Simultaneous Electrospinning Research Articles

Quantitative XPS analysis of amine-terminated dendritic functionalized halloysite nanotubes decorated on PAN nanofibrous membrane and adsorption/filtration of Cr(VI)

Quantitative XPS analysis of the active functional groups on the surface of nanofiber membranes is an important issue for evaluating the potential efficiency of the membranes in removing heavy metals from aqueous solutions. This research is developing a novel composite nanofiber for accessibility adsorption groups on the surface of the electrospun membrane for effective removal of Cr(VI). For this purpose, three generations (G1, G2, and G3) of poly(amidoamine) dendrimers (PAMAM) were grafted onto the surface of halloysite nanotubes (HNTs). Functionalized HNTs (F-HNTs) were decorated on the surface of polyacrylonitrile (PAN) nanofiber layers in different ratios by simultaneous electrospinning and electrospraying techniques. The results showed that the decoration with F-HNTs made the surface of the membranes superhydrophilic. The removal efficiency of the optimal sample with 10 % third-generation F-HNTs (PAN/HNTs-G3-10 %) reached 96 % within 5 min. The mechanism for the removal of Cr(VI) ions in the PAN/HNTs-G3-10 % membrane was electrostatic interaction, chelation, and reduction. X-ray photoelectron spectrometer (XPS) analysis was used to characterize the quantitative and qualitative correlation dependencies between the removal of Cr(VI) and the amine functional groups of different generations decorated onto the electrospun layer. Quantitative analysis of the amine-terminated dendritic groups has revealed that the percentage of Cr(VI) removal is proportional to the number of terminal amine groups. Furthermore, PAN/HNTs-G2 and PAN/HNTs-G3 composite nanofiber membranes showed significantly lower leachability of nanoparticles and higher mechanical strength compared to other membranes due to the formation of ionic bonds between the amine-terminated dendritic of HNTs-G2 and HNTs-G3 and the cyanide groups of PAN. Effects of competing heavy metal ions on Cr(VI) adsorption follow the order of Zn(II) > Cu(II) > Ni(II).

Smart Antifouling and Self‐Cleaning Membrane for Effective Oil/Water Separation

AbstractA novel membrane consisting of cellulose acetate (CA) nanofibers and poly(N‐isopropylacrylamide) (PNIPAM) microparticles is successfully fabricated by simultaneous electrospinning and electrospraying. The CA/PNIPAM membrane has highly effective gravity‐driven separation performances for both oil/water mixtures and oil‐in‐water emulsions. It separates oil droplets from oil‐in‐water mixtures and oil‐water emulsions with rejection rates of 99.83% and 96%, respectively. In order to examine the contribution of PNIPAM particles, the performance of the CA/PNIPAM membrane is compared with the CA membrane. Increased hydrophilicity due to the inclusion of the PNIPAM particles between CA nanofibers results in a higher rejection ratio and superior antifouling performance. While the CA membrane becomes unusable after 10 cycles during the separation of the oil–water emulsion, the CA/PNIPAM membrane is still in good shape after 20 cycles. The self‐cleaning ability of the membrane is examined through the permeation flux below and above the lower critical solution temperature (LCST) of PNIPAM. The reversible thermo‐responsive flux variation proves that the pore sizes increase at temperatures above the LCST of PNIPAM. Moreover, when the lubricating oil–water emulsion is filtered through the membrane, the permeate changes from clear to turbid due to the nonretained oil particles as the temperature passes through the LCST.

