Electrospun Nanofibers Research Articles

Local Delivery of Dual Stem Cell-Derived Exosomes Using an Electrospun Nanofibrous Platform for the Treatment of Traumatic Brain Injury.

Traumatic brain injury poses serious physical, psychosocial, and economic threats. Although systemic administration of stem cell-derived exosomes has recently been proven to be a promising modality for traumatic brain injury treatment, they come with distinct drawbacks. Luckily, various biomaterials have been developed to assist local delivery of exosomes to improve the targeting of organs, minimize nonspecific accumulation in vital organs, and ensure the protection and release of exosomes. In this study, we developed an electrospun nanofibrous scaffold to provide sustained delivery of dual exosomes derived from mesenchymal stem cells and neural stem cells for traumatic brain injury treatment. The electrospun nanofibrous scaffold employed a functionalized layer of polydopamine on electrospun poly(ε-caprolactone) nanofibers, thereby enhancing the efficient incorporation of exosomes through a synergistic interplay of adhesive forces, hydrogen bonding, and electrostatic interactions. First, the mesenchymal stem cell-derived exosomes and the neural stem cell-derived exosomes were found to modulate microglial polarization toward M2 phenotype, play an important role in the modulation of inflammatory responses, and augment axonal outgrowth and neural repair in PC12 cells. Second, the nanofibrous scaffold loaded with dual stem cell-derived exosomes (Duo-Exo@NF) accelerated functional recovery in a murine traumatic brain injury model, as it mitigated the presence of reactive astrocytes and microglia while elevating the levels of growth associated protein-43 and doublecortin. Additionally, multiomics analysis provided mechanistic insights into how dual stem cell-derived exosomes exerted its therapeutic effects. These findings collectively suggest that our novel Duo-Exo@NF system could function as an effective treatment modality for traumatic brain injury using sustained local delivery of dual exosomes from stem cells.

Folic acid in carboxymethylcellulose/polyethylene oxide electrospun nanofibers: preparation, release and stability.

Folic acid (FA), a synthetically produced compound analogous to vitamin B9, also referred to as vitamin folate, is an essential compound in human health and faces challenges in stability during food processing. This study explores the incorporation of FA into carboxymethylcellulose (CMC) nanofibers using electrospinning to enhance its stability. In this study, optimization of both electrospinning and solution parameters facilitated the fabrication of nanofibers. Furthermore, incorporating FA into CMC/polyethylene oxide (PEO) nanofibers resulted in thinner fibers, with an average diameter of 88 nm, characterized by a flat shape and smooth surface. Fourier transform infrared spectroscopic analysis demonstrated substantial hydrogen bonding interactions between FA and the polar groups present in CMC. This interaction contributed to an encapsulation efficiency of 94.5%, with a yield exceeding 87%. Thermal analysis highlighted mutual interference between CMC and PEO, with FA enhancing the thermal stability and reducing the melting temperatures and enthalpies of PEO, while also increasing the reaction heats of CMC. The encapsulated FA remained stable in acidic conditions, with only 6% degradation over 30 days, demonstrating the efficacy of CMC/PEO nanofibers in safeguarding FA against acidic environments. Moreover, the nanofibers provided a protective barrier against UV radiation, thereby preserving the stability of FA. This study emphasizes the efficacy of CMC/PEO nanofibers as a protective matrix against FA degradation. The findings indicate that this innovative approach could significantly diversify the applications of FA in food fortification, addressing concerns regarding its vulnerability to temperature and hydrolysis reactions during food processing. © 2024 Society of Chemical Industry.

High-Performance Self-Cleaning Triboelectric Mini Humidity Sensor Enabled by Facet Engineered Titania Nanocrystals Adorned Nylon-6,6 Electrospun Nanofibers

High-Performance Self-Cleaning Triboelectric Mini Humidity Sensor Enabled by Facet Engineered Titania Nanocrystals Adorned Nylon-6,6 Electrospun Nanofibers

A Piezoelectric Electrospun Nanofiber mat (Kaolin/PVDF) for the Degradation of Methylene Blue in Water

