Bicomponent Nanofibers Research Articles

Optimization of Diclofenac-Loaded Bicomponent Nanofibers: Effect of Gelatin on In Vitro and In Vivo Response.

The use of electrospun fibers as anti-inflammatory drug carriers is currently one of the most interesting approaches for the design of drug delivery systems. In recent years, biodegradable polymers blended with naturally derived ones have been extensively studied to fabricate bioinspired platforms capable of driving biological responses by releasing selected molecular/pharmaceutical signals. Here, sodium diclofenac (DicNa)-loaded electrospun fibers, consisting of polycaprolactone (PCL) or gelatin-functionalized PCL, were studied to evaluate fibroblasts' in vitro and in vivo response. In vitro studies demonstrated that cell adhesion of L929 cells (≈70%) was not affected by the presence of DicNa after 4 h. Moreover, the initial burst release of the drug from PD and PGD fibers, e.g., 80 and 48%, respectively, after 5 h-combined with its sustained release-did not produce any cytotoxic effect and did not negatively influence the biological activity of the cells. In particular, it was demonstrated that the addition of gelatin concurred to slow down the release mechanism, thus limiting the antiproliferative effect of DicNa, as confirmed by the significant increase in cell viability and collagen deposition after 7 days, with respect to PCL alone. In vivo studies in a rat subcutaneous model also confirmed the ability of DicNa-loaded fibers to moderate the inflammatory/foreign body response independently through the presence of gelatin that played a significant role in supporting the formation of small-caliber vessels after 10 days of implantation. All of these results suggest using bicomponent fibers loaded with DicNa as a valid therapeutic tool capable of supporting the wound healing process and limiting in vivo inflammation and rejection phenomena.

Mini-review of the bi-component nanofibrous scaffolds and drug delivery applications

Drug delivery systems perform to improve the drug's efficacy and heal the affected region. Electrospun nanofibers are strong drug carriers as a scaffold due to their high specific surface area, easy processing, lightweight material. Fibrous scaffolds encapsulating functional bioactive agents are important for drug delivery applications, and they show higher encapsulation efficiency and higher drug loading capacity than various types of carrier materials such as hydrogels, micro/nanobeads, films, conventional fibers, and sponges. In comparison to conventional electrospinning, bi-component electrospinning where drug loading does not occur largely on the surface of the polymer matrix, core-shell nanofibers showed delayed release and a decrease in burst release because the drug was loaded into the core layer. The purpose of this mini-review is to investigate the production and applications of the drug-loaded bi-component nanofibers in structure core-shell, side-by-side, hollow nanofibers, and also emulsion nanofibers using co-axial nozzles. Further, the parameters which influence of these electrospinning process, such as working conditions and polymer properties, as well as drug delivery profile of the resulting nanofibers, have been outlined briefly. The limited clinical studies on the nanofibers have been discussed. Eventually, perspectives on the problems, possibilities, and new approaches for electrospinning advancements have been presented, as well.

The Production of Hollow Nanofibers from PBS / TPU Blends by Coaxial Electrospinning Method

In this study, the production of hollow Polybutylene Succinate (PBS)/Thermoplastic Polyurethane (TPU) nanofibers as biodegradable nanomaterials with improved mechanical properties were carried out by coaxial electrospinning method. The polymer solutions of pure PBS, pure TPU, and PBS/TPU blends (60/40, 40/60, 20/80 w/w) (as the shell) versus pure Polyvinylpyrrolidone (PVP) (as core) were put together for bi-component nanofibers production. The core structure of nanofibers was dissolved in distilled water. Thus, hollow nanofibers were obtained with the removal of PVP from the structure. Characterization studies (SEM, FTIR, and Tensile tests) of hollow nanofibers were performed. The morphological properties of PBS/TPU blends in ratios of 60/40 and 20/80 were observed as homogeneous and non-adhered fiber structures. It was determined that the hollow PBS/TPU (60/40) mat has the thinnest nanofibers. New bond formations within the interactions of substances as studied in the chemistry of blended electrospun webs were examined with FTIR analysis. Therewithal, this test showed the removal of PVP in the core of all nanofibers. It was observed that the adhered fibers increased the tensile stress and decreased the tensile strain at mechanical test results that were verified also by SEM views. It is suggested that the hollow nanofibers produced by this study can be used in the biomedical field as a biodegradable and breathable wound dressing.