Fabrication of PAN/PA6//rGO‐TiO2 electrospun nanofibers membrane with self‐cleaning performance under visible‐light

AbstractRegenerative photocatalytic membranes have gained considerable attention for both their unique properties and practical applications in energy and environmental areas. Reduced graphene oxide‐ titanium dioxide (rGO‐TiO2) electrosprayed onto an electrospun PAN/PA6 for photocatalytic and antifouling experiments. The prepared nanohybrid and membrane a were characterized using FESEM, TEM, AFM, EDX, XRD and DRS techniques. Simultaneous electrospinning of PAN and PA6 increased the mechanical strength of nanofibers by 85%. The rGO‐TiO2 caused increased hydrophilicity, wettability, and ultrahigh water flux up to 1885 Lm−2 h−1 in the fabricated membrane. The membrane has good rejection ratio for methylene blue and the photodegradation of MB can occur in the presence of visible light (λ = 440–830 nm) and can recover its permeability. The fabricated structure, has the lowest total and irreversible membrane fouling ratio, giving the membrane higher antifouling and self‐cleaning properties.

(Invited) Bipolar Membranes with a 3D Junction of Interlocking Electrospun Fibers

Bipolar membranes (BPMs), typically laminated layers of anion-exchange and cation-exchange polymers, have the unique capability of splitting water at a potential near 0.83 V. Such membranes are used in electrodialysis membrane separation processes. They also have applications in water electrolyzers, CO2 electrolysis cells, and self-humidifying fuel cells. We report here on recent developments regarding BPMs with a high interfacial area, 3D nanofiber junction.Membranes were prepared by first creating a bipolar junction layer, by the simultaneous electrospinning of anion-exchange and cation-exchange polymers, with the addition of catalyst nanoparticles to facilitate water splitting. Solvent vapor exposure and hot-pressing closed all interfiber pores, to create a dense film of interpenetrating and interlocking nanofibers of positively and negatively charged polymers. In one fabrication method, dense films of solution cast anion and cation-exchange polymers were hot-pressed onto the opposing surfaces of the junction layer to create a tri-layer BPM. Membranes were also fabricated by electrospinning all three layers of the BPM: first spinning anion-exchange fibers, followed by dual fiber spinning with catalyst spraying, and then spinning only cation-exchange fibers. Solvent exposure and hot-pressing closed all interfiber voids.BPMs were made with a junction layer 12-15 mm thick, where the total membrane thickness was 50-80 mm. Membranes were prepared with both hydrocarbon and fluoropolymer ionomers, e.g., sulfonated poly(ether ether ketone) or perfluorosulfonic acid as the cation-exchange polymer and either quaternized poly(phenylene oxide), AEMIONä (an imidazolium-based polymer sold by Ionomr Innovations, Inc.), or PiperION (a poly(aryl piperidinium) from Versogen) as the anion-exchange polymer. A variety of different junction layer catalysts powders were examined, including Al(OH)3 and graphene oxide. Membranes were evaluated in an H-cell for the collection of steady-state current-voltage data and in a flow cell for long-term constant current water splitting (electrolysis) operation, typically with an aqueous Na2SO4 electrolyte. The 3D junction membranes performed exceptionally well: (i) the water splitting potential was low (near the expected value of 0.83 V), (ii) the transmembrane voltage drop was small at high currents (e.g., a voltage drop of 1.1 V up to 1.1 A/cm2), and (iii) the extended bipolar reaction zone for water splitting with interlocking fibers allowed for high current density operation with no evidence of membrane degradation.In this talk, the effect of membrane composition (the type/amount of anion and cation exchange polymers and choice of catalyst) and structure (the thickness of the layers) on short-term and long-term membrane performance will be discussed. Results will be presented for operating the bipolar membrane in water splitting and water generation modes.

Urea-Based Patches with Controlled Release for Potential Atopic Dermatitis Treatment.

