Electrospinning Setup Research Articles

Unveiling the Mechanism of the in Situ Formation of 3D Fiber Macroassemblies with Controlled Properties.

Electrospinning technique is well-known for the generation of different fibers. While it is a "simple" technique, it lies in the fact that the fibers are typically produced in the form of densely packed two-dimensional (2D) mats with limited thickness, shape, and porosity. The highly demanded three-dimensional (3D) fiber assemblies have been explored by time-consuming postprocessing and/or complex setup modifications. Here, we use a classic electrospinning setup to directly produce 3D fiber macrostructures only by modulating the spinning solution. Increasing solution conductivity modifies electrodynamic jet behavior and fiber assembling process; both are observed in situ using a high-speed camera. More viscous solutions render thicker fibers that own enhanced mechanical stiffness as examined by finite element analysis. We reveal the correlation between the universal solution parameters and the dimensionality of fiber assemblies, thereof, enlightening the design of more "3D spinnable" solutions that are compatible with any commercial electrospinning equipment. After a calcination step, ultralightweight ceramic fiber assemblies are generated. These inexpensive materials can clean up exceptionally large fractions of oil spillages and provide high-performance thermal insulation. This work would drive the development and scale-up production of next-generation 3D fiber materials for engineering, biomedical, and environmental applications.

Aspects of Polymeric