Electrospun PVDF-HFP/PAN bicomponent nanofibers as separators in lithium-ion batteries with high thermal stability and electrolyte wettability

Electrospun PVDF-HFP/PAN bicomponent nanofibers as separators in lithium-ion batteries with high thermal stability and electrolyte wettability

The PLA-Ag NPs/PU bicomponent nanofiber production for wound dressing applications: Investigation of core/shell displacement effect on antibacterial, cytotoxicity, mechanical, and surface properties

In this study, pure polyurethane (PU) and poly (lactic) acid-silver nanoparticle (PLA-Ag NP) bicomponent nanofibers were successfully obtained alternately by using in the core or shell with coaxial electrospinning. The effects of displacements in the core and shell of fibers on the characterization, antibacterial, and cytotoxicity properties of whole bicomponent fibers were examined in detail. Using PLA-Ag NPs in the core, produced bicomponent mats that were thinner whereas locating PLA-Ag NPs to the shell, obtained bicomponent nanofibers that were more hydrophobic. TEM and FTIR analysis proved that PLA-Ag NPs and pure PU are obtained as a bicomponent structure without mixing with each other. When pure PU was used in the core, bicomponent mats showed high elasticity and strength. As the Ag NPs ratio in the core has increased, the viability of the mouse fibroblast cell line (L929) also has increased. The bicomponent nanofiber with 10% Ag NP in its core has supported cell growth and has shown a high antibacterial effect against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. This study reported that prepared mats could be used as an antibacterial wound dressing, especially for dry wounds, if renewed every 24 hours.

Preparation of electrospun cellulose acetate/polyethylene imine bicomponent nanofibers for CO2 capture

Preparation of electrospun cellulose acetate/polyethylene imine bicomponent nanofibers for CO2 capture

Polyacrylonitrile (PAN)/Polyvinyl Alcohol (PVA) Electrospun Nanofibrous Membranes Synthesis, Characterizations, and their Air Permeability Properties

In the research described here polyacrylonitrile (PAN)/polyvinyl alcohol (PVA) bicomponent nanofibers (NFs) were produced with different PVA content (10, 20, and 30 wt%) by an electrospinning method and tested for air filtration application. Morphological, structural, and physical properties of the PAN/PVA NFs were analyzed with scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Brunauer–Emmett–Teller (BET) characterization methods. The results showed that regular and beadless PVA NF synthesis was achieved for 10 and 20 wt% of PVA contents. Besides, 10 wt% PVA provided thinner diameter NFs, and the pore size of their membranes was also smaller compared to those of NFs containing 20 wt% PVA. Therefore, PAN/PVA nanofibrous membranes containing 10 wt% PVA with smaller pore size and thinner fiber diameter provided the lowest air permeability.

Side-by-Side Construction of Bi-Component Heterojunctional Nanofibers for High-Performance Gas Sensors: Improvement in Synergistic Effect

Side-by-Side Construction of Bi-Component Heterojunctional Nanofibers for High-Performance Gas Sensors: Improvement in Synergistic Effect

Bicomponent PLA Nanofiber Nonwovens as Highly Efficient Filtration Media for Particulate Pollutants and Pathogens.

Herein, a novel form of bicomponent nanofiber membrane containing stereo-complex polylactic acid (SC-PLA) was successfully produced by the side-by-side electrospinning of Poly (L-lactic acid) (PLLA) and Poly (D-lactic acid) (PDLA). We demonstrate that through these environmentally sustainable materials, highly efficient nanofiber assemblies for filtration can be constructed at very low basis weight. The physical and morphological structure, crystalline structure, hydrophobicity, porous structure, and filtration performance of the fibrous membranes were thoroughly characterized. It was shown that the fabricated polylactic acid (PLA) side-by-side fiber membrane had the advantages of excellent hydrophobicity, small average pore size, high porosity, high filtration efficiency, low pressure drop as well as superior air permeability. At the very low basis weight of 1.1 g/m2, the filtration efficiency and pressure drop of the prepared side-by-side membrane reached 96.2% and 30 Pa, respectively. Overall, this biomass-based, biodegradable filtration material has the potential to replace the fossil fuel-based polypropylene commercial meltblown materials for the design and development in filtration, separation, biomedical, personal protection and other fields.