Skin diseases such as atopic dermatitis (AD) are widespread and affect people all over the world. Current treatments for dry and itchy skin are mostly focused on pharmaceutical solutions, while supportive therapies such as ointments bring immediate relief. Electrospun membranes are commonly used as a drug delivery system, as they have a high surface to volume area, resulting in high loading capacity. Within this study we present the manufacturing strategies of skin patches using polymer membranes with active substances for treating various skin problems. Here, we manufactured the skin patches using electrospun poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) (PVB) fibers blended and electrosprayed with urea. The highest cumulative release of urea was obtained from the PVB patches manufactured via blend electrospinning with 5% of the urea incorporated in the fiber. The maximum concentration of released urea was acquired after 30 min, which was followed up by 6 h of constant release level. The simultaneous electrospinning and electrospraying limited the urea deposition and resulted in the lowest urea incorporation followed by the low release level. The urea-based patches, manufactured via blend electrospinning, exhibited a great potential as overnight treatment for various skin problems and their development can bring new trends to the textile-based therapies for AD.

Redox-homogeneous, gel electrolyte-embedded high-mass-loading cathodes for high-energy lithium metal batteries

Lithium metal batteries have higher theoretical energy than their Li-ion counterparts, where graphite is used at the anode. However, one of the main stumbling blocks in developing practical Li metal batteries is the lack of cathodes with high-mass-loading capable of delivering highly reversible redox reactions. To overcome this issue, here we report an electrode structure that incorporates a UV-cured non-aqueous gel electrolyte and a cathode where the LiNi0.8Co0.1Mn0.1O2 active material is contained in an electron-conductive matrix produced via simultaneous electrospinning and electrospraying. This peculiar structure prevents the solvent-drying-triggered non-uniform distribution of electrode components and shortens the time for cell aging while improving the overall redox homogeneity. Moreover, the electron-conductive matrix eliminates the use of the metal current collector. When a cathode with a mass loading of 60 mg cm−2 is coupled with a 100 µm thick Li metal electrode using additional non-aqueous fluorinated electrolyte solution in lab-scale pouch cell configuration, a specific energy and energy density of 321 Wh kg−1 and 772 Wh L−1 (based on the total mass of the cell), respectively, can be delivered in the initial cycle at 0.1 C (i.e., 1.2 mA cm−2) and 25 °C.

All-Nanofiber Network Structure for Ultrasensitive Piezoresistive Pressure Sensors.

Sensing materials with fiber structures are excellent candidates for the fabrication of flexible pressure sensors due to their large specific surface area and abundant contact points. Here, an ultrathin, flexible piezoresistive pressure sensor that consists of a multilayer nanofiber network structure prepared via a simple electrospinning technique is reported. The ultrathin sensitive layer is composite nanofiber films composed of poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) and polyamide 6 (PEDOT:PSS/PA6) prepared by simultaneous electrospinning. PEDOT:PSS conductive fibers and PA6 elastic fibers are interwoven to form a multilayer network structure that can achieve ultrahigh sensitivity by forming a wealth of contact points during loading. In particular, gold-deposited PA6 fibers as upper and lower flexible electrodes can effectively increase the initial resistance. Due to this special fiber electrode structure, the sensor is able to generate a large electrical signal variability when subjected to a weak external force. The devices with different sensing properties can be obtained by controlling the electrospinning time. The sensor based on the PEDOT:PSS/PA6 nanofiber network has high sensitivity (6554.6 kPa-1 at 0-1.4 kPa), fast response time (53 ms), and wide detection range (0-60 kPa). Significantly, the device maintains ultrahigh sensitivity when cyclically loaded over 10,000 cycles at 5 kPa, which makes it have great prospects for applications in human health monitoring and motion monitoring.

Fabrication of multifunctional mucoadhesive buccal patch for drug delivery applications