Organic compounds of various classes have been identified as major pollutants commonly detected in several environmental freshwaters. As a potential solution, electrospun mat-like nanofibers comprising polyvinylidene fluoride (PVDF) nanofibers and kaolin clay composite were synthesized for the degradation of methylene blue dye in wastewater using piezocatalytic technique. The kaolin/PVDF composites were characterized with SEM, XRD, FTIR, Chronoamperometry and electrochemical impedance spectroscopy. The poling of the piezoelectric charges of the electrospun mat-like nanofibers, enhanced by the presence of the crystalline nature of the kaolin clay occasioned the generation of reactive species upon exposure to ultrasonic vibration. Moreover, ultrasound waves in the system prevented passivation of the mat’s active surface during piezocatalysis through continuous cleaning action. A degradation efficiency of 100% was obtained from the degradation of methylene blue dye using the synthesized kaolin/PVDF composites during piezocatalysis. This result positions the nanofiber as an effective catalyst in wastewater treatment applications.Graphical

Effect of Electrospun Nanofibrous Film on Drilling-Force Reduction for Fine-Hole Drilling in Metals

Effect of Electrospun Nanofibrous Film on Drilling-Force Reduction for Fine-Hole Drilling in Metals

Cryomilled electrospun nanofiber mats containing d-mannitol exhibit suitable for aerosol delivery of proteins

Dry powder inhalers (DPIs) are the first choice for inhalation drug development. However, some conventional DPI formulation processes require heating, which may damage high molecular weight drugs such as proteins and nucleic acids. In this study, we propose a novel DPI preparation process that avoids the use of heat. Dry powders were prepared by cryomilling nanofiber mats composed of polyvinyl alcohol, D(−)-mannitol (Man), and α-chymotrypsin (α-Chy) as the model drug using the electrospinning method. The addition of Man conferred high dispersibility and excellent in vitro aerosol performance to the nanofiber mat powder in a very short milling time (less than 0.5 min) as assessed using the Andersen cascade impactor. Powders were classified according to the degree of friability, and among these, nanofiber mats containing 15 % Man and milled for 0.25 min exhibited the highest aerosol performance. Nanofiber mats containing Man milled for less than 0.5 min also exhibited greater α-Chy enzymatic activity than a nebulized α-Chy solution. Furthermore, single inhalation induced no significant lung tissue damage as evidenced by lactate dehydrogenase activity assays of mouse bronchoalveolar lavage fluid. This novel DPI formulation process may facilitate the safe and efficient inhalational delivery of therapeutic proteins.

Correction: Physico-mechanical Evaluation of Electrospun Nanofibrous Mats of Poly(3-hydroxybutyrate)/Poly(butylene succinate) Blends with Enhanced Swelling-Dynamics and Hydrolytic Degradation-Kinetics Stability for Pliable Scaffold Substrates

Correction: Physico-mechanical Evaluation of Electrospun Nanofibrous Mats of Poly(3-hydroxybutyrate)/Poly(butylene succinate) Blends with Enhanced Swelling-Dynamics and Hydrolytic Degradation-Kinetics Stability for Pliable Scaffold Substrates

Alginate-Based Electrospun Nanofibers and the Enabled Drug Controlled Release Profiles: A Review.

Alginate is a natural polymer with good biocompatible properties and is a potential polymeric material for the sustainable development and replacement of petroleum derivatives. However, the non-spinnability of pure alginate solutions has hindered the expansion of alginate applications. With the continuous development of electrospinning technology, synthetic polymers, such as PEO and PVA, are used as co-spinning agents to increase the spinnability of alginate. Moreover, the coaxial, parallel Janus, tertiary and other diverse and novel electrospun fiber structures prepared by multi-fluid electrospinning have found a new breakthrough for the problem of poor spinning of natural polymers. Meanwhile, the diverse electrospun fiber structures effectively achieve multiple release modes of drugs. The powerful combination of alginate and electrostatic spinning is widely used in many biomedical fields, such as tissue engineering, regenerative engineering, bioscaffolds, and drug delivery, and the research fever continues to climb. This is particularly true for the controlled delivery aspect of drugs. This review provides a brief overview of alginate, introduces new advances in electrostatic spinning, and highlights the research progress of alginate-based electrospun nanofibers in achieving various controlled release modes, such as pulsed release, sustained release, biphasic release, responsive release, and targeted release.

