Removal

The presence of heavy metals in drinking water leads to several health problems. Nano and micro fiber membranes can be used to overcome this through nano or microfiltration process. In this study, polycaprolactone (PCL)/zeolite electrospun composite membranes were fabricated and characterized. PCL is one of the synthetic polymers used in biomedical applications. It has several advantages, including biocompatibility, biodegradability and mechanical flexibility. On the other hand, zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. Electrospinning is a promising technique to produce membranes by applying high voltage electricity. In this research, an electrospinning technique was used to fabricate the electrospun membrane based on PCL and zeolite. In order to produce electrospun membrane, 15% (w/v) of PCL polymer solution was dissolved in acetone and 20% (w/v) zeolite nanoparticles were incorporated into the PCL polymer solution. The diameter range of fiber was 2-6 µm. Zeolite nanoparticles were distributed homogenously into the fibers. EDX spectrum confirmed the presence of zeolite throughout the membrane. From the performance testing, it was revealed that the membrane can be potentially used as microfiltration to entrap silver contaminants in drinking water. Apart of that, the membranes are prepared with biocompatible, non-toxic materials which can be eco-friendly.

Correction to Synthesis of β-Cyclodextrin-Based Electrospun Nanofiber Membranes for Highly Efficient Adsorption and Separation of Methylene Blue.

Water-insoluble β-cyclodextrin-based fibers were synthesized by electrospinining followed by thermal cross-linking. The fibers were characterized by field-emission scanning electron microscopic (FE-SEM) and Fourier transformed infrared spectrometer (FT-IR). The highly insoluble fraction obtained from different pH values (3-11) indicates successful cross-linking reactions and their usability in aqueous solution. After the cross-linking reaction, the fibers' tensile strength increases significantly and the BET surface area is 19.49 m(2)/g. The cross-linked fibers exhibited high adsorption capacity for cationic dye methylene blue (MB) with good recyclability. The adsorption performance can be fitted well with pseudo-second-order model and Langmuir isotherm model. The maximum adsorption capacity is 826.45 mg/g according to Langmuir fitting. Due to electrostatic repulsion, the fibers show weak adsorption toward negatively charged anionic dye methyl orange (MO). On the basis of the selective adsorption, the fiber membrane can separate the MB/MO mixture solution by dynamic filtration at a high flow rate of 150 mL/min. The fibers can maintain good fibrous morphology and high separation efficiency even after five filtration-regeneration cycles. The obtained results suggested potential applications of β-cyclodextrin-based electrospun fibers in the dye wastewater treatment field.

Hierarchically structured polymeric ionic liquids and polyvinylpyrrolidone mat-fibers fabricated by electrospinning

Different polymeric ionic liquids/polyvinylpyrrolidone (PILs/PVP) fiber membranes were prepared by electrospinning from the corresponding polymeric blends.

Orientation image analysis of electrospun submicro-fibers based on Hough transform and Regionprops function

Popular electrospun technology can only obtain submicron fibers and fiber membranes in random or in slight orientation, in fact, they are not real nanofibers. A fast-rotating drum-collector has been introduced into the electrospinning setup to improve the orientation of electrospun fibers/membranes and, more importantly, to stretch the electrospun fibers. The measured results indicate that: (1) the submicro-fiber orientation and the angle frequency distribution can be characterized quantitatively by Hough transform (HT) and Regionprops function (RF) approaches, and the accuracy of HT is relatively higher than that of RF; (2) through changing the drum speed, an extra stretching force is exerted on the submicro-fibers, so making them thinner; and (3) the higher the drum surface speed, the greater is the orientation of the electrospun fibers, and the finer and stronger the submicro-fibers; their diameter ranges from about 250 nm at zero drum speed to 170 nm at 7 m/min, and may even get into the nanoscale—that is, 1–100 nm.

Aligned poly (glycolide‐lactide) fiber membranes with conducting polypyrrole

Electroactive polypyrrole (PPy) are highly attractive for a number of biomedical applications such as tissue engineering. To improve interfacial compatibility of PPy with biopolyesters, poly (ɛ‐caprolactone) grafted PPy (PPy‐g‐PCL) are synthesized in this work and characterized with Fourier transform infrared and nuclear magnetic resonance. PPy‐g‐PCL exhibits good conductivity and electrochemical activity. It is also blended with poly (glycolide‐lactide) to make aligned fiber membranes via drum at the speed of 1500 r/min. The relationships of blending ratio with the fibrous structure, thermal stability, wettability, and mechanical properties are clarified. The results show that blending PPy‐g‐PCL has no significant effect on the fibrous morphology, but fibers trends aligned architecture as the blend ratio of poly (glycolide‐lactide)/PPy‐g‐PCL exceeds 70/30. The membranous thermal and mechanical stability are modified. The membranous hydrophilicity significantly enhances with PPy‐g‐PCL amount increasing. Then the fiber membrane with topographical and electrical cues is qualified as the application of tissue engineering. Copyright © 2016 John Wiley & Sons, Ltd.

Closely packed x-poly(ethylene glycol diacrylate) coated polyetherimide/poly(vinylidene fluoride) fiber separators for lithium ion batteries with enhanced thermostability and improved electrolyte wettability

Abstract The x-polyethylene glycol diacrylate (x-PEGDA) coated polyetherimide/polyvinylidene fluoride (PEI/PVdF) membranes are obtained by the facile combination of dip-coating and free radical polymerization of PEGDA on the electrospun PEI/PVdF fiber membranes. Successful cross-linking of PEGDA increases the average fibers diameter from 553 to 817 nm and reduces the packing density, which not only increases the tensile strength of x-PEGDA coated PEI/PVdF membranes, but also decreases the average pore diameter. Besides, the x-PEGDA coated PEI/PVdF membranes are endowed with good wettability, high electrolyte uptake, high ionic conductivity and improved electrochemical stability window because of the good affinity of PEI and PEGDA with liquid electrolyte. Benefiting from the synergetic effect of PEI and PVdF, the x-PEGDA coated PEI/PVdF membranes exhibit excellent thermal stability and nonflammability, which are beneficial for enhancing the safety of lithium ion batteries. More importantly, the x-PEGDA coated PEI/PVdF membranes based Li/LiFePO 4 cell exhibits comparable cycling stability with capacity retention of 95.9% after 70 cycles and better rate capability compared with the Celgard membrane based cell. The results clearly demonstrate that the x-PEGDA coated PEI/PVdF membranes are the promising separator candidate with improved wettability and safety for next-generation lithium ion batteries.