Mucoadhesive buccal patch is a promising dosage form for a successful oral drug delivery, which provides unique advantages for various applications such as treatment of periodontal disease and postdental surgery disorders. The aim of this study is to synthesize a novel multifunctional mucoadhesive buccal patch in a multilayer reservoir design for therapeutic applications. The patches were fabricated through simultaneous electrospinning of chitosan/poly(vinylalcohol) (PVA)/ibuprofen and electrospraying of phenylalanine amino acid nanotubes (PhNTs) containing metronidazole into the electrospun mats through a layer-by-layer process. An electrospun poly(caprolactone) (PCL) was used as an impermeable backing layer to protect the mucoadhesive component from tongue movement and drug loss. Buccal patches were characterized using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM) and also evaluated in terms of physicomechanical parameters such as pH, weight, thickness, tensile strength, folding endurance, and mucoadhesive properties. The swelling index of the patches was examined with respect to the PVA/chitosan ratio. The effect of genipin addition to the electrospinning solution was also studied on mucoadhesive and swelling properties. The cell viability of buccal patches was assessed by methylthiazolydiphenyl-tetrazolium bromide test on L929 fibroblast cell line. The patch with an optimal amount of mucoadhesive polymers (PVA/chitosan 80:20) and crosslinking agent (0.05 g) indicated an ideal hemostatic activity along with antibacterial properties against Streptococcus mutans bacteria. The synthesized multifunctional mucoadhesive patch with a novel composition and design has a great potential for oral therapeutic applications.

Breathable Nanogenerators for an On-Plant Self-Powered Sustainable Agriculture System.

Building an intelligent interface between plants and the environment is of paramount importance for real-time monitoring of the health status of plants, especially promising for high agricultural yield. Although the advancement of various sensors allows automated monitoring, developing a sustainable power supply for these electronic devices remains a formidable challenge. Herein, a waterproof and breathable triboelectric nanogenerator (WB-TENG) is designed based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers embedded with fluorinated carbon nanotubes (F-CNT) microspheres, which was realized by simultaneous electrospinning and electrospraying, respectively. Using carbon nanotubes (CNT) as the electrode, the WB-TENG shows micro-to-nano hierarchical porous structures and high electrostatic adhesion, exhibiting a high output power density of 330.6 μW cm-2, breathability, and hydrophobicity. Besides, the WB-TENG can be conformally self-attached to plant leaves without sacrificing the intrinsic physiological activities of plants, capable of harvesting typical environmental energy from wind and raindrops. Results demonstrate that the WB-TENG can serve as a sustainable power supply for a wireless plant sensor, enabling real-time monitoring of the health status of plants. This work realizes the concept of constructing a plant compatible TENG with environment adaptivity and energy scavenging ability, showing great potential in building a self-powered agriculture system.

Simultaneous Electrospinning and Electrospraying for the Preparation of a Precursor Membrane Containing Hydrothermally Generated Biochar Particles to Produce the Value-Added Product of Carbon Nanofibrous Felt.

Biochar is a byproduct generated from the hydrothermal liquefaction of biomass, such as corn stover, in an anaerobic environment. This work aims to convert biochar into a value-added product of carbon nanofibrous felt. First, the biochar-containing precursor membrane was prepared from simultaneous electrospinning and electrospraying. After thermal stabilization in air and carbonization in argon, the obtained precursor membrane was converted into a mechanically flexible and robust carbon nanofibrous felt. Electrochemical results revealed that the biochar-derived carbon nanofibrous felt might be a good candidate as a supercapacitor electrode with a good rate capability and high kinetic performance.

Synthesis and electrochemical characterization of La0.6Sr0.4Co0.2Fe0.8O3–δ / Ce0.9Gd0.1O1.95 co-electrospun nanofiber cathodes for intermediate-temperature solid oxide fuel cells

Synthesis and electrochemical characterization of composite cathodes, formed from a mixture of La0.6Sr0.4Co0.2Fe0.8O3–δ (LSCF) and Ce0.9Gd0.1O1.95 (GDC) nanofibers, is reported. The electrodes are obtained by simultaneous electrospinning of the two precursor solutions, using apparatus equipped with two spinnerets working in parallel. Results of electrochemical testing carried out through electrochemical impedance spectroscopy (EIS) are presented and discussed. The results suggest that the electrochemical reaction takes place in an electrode region close to the electrode/current collector interface and that the oxygen ions then flow along the ionic conducting path of the GDC fibers. At 650 °C, the polarization resistance is Rp = 5.6 Ω cm−2, in line with literature values reported for other IT-SOFC cathodes.