Nanofibers loaded levosalbutamol sulfate fast dissolving oral films for sublingual delivery

During allergic reactions, a drug should work quickly and effectively. Levosalbutamol (LSAL) is a short-acting drug that stimulates β2 adrenergic receptors and is commonly used to treat asthma and chronic obstructive pulmonary disease (COPD). This study aimed to prepare sublingual oral patches of levosalbutamol sulfate electrospun nanofibers for ultrafast release. In this study, we fabricated nanofibers by electrospinning polyvinyl alcohol (PVA) polymer (10 %) and different concentrations (3, 5, and 10 %) of LSAL. The nanofibers are randomly aligned, with smooth surfaces and an average fiber diameter of 160, 170, and 198 nm at PVA/LSAL concentrations of 3 %, 5 %, and 10 %, respectively. The in vitro dissolution study showed that all PVA/LSAL nanofibers released the drug ultra-fast (within 5–10 min); 90 % released within 3 min. The folding endurance study revealed that the drug-loaded nanofibers had improved stability. A disintegration study showed that the nanofibers disintegrated rapidly in 1–3 min, and an in vitro cytocompatibility study showed good cell viability with A549 human lung cells. Hence, the proposed fast-dissolving sublingual oral films/patches approach is a promising alternative to existing dosage forms. They can provide an ultra-fast release of various drugs requiring a fast onset of action with increased bioavailability and patient compliance.

Fabrication and Characterization of Electrospun Ocimum sanctum and Curcumin-Loaded Nanofiber Membrane for the Management of Periodontal Disease: An In Vitro Study.

Background Periodontal disease is a chronic inflammatory condition that gradually deteriorates the supportive tissues of teeth, eventually leading to tooth loss. Mechanical debridement stands as the gold standard method for treating periodontitis. However, antimicrobial therapy is recommended for optimal results when used alongside mechanical debridement. Numerous studies have investigated local drug delivery as an adjunct to mechanical debridement of affected tooth surfaces. Ocimum sanctum exhibits anti-inflammatory, antioxidant, and antimicrobial properties. Similarly, curcumin, as documented in the literature, demonstrates a broad spectrum of anti-inflammatory and antimicrobial effects. Electrospinning has demonstrated itself to be a highly effective method for fabricating drug-loaded fibers. Electrospun nanofibers containing Ocimum sanctum and curcumin are expected to exhibit greater efficacy due to their increased surface area, facilitating the dispersion of larger quantities of drugs, and their ability to control drug release when employed as a local drug delivery system. This study aims to fabricate and characterize the properties of nanofiber membranes loaded with Ocimum sanctum and curcumin using the electrospinning technique. Methods About 50 mg each of Ocimum sanctum and curcumin were blended with 15% polyvinyl alcohol and 2% chitosan polymer in a 4:1 ratio and left to stir overnight. A 10 mL syringe was filled with this solution, and an 18 G blunt-end needle charged at 15.9 kV was used for extrusion. Continuous fibers were collected onto a collector plate positioned 12 cm from the center of the needle tip, at a flow rate of 0.005 mL/min. The morphology of the fabricated membrane was assessed through scanning electron microscopy (SEM), the strength of the material was assessed through tensile strength analysis using INSTRON, an Electropuls E3000 Universal Testing Machine(INSTRON, Norwood, MA), and the drug release pattern was analyzed using Jasco V-730 UV-visible spectrophotometer(Jasco, Easton, MD). Results The morphology of this nanofiber showed a random distribution of fibers with no bead formation. The average diameter of the membrane was 383±102 nm, and the tensile strength of this material was 1.87 MPa. The drug release pattern showed an initial burst release of Ocimum sanctum, followed by a controlled release in subsequent hours. However, curcumin showed very little drug release because of its solubility. Conclusion In summary, the Ocimum sanctum and curcumin-loaded nanofibers exhibited robust tensile strength, a controlled drug release profile, and uniform drug distribution within the nanofiber membrane. Consequently, it can be concluded that curcumin nanofibers and electrospun Ocimum sanctum serve as valuable agents for local drug delivery in the treatment of periodontitis.

Development of Hybrid Electrospun Nanofibers: Improving Effects of Cellulose Nanofibers (CNFs) on Electrospinnability of Gelatin.