Dissymmetric interface design of SnO2/TiO2 side-by-side bi-component nanofibers as photoanodes for dye sensitized solar cells: Facilitated electron transport and enhanced carrier separation

SnO2/TiO2 type II heterojunctions are often introduced to enhance the separation efficiency of photogenerated carriers in photoelectrochemical electrodes, while most of these heterojunctions are of core–shell structure, which often limits the synergistic effect from the two components. In this work, dissymmetric SnO2/TiO2 side-by-side bi-component nanofibers (SBNFs) with tunable composition ratios have been prepared by a novel needleless electrospinning technique with two V-shape connected conductive channels (V-channel electrospinning). Results show that this V-channel electrospinning technique is more stable, controllable and tunable for the large-scale preparation of SBNF materials compared to the traditional electrospinning using two side-by-side metal needles. And these SnO2/TiO2 SBNFs are dissymmetric and comprised of a tiny SnO2 NF (tunable diameter within 20–80 nm) and a Sn-doped TiO2 NF (diameter of ~ 250 nm) with a side-by-side structure. Moreover, the dye-sensitized solar cells (DSSCs) based these dissymmetric SnO2/TiO2 SBNFs show the maximum power conversion efficiency (PCE) of 8.3%, which is 2.59 times that of the ones based on the TiO2 NFs. Series of analyses indicate that the enhancements in PCE could mainly be due to the improved electron transport via SnO2 NFs and the enhanced carrier separation via dissymmetric SnO2/TiO2 heterojunction interface. This research will give some new insight in the preparation of SBNFs for high-performance photoelectrochemical devices.

Bicomponent nanofibers from core–shell nozzle in gas jet spinning process

ABSTRACTThis work evaluates the use of a core–shell nozzle assembly in conjunction with gas jet spinning technique for production of bicomponent nanofibers from an immiscible polymer pair of polyvinylpyrrolidone (PVP) and poly(vinyl acetate) (PVAc) with three morphological forms—interpenetrating network (IPN), core–shell, and bilobal structurers—by varying the sets of miscible solvents offering different affinity for the polymers. Such fiber structures have strong potential in drug delivery and wound dressing applications. Solutions of PVP and PVAc in respective single solvents metered through a core–shell nozzle assembly meet at the exit of the nozzle and a liquid jet is initiated upon contact with a turbulent gas jet. The gas jet stretches the liquid jet into nanofibers. The results indicate that miscible solvent pairs with low affinity for one of the polymer component yield core–shell morphology with distinct polymer interfaces, while the miscible solvent pairs with high affinity for both polymers produce IPN morphology. Also, interchanging core and shell solutions does not alter the IPN morphology. Finally, bilobal nanofiber structures result from spinning of polymer solutions in miscible solvents with low affinity for the second polymer using a nonconcentric core–shell nozzle assembly. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48901.

A novel 3D nanofibrous aerogel-based MoS2@Co3S4 heterojunction photocatalyst for water remediation and hydrogen evolution under simulated solar irradiation

The integration of nanostructured photocatalysts into 3D ordered assemblies holds great promise for boosting their dispersibility and stability, and thus allows for the development of competitive strategies for enhancing their photocatalytic performance for various applications. In addition, heterostructure construction for photocatalysts is another effective method to improve their catalytic activity because of the remarkable role the heterostructure plays in charge separation. In this study, a dual-templated method for fabricating molybdenum disulfide@cobaltosic sulfide on nanofibrous aerogel (MoS2@Co3S4/NFA) was effectively used. The NFA carrier comprising bi-component nanofibers was successfully used as the first step template for in-situ growth of ZIF-67. Moreover, ZIF-67 could convert into Co3S4 and be used as the second template for MoS2. The MoS2@Co3S4/NFA delivered excellent photocatalytic activity toward typical contaminants (Cr(VI), sulfamethoxazole, and bacteria), and good hydrogen evolution activity. This paper describes a novel photocatalyst design strategy and opens new horizons for solving environmental and energy issues.

Nano-Crystalline Sandwich Formed in Polylactic Acid Fibers.