Mechanically interlocked stretchable nanofibers for multifunctional wearable triboelectric nanogenerator

Abstract Nanofibers with good softness and high surface specific area are excellent choices for wearable triboelectric nanogenerator (TENG), despite that the deformability and durability remain challenging in seamless integration with daily textiles/clothes. Herein, we propose a physical interlocking strategy to realize a self-interlocked stretchable, breathable and waterproof nanofibers-membrane by simultaneous electrospinning of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and electrospraying of styrene-ethylene-butylene-styrene (SEBS). The electrosprayed SEBS microspheres serve as the elastic binders and hydrophobic modifiers for enhancing stretchability and waterproofness of the electrospun PVDF-HFP fibers network. By means of a printable electrode consisted of liquid metal (gallium indium tin particles) and silver flakes, a stretchable nanofibers-based TENG (SNF-TENG) with high triboelectric output (85 V, 219.66 mW m−2) and electrical durability was demonstrated, capable of harvesting energy from human motions and flowing water, powering 200 commercial LEDs and an electronic watch. The stretchable nanofibers membrane shows favorable mechanical compliance, which can be facilely integrated onto stretchable textile to fabricate textile-TENG, promising for comfortable wearable applications for power sources, smart raincoat, self-powered e-skin and tactile interactive interfaces.

Electrospun Eco-Friendly Materials Based on Poly(3-hydroxybutyrate) (PHB) and TiO2 with Antifungal Activity Prospective for Esca Treatment.

Esca is a type of grapevine trunk disease that severely affects vine yield and longevity. Phaeomoniella chlamydospora (P. chlamydospora) is one of the main fungi associated with esca. The aim of the present study was to obtain eco-friendly materials with potential antifungal activity against P. chlamydospora based on biodegradable and biocompatible poly(3-hydroxybutyrate) (PHB), nanosized TiO2-anatase (nanoTiO2), and chitosan oligomers (COS) by conjunction of electrospinning and electrospraying. One-pot electrospinning of a suspension of nanosized TiO2 nanoparticles in PHB solution resulted in materials in which TiO2 was incorporated within the fibers (design type “in”). Simultaneous electrospinning of PHB solution and electrospraying of the dispersion of nanosized TiO2 in COS solution enabled the preparation of materials consisting of PHB fibers on which TiO2 was deposited on the fibers’ surface (design type “on”). Several methods including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), thermogravimetric analyses (TGA) and water contact angle were utilized to characterize the obtained materials. The incorporation of nanoTiO2 in the PHB fibers, as well as nanoTiO2 deposition onto the surface of the PHB fibers resulted in increased roughness and hydrophobicity of the obtained composite fibrous materials. Moreover, TiO2-on-PHB fibrous material exhibited complete inhibition of fungal growth of P. chlamydospora. Therefore, the obtained eco-friendly fibrous materials based on PHB and nanoTiO2 are promising candidates for protection against esca in agriculture.

Direct incorporation of mesenchymal stem cells into a Nanofiber scaffold \u2013 in vitro and in vivo analysis