Cellulose nanofibers (CNFs) were used to improve the electrospinnability of the gelatin protein in a water/ethanol/acetic acid (3:2:3, v/v) solution. The effects of different concentrations of CNFs (0.5-4%) on the important physical properties of the gelatin solution (15%), including rheology, conductivity, and surface tension, were investigated. The apparent viscosity and shear-thinning behavior were increased by increasing the CNF concentration from 0 to 4% at a low shear rate (<10 s-1). CNFs also increased the electrical conductivity and surface tension of the gelatin solution. Scanning electron microscopy (SEM) images revealed uniformly ordered structures with good continuity without fracture or bead formation in all hybrid nanofibers. They also showed that the average diameters of fibers decreased from 216 nm in the pure gelatin nanofibers to 175.39 nm in the hybrid gelatin/CNF (4%) ones. Differential scanning calorimetry (DSC) results showed that CNFs increased Tg, and X-ray diffraction (XRD) analysis showed that the electrospinning process caused the formation of more amorphous structures in the gelatin/CNF hybrid nanofibers. The tensile test indicated that by adding 2% CNFs, the ultimate tensile strength (UTS) and strain at break (SB) of nanofiber mats increased from 4.26 to 10.5 MPa and 3.3% to 6.25%, respectively. The current study indicated that incorporating CNFs at the optimal concentration into a gelatin solution can improve the resulting hybrid nanofibers' morphology, average diameter, and mechanical properties.

Electrospun nanofibers-based thin film microextraction for enrichment of phthalate esters in biodegradable plastics.

In this work, a novel electrospun nanofiber (PAN/TpBD; 2,4,6-triformylphloroglucinol [Tp] and benzidine [BD]; polyacrylonitrile [PAN]) was fabricated via a facile electrospinning method and utilized as adsorbent in thin film microextraction (TFME) of phthalate esters (PAEs) (dimethyl phthalate, diethyl phthalate, diallyl phthalate, dibutyl phthalate, and dioctyl phthalate) in biodegradable plastics. The prepared PAN/TpBD combines the strong stability of nanofibers with increased exposure sites for covalent organic frameworks and enhanced interactions with the target, thus improving the enrichment effect on the target. The extraction efficiency of PAN/TpBD reached above 80%. Based on PAN/TpBD, a TFME-high-performance liquid chromatography method was established, and the experimental parameters were optimized. Under the optimal extraction conditions, the PAEs of this method varied linearly in the range of 10-10 000µg/L with low detection limits (0.69-2.72µg/L). The intra-day and inter-day relative standard deviation values of the PAEs were less than 8.04% and 8.73%, respectively. The adsorbent can achieve more than 80% recovery of the five targets after six times reuse. The developed method was successfully applied for the determination of trace PAEs in biodegradable plastics with recoveries ranging from 80.1% to 113.4% and relative standard deviations were less than 9.45%. The as-synthesized PAN/TpBD adsorbent exhibited great potential in PAE analysis.

Correction to [Impact of concentration and aging time of pea starch‐based polymeric solutions on the fabrication of electrospun nanofibers

Correction to [Impact of concentration and aging time of pea starch‐based polymeric solutions on the fabrication of electrospun nanofibers

Electrospun porous polyacrylonitrile/polyvinylpyrrolidone nanofiber membrane with ultra-hydrophilic and high moisture-permeability for dust personal protection

The serious dust pollution in coal mine working environment can cause occupational lung diseases and other diseases, affecting the life and health of miners. Therefore, the prospect of developing an air filtration membrane with high filtration performance is of remarkable significance. This study prepared a porous Polyacrylonitrile (PAN) /Polyvinylpyrrolidone (PVP) nanofiber membrane based on Electrospinning and post-treatment technology used for downhole personal protection. The prepared porous nanofiber membrane increased the specific surface area by 133.63 % and the porosity by 391.02 % (compared with the pure PAN nanofiber membrane), and was able to achieve a high filtration efficiency of 98.76 % and a low pressure drop of 165 Pa at an air flow rate of 85 L/min. Meanwhile, this study conducted contact angle and moisture permeability tests on the prepared composite fiber membrane. After 1 second of water droplets falling on the fiber membrane, it had a 14° contact angle (strong hydrophilicity), and the moisture permeability reached 4256.677 cm3/m2·d·Pa, which could discharge the water vapor generated by respiration in time. In addition, given the complex and irregular pore distribution of electrospun nanofibers, the fractal correlation dimension of nanofiber membrane pores was studied through fractal theory, and the relationship between the fractal dimension of fiber pores and respiratory resistance was discussed. Based on this, the nanofiber membrane prepared in this study can be widely used in individual protection in mines.