Fibers have traditionally been made through melt or solution processes from macromolecules. Most of these fibers have crystalline domains where the segregation of different crystalline features is extremely difficult due to the statistical nature of the formation and growth of these domains. A fibrous nano-crystalline sandwich is reported where distinctly different crystalline regions are formed in layers along the continuous fiber direction during the spinning process and locked in place. This approach employs side-by-side bicomponent nanofiber electrospinning where the components are the enantiomeric pair of poly(l-lactic acid) and poly(d-lactic acid). The formation of the poly(lactic acid) (PLA) stereo-complexes at the junction interphase of the two components is demonstrated through diffusion, which subsequently crystallize into continuous sandwich domains. The stereo-complex crystalline core in the fiber possesses a melting point 50 °C higher than, and properties substantially different from, the regular PLAs at the fringe areas of the fiber. This nano-crystalline sandwich fiber structure can be scaled to the micrometers in a commercial bicomponent process.

CNT Incorporated Polyacrilonitrile/Polypyrrole Nanofibers as Keratinocytes Scaffold

Polypyrrole (PPy) is an attractive scaffold material for tissue engineering with its non-toxic and electrically conductive properties. There has not been enough information about PPy usage in skin tissue engineering. The aim of this study is to investigate biocompatibility of polyacrilonitrile (PAN)/PPy nanofibrous scaffold for human keratinocytes. PAN/PPy bicomponent nanofibers were prepared by electrospinning, in various PPy concentrations and with carbon nanotube (CNT) incorporation. The average diameter of electrospun nanofibers decreased with increasing PPy concentration. Further, agglomerated CNTs caused beads and disordered parts on the surface of nanofibers. Biocompatibility of these PAN/PPy and PAN/PPy/CNT scaffolds were analyzed in vitro. Both scaffolds provided adhesion and proliferation of keratinocytes. Nanofiber diameter did not significantly influence the morphology of cells. However, with increasing number of cells, cells stayed among nanofibers and this affected their shape and size. In this study, we demonstrated that PAN/PPy and PAN/PPy/CNT scaffolds enabled the growth of keratinocytes, showing their biocompatibility.

Multi-networked nanofibrous aerogel supported by heterojunction photocatalysts with excellent dispersion and stability for photocatalysis

A 3D nanofibrous aerogel with low-density, super-hydrophilicity and excellent stability is constructed using bi-component nanofibers via H-bonds.

Efficient Synthesis of PVDF/PI Side-by-Side Bicomponent Nanofiber Membrane with Enhanced Mechanical Strength and Good Thermal Stability.

Bicomponent composite fibers, due to their unique versatility, have attracted great attention in many fields, such as filtration, energy, and bioengineering. Herein, we efficiently fabricated polyvinylidene fluoride/polyimide (PVDF/PI) side-by-side bicomponent nanofibers based on electrospinning, which resulted in the synergism between PVDF and PI, and eventually obtained the effect of 1 + 1 > 2. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the morphology and chemical structure of nanofibers, indicating that a large number of side-by-side nanofibers were successfully prepared. Further, the thermal stability, mechanical strength, and filtration properties of PVDF/PI were carefully investigated. The results revealed that the bicomponent nanofibers possessed both good mechanical strength and remarkable thermal stability. Moreover, the mechanical properties of PVDF/ PI were strengthened by more than twice after the heat treatment (7.28 MPa at 25 °C, 15.49 MPa at 230 °C). Simultaneously, after the heat treatment at 230 °C for 30 min, the filtration efficiency of PVDF/PI membrane was maintained at about 95.45 ± 1.09%, and the pressure drop was relatively low. Therefore, the prepared PVDF/PI side-by-side bicomponent nanofibers have a favorable prospect of application in the field of medium- and high-temperature filtration, which further expands the application range of electrospun fiber membranes.

Development of heat storing poly(acrylonitrile) nanofibers by coaxial electrospinning

New thermal energy storage materials were developed as poly(acrylonitrile) (PAN) nanofibers with encapsulated phase change materials (PCMs). Sixteen samples composed of PAN shells and PEG or PEGME cores, and one control sample composed of only a PAN shell, were manufactured by coaxial electrospinning. SEM images revealed the formation of randomly distributed, distinct nanofibers with smooth surfaces and cylindrical shapes along their lengths. FTIR results confirmed bicomponent nanofiber structures and TGA results demonstrated their thermal stabilities. Phase change performances of nanofibers were repeatedly examined by DSC analyzes; heating enthalpies ranged from 38 to 133 J g−1 and from 29 to 60 J g−1 for PAN-PEGs and PAN-PEGME samples, respectively, corresponding to good encapsulation efficiencies. These remarkable thermal energy storages were achieved at different melting temperatures (−1 to 60 °C). Textile based sandwich structures containing three different types of PAN-PCM nanowebs demonstrated enhanced thermal properties and buffering function against temperature changes in surrounding.