Bony defects are a common problem in musculoskeletal surgery. Replacement with autologous bone grafts is limited by availability of transplant material. Sterilized cancellous bone, while being osteoconductive, has limited osteoinductivity. Nanofiber scaffolds are currently used for several purposes due to their capability of imitating the extracellular matrix. Furthermore, they allow modification to provide functional properties. Previously we showed that electrospun nanofiber scaffolds can be used for bone tissue regeneration. While aiming to use the osteoinductive capacities of collagen type-I nanofibers we saw reduced scaffold pore sizes that limited cellular migration and thus colonization of the scaffolds. Aim of the present study was the incorporation of mesenchymal stem cells into the electrospinning process of a nanofiber scaffold to produce cell-seeded nanofiber scaffolds for bone replacement. After construction of a suitable spinning apparatus for simultaneous electrospinning and spraying with independently controllable spinning and spraying devices and extensive optimization of the spinning process, in vitro and in vivo evaluation of the resulting scaffolds was conducted. Stem cells isolated from rat femora were incorporated into PLLA (poly-l-lactide acid) and PLLA-collagen type-I nanofiber scaffolds (PLLA Col I Blend) via simultaneous electrospinning and –spraying. Metabolic activity, proliferation and osteoblastic differentiation were assessed in vitro. For in vivo evaluation scaffolds were implanted into critical size defects of the rat scull. After 4 weeks, animals were sacrificed and bone healing was analyzed using CT-scans, histological, immunhistochemical and fluorescence evaluation. Successful integration of mesenchymal stem cells into the scaffolds was achieved by iteration of spinning and spraying conditions regarding polymer solvent, spinning distance, the use of a liquid counter-electrode, electrode voltage and spinning duration. In vivo formation of bone tissue was achieved. Using a PLLA scaffold, comparable results for the cell-free and cell-seeded scaffolds were found, while the cell-seeded PLLA-collagen scaffolds showed significantly better bone formation when compared to the cell-free PLLA-collagen scaffolds. These results provide support for the future use of cell-seeded nanofiber scaffolds for large bony defects.

Tailored PCL Scaffolds as Skin Substitutes Using Sacrificial PVP Fibers and Collagen/Chitosan Blends.

Electrospinning is a versatile technique for fabrication of made-on-purpose biomimetic scaffolds. In this study, optimized electrospun fibrous membranes were produced by simultaneous electrospinning of polycaprolactone (PCL) and polyvinylpyrrolidone (PVP), followed by the selective removal of PVP from the PCL/PVP mesh. After aminolysis, a blend of collagen/chitosan was grafted on the surface. Physicochemical characterizations as well as in vitro evaluations were conducted using different methods. Successful cell infiltration into samples was observed. It seems that the positive trend of cell ingress originates from the proper pore size obtained after removal of pvp (from 4.46 μm before immersion in water to 33.55 μm after immersion in water for 24 h). Furthermore, grafting the surface with the collagen/chitosan blend rendered the scaffolds more biocompatible with improved attachment and spreading of keratinocyte cell lines (HaCaT). Viability evaluation through MTT assay for HDF cells did not reveal any cytotoxic effects. Antibacterial assay with Staphylococcus aureus as Gram-positive and Escherichia coli as Gram-negative species corroborated the bactericidal effects of chitosan utilized in the composition of the coated blend. The results of in vitro studies along with physicochemical characterizations reflect the great potentials of the produced samples as scaffolds for application in skin tissue engineering.

Electrospun PMIA and PVDF-HFP composite nanofibrous membranes with two different structures for improved lithium-ion battery separators

In this study, two methods were used to combine poly (m-phenylene isophthalamide) (PMIA) with polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). The first PMIA@PVDF-HFP consisted of coaxial electrospinning and the second PMIA/PVDF-HFP was based on simultaneous electrospinning using two solutions. The morphology, mechanical and thermal properties, ionic conductivity and electrochemical stability of the as-obtained composite membranes were all investigated. Compared to properties of commercial Celgard membrane, the composite membranes PMIA@PVDF-HFP and PMIA/PVDF-HFP effectively combined the advantages of separate PMIA and PVDF-HFP. They exhibited not only excellent thermal stability and mechanical strength but also outstanding electrochemical stability and battery cycle performance. Moreover, PMIA@PVDF-HFP composite nanofibrous membrane with core (PMIA)-shell (PVDF-HFP) structure showed superior properties than PMIA/PVDF-HFP membrane prepared by simultaneous electrospinning. Hence, it could be used as ideal separator material in lithium-ion batteries.