NIR-responsive electrospun nanofiber dressing promotes diabetic-infected wound healing with programmed combined temperature-coordinated photothermal therapy

BackgroundDiabetic wounds present significant challenges, specifically in terms of bacterial infection and delayed healing. Therefore, it is crucial to address local bacterial issues and promote accelerated wound healing. In this investigation, we utilized electrospinning to fabricate microgel/nanofiber membranes encapsulating MXene-encapsulated microgels and chitosan/gelatin polymers.ResultsThe film dressing facilitates programmed photothermal therapy (PPT) and mild photothermal therapy (MPTT) under near-infrared (NIR), showcasing swift and extensive antibacterial and biofilm-disrupting capabilities. The PPT effect achieves prompt sterilization within 5 min at 52 °C and disperses mature biofilm within 10 min. Concurrently, by adjusting the NIR power to induce local mild heating (42 °C), the dressing stimulates fibroblast proliferation and migration, significantly enhancing vascularization. Moreover, in vivo experimentation successfully validates the film dressing, underscoring its immense potential in addressing the intricacies of diabetic wounds.ConclusionsThe MXene microgel-loaded nanofiber dressing employs temperature-coordinated photothermal therapy, effectively amalgamating the advantageous features of high-temperature sterilization and low-temperature promotion of wound healing. It exhibits rapid, broad-spectrum antibacterial and biofilm-disrupting capabilities, exceptional biocompatibility, and noteworthy effects on promoting cell proliferation and vascularization. These results affirm the efficacy of our nanofiber dressing, highlighting its significant potential in addressing the challenge of diabetic wounds struggling to heal due to infection.Graphical

Tailoring optical properties and humidity sensing response of multilayered Tb(Sal)3Phen and Eu(DBM)3Phen complex nanofibres

In this work, we investigate the opto-humidity sensing and colour tuning in polyvinyl alcohol (PVA) polymeric electrospun nanofibres dispersed with Tb(Sal)3Phen (TSP) and Eu(DBM)3Phen (EDP) complexes. Fourier transform infrared spectroscopy, scanning electron microscopy, and photoluminescence analysis were used to thoroughly analyse the structural, morphological, and spectroscopic features of the synthesised nanofibres in single and stacked multilayer nanofibres. A spectroscopic analysis was performed on all configuration schemes. Under UV excitations, the synthesised TSP complex and EDP complex inhibited nanofibres yield green and red emission corresponding to 5D4→7Fj (j = 4, 5, 6) and 5D0→7Fj (j = 0, 1, 2, 3) transitions attributed to Tb3+ and Eu3+ ions, respectively. The EDP nanofibres presented better UV radiation absorption than TSP, which was attributed to higher absorptivity of DBM than Sal. Additionally, the photoluminescence intensity ratio of characteristic emission peaks i.e. 544 nm (5D4→7F5)/615 nm (5D0→7F2) is function of humidity exposure and excitation wavelength. The stacked multilayer nanofibres exhibit good response and recovery times, 35 and 52 s, negligible hysteresis, and cyclic stability.

Developing novel multifunctional protective clothes for disabled individuals using bio-based electrospun nanofibrous membranes

A novel kind of protective apparel for handicapped persons has been created with bio-based electrospun nanofibrous (NFs) membranes. Hydrophobic membranes with fine polylactic acid (PLA) NFs had a smooth, bead-less structure with an average diameter of 950 nm. The hydrophilic layer has a similar pattern but a smaller fiber diameter dispersion and an average diameter of 750 nm. The silica nanoparticle-modified super-hydrophobic top layer (contact angle, ~153°) repels water and keeps the user dry. Super-hydrophilic silver nanoparticles in the fabric's bottom layer react with perspiration to kill microorganisms. The fabric's porosity (avg. 1.2–1.5 μm) allows for breathability, while silica nanoparticles boost infrared radiation reflection, keeping users cool on hot days. The dual-layer textile has 4.9 MPa ultimate tensile strength and 68 % elongation compared to the membrane's super-hydrophobic and super-hydrophilic layers. Wearing protective clothes reduced hand temperature by 25 % in direct sunlight and 13 % in a sun simulator with 1 Sun. This fabric will work well for adult diapers, outdoor clothing, and disability accessories. Overall, the protective textiles may improve the quality of life for disabled and elderly people by providing usable textile items adapted to their needs.