Effect of Solvent Volatility on Diameter Selection of Bicomponent Nanofibers Produced by Gas Jet Fiber Process Test

Abstract This paper addresses the role of solvent volatility on diameter selection of bicomponent polymer nanofibers produced via gas jet fibers (GJF) process whereby an axisymmetric turbulent gas jet is used for liquid jet initiation, liquid jet stretching, and solvent evaporation. Several morphological forms, such as interpenetrating network (IPN), bi-lobal, and core-shell are obtained by spinning homogeneous solutions of two immiscible polymers in two mutually miscible solvents. The diameter selection of fibers of the same morphology, e. g., bi-lobal, is achieved by spinning polymer solutions of two sets of solvents of different volatility. The results show that fiber diameter is strongly dependent on the value of vapor pressure of the solvents while the morphology is strongly dependent on the vapor pressure difference of the two respective solvents. The diameter selection by GJF process is most prominent for IPN nanofibers, moderately prominent for core-shell fibers, and almost indifferent for bi-lobal nanofibers. The relative rates of solvent evaporation are useful in interpreting the experimental trend.

Immobilization of horseradish peroxidase on electrospun poly(vinyl alcohol)–polyacrylamide blend nanofiber membrane and its use in the conversion of phenol

Electrospun nanofibers, with their porous structures, high surface-to-volume ratio, and good mechanical properties, are used as a support material for enzyme immobilization. In this study, the poly(vinyl alcohol) and polyacrylamide bicomponent (PVA–PAAm) nanofibers were fabricated via the electrospinning method. Synthesized PAAm was characterized with size exclusion chromatography (SEC). Nanofibers were characterized by fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscope (SEM). DSC and TGA analyses showed that the nanofibers were more durable than PVA and PAAm polymers. SEM images demonstrated that all nanofibers possessed uniform and smooth structures (average diameter about 300 nm). FTIR results have shown that PAAm successfully participates in nanofiber structure. The produced nanofibers were used as support material for covalent immobilization of horseradish peroxidase (HRP). The optimum temperature for free HRP was 45 °C, whereas it was 50 °C for the immobilized enzyme. The immobilized HRP showed better storage and thermal stability than free HRP. The kinetic parameters (K m and V max) were found to be 2.42 mM and 0.027 U for the immobilized HRP and 1.86 mM and 0.079 U for the free HRP, respectively. The immobilized enzyme could be used effectively for 25 cycles with 54% retention of the activity. The immobilized HRP was also used for the conversion of phenol. Phenol removal was found to be about 29.68% at 180 min in real wastewater. The novel PVA–PAAm nanofibrous material was successfully used as a support material for covalent immobilization of HRP. Immobilized enzymes such as oxido-reductases onto the PVA–PAAm bicomponent nanofiber could be recommended in the treatment of organic pollutants in industrial effluents.

Influence of secondary stretching on diameter and morphology of bicomponent polymer nanofibers produced by gas jet fiber process

This paper focuses on the effect of addition of a secondary gas jet on diameter and morphology of bi-component nanofibers produced using the gas jet fibers (GJF) process. In GJF process, a primary turbulent gas jet is used for liquid jet initiation, liquid jet stretching, and drying of the liquid jet into nanofibers. The secondary gas jet is added to provide additional stretching of the liquid jet so that fibers of even smaller diameter can be obtained. The location of the secondary jet in relation to the liquid delivery nozzle is varied to determine an area of influence of the secondary gas jet on fiber diameter and fiber morphology. The radius of the copper loop used to deliver the secondary gas jet is also varied to assess its effect on fiber diameter. The results show almost 100% reduction in nanofiber diameter of bi-lobal and interpenetrating network type nanofibers with appropriate placement of the secondary gas jet. The additional stretching also creates gradient morphology promoted by incomplete phase separation of the polymers as a consequence of much faster solvent loss.