Fabrication of a PAN–PA6/PANI membrane using dual spinneret electrospinning followed byin situpolymerization for separation of oil-in-water emulsions

A polyacrylonitrile–polyamide 6/polyaniline (PAN–PA6/PANI) doped membrane was prepared using dual spinneret simultaneous electrospinning of PAN and PA6 andin situpolymerization of aniline at low temperature.

Fabrication of perfect CMCS/PVA nanofibers for keeping food fresh via an in situ mixing electrospinning

Electrospun nanofibers are of great significance to many applications. Herein, we report a method to produce carboxymethyl chitosan/ poly (vinyl acetate) (CMCS/PVA) nanofiber webs directly and smoothly by an in situ mixing electrospinning which allows for the simultaneous electrospinning of solutions immediately after mixing. The goal of this study is to facilitate the electrospinning process of CMCS/polymer composites at a high ratio of CMCS and discover their applications in fruit fresh-keeping. The results prove that the electrospun nanofiber webs of CMCS/PVA at the flow rate of 1.6/0.2 ml h−1 can be fabricated smoothly. Moreover, these webs have shown great potential in keeping the bananas’ core fresh owing to their antibacterial activity, breathability, edible, and non-poisonous. We believe this work can be served as a good reference for generating CMCS/polymer composites fiber webs smoothly.

Biomimetic hybrid scaffold consisting of co-electrospun collagen and PLLCL for 3D cell culture

Electrospun collagen is commonly used as a scaffold in tissue engineering applications since it mimics the content and morphology of native extracellular matrix (ECM) well. This report describes “toxic solvent free” fabrication of electrospun hybrid scaffold consisting of Collagen (Col) and Poly(l-lactide-co-ε-caprolactone) (PLLCL) for three-dimensional (3D) cell culture. Biomimetic hybrid scaffold was fabricated via co-spinning approach where simultaneous electrospinning of PLLCL and Collagen was mediated by polymer sacrificing agent Polyvinylpyrrolidone (PVP). Acidified aqueous solution of PVP was used to solubilize collagen without using toxic solvents for electrospinning, and then PVP was readily removed by rinsing in water. Mechanical characterizations, protein adsorption, as well as biodegradation analysis have been conducted to investigate feasibility of biomimetic hybrid scaffold for 3D cell culture applications. Electrospun biomimetic hybrid scaffold, which has 3D-network structure with 300–450 nm fiber diameters, was found to be maximizing cell adhesion through assisting NIH 3T3 mouse fibroblast cells. 3D cell culture studies confirmed that presence of collagen in biomimetic hybrid scaffold have created a major impact on cell proliferation compared to conventional 2D systems on long-term, also cell viability increased with the increasing amount of collagen.

Development of Highly pH-Sensitive Hybrid Membranes by Simultaneous Electrospinning of Amphiphilic Nanofibers Reinforced with Graphene Oxide.

Nanofibrous-based pH sensors have shown promise in a wide range of industrial and medical applications due to their fast response time and good mechanical properties. In the present study, we fabricated pH-sensitive sensors of nanofibrous membranes by electrospinning polyurethane (PU)/poly 2-acrylamido-2-methylpropanesulfonic acid (PAMPS)/graphene oxide (GO) with indicator dyes. The morphology of the electrospun nanofibers was examined using scanning electron microscopy (SEM). The effect of hydrophilic polymer ratio and concentration of GO on the sensing response time was investigated. The sensitivity of the membranes was studied over a wide pH range (1–8) in solution tests, with color change measured by calculating total color difference using UV-vis spectroscopy. The membranes were also subjected to vapor tests at three different pH values (1, 4, 8). SEM results show the successful fabrication of bimodal fiber diameter distributions of PU (mean fiber diameter 519 nm) and PAMPS (mean fiber diameter 78 nm). Sensing response time decreased dramatically with increasing concentrations of PAMPS and GO. The hybrid hydrophobic/hydrophilic/GO nanofibrous membranes are capable of instantly responding to changes in solution pH as well as detecting pH changes in chemical vapor solution in as little as 7 s.