Electrospun fibrillary scaffold for electrochemical cell biomarkers detection

A novel scaffold for in situ electrochemical detection of cell biomarkers was developed using electrospun nanofibers and commercial adhesive polymeric membranes. The electrochemical sensing of cell biomarkers requires the cultivation of the cells on/near the (bio)sensor surface in a manner to preserve an appropriate electroactive available surface and to avoid the surface passivation and sensor damage. This can be achieved by employing biocompatible nanofiber meshes that allow the cells to have a normal behavior and do not alter the electrochemical detection. For a better mechanical stability and ease of handling, nylon 6/6 nanofibers were collected on commercial polymeric membranes, at an optimal fiber density, obtaining a double-layered platform. To demonstrate the functionality of the fabricated scaffold, the screening of cellular stress has been achieved integrating melanoma B16-F10 cells and the (bio)sensor components on the transducer whereas the melanin exocytosis was successfully quantified using a commercial electrode. Either directly on the surface of the (bio)sensor or spatially detached from it, the integration of cell cultures in biosensing platforms based on electrospun nanofibers represents a powerful bioanalytical tool able to provide real-time information about the biomarker release, enzyme activity or inhibition, and monitoring of various cellular events.Graphical

Nanofibrous Conductive Sensor for Limonene: One-Step Synthesis via Electrospinning and Molecular Imprinting.

Detecting volatile organic compounds (VOCs) emitted from different plant species and their organs can provide valuable information about plant health and environmental factors that affect them. For example, limonene emission can be a biomarker to monitor plant health and detect stress. Traditional methods for VOC detection encounter challenges, prompting the proposal of novel approaches. In this study, we proposed integrating electrospinning, molecular imprinting, and conductive nanofibers to fabricate limonene sensors. In detail, polyvinylpyrrolidone (PVP) and polyacrylic acid (PAA) served here as fiber and cavity formers, respectively, with multiwalled carbon nanotubes (MWCNT) enhancing conductivity. We developed one-step monolithic molecularly imprinted fibers, where S(-)-limonene was the target molecule, using an electrospinning technique. The functional cavities were fixed using the UV curing method, followed by a target molecule washing. This procedure enabled the creation of recognition sites for limonene within the nanofiber matrix, enhancing sensor performance and streamlining manufacturing. Humidity was crucial for sensor working, with optimal conditions at about 50% RH. The sensors rapidly responded to S(-)-limonene, reaching a plateau within 200 s. Enhancing fiber density improved sensor performance, resulting in a lower limit of detection (LOD) of 137 ppb. However, excessive fiber density decreased accessibility to active sites, thus reducing sensitivity. Remarkably, the thinnest mat on the fibrous sensors created provided the highest selectivity to limonene (Selectivity Index: 72%) compared with other VOCs, such as EtOH (used as a solvent in nanofiber development), aromatic compounds (toluene), and two other monoterpenes (α-pinene and linalool) with similar structures. These findings underscored the potential of the proposed integrated approach for selective VOC detection in applications such as precision agriculture and environmental monitoring.

Characterization Electrospun Nanofibers Based on Cellulose Triacetate Synthesized from Licorice Root Cellulose

Cellulose triacetate (CTA) nanofibers were formed by electrospinning using two binary solvent systems: methylene chloride/ethanol and chloroform/acetone. Previously, licorice root cellulose (LRC) with a degree of polymerization (DP) of 710 was extracted from licorice root waste by alkaline treatment and hydrogen peroxide bleaching at high temperatures. Then CTA with a degree of substitution (DS) of 2.9 and an average molecular weight of 175 kDa was synthesized from LRC using acetic acid and acetic anhydride, sulfuric acid was as a catalyst. The influence of the electrospinning process and various solvent systems on the morphology and structure of nanofibers is studied. The structure and morphology of the nanofibers were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and the sorption characteristics were also investigated. The results showed that the morphology and structure of nanofibers depended on the solvent mixture used. The average diameters of the CTA nanofibers with grooved morphology varied 200-700 nm (solvent methylene chloride/ethanol) and the dumbbell-shaped (flat ribbon) CTA nanofibers in a wide range from 200 nm to 4 mkm (solvent chloroform/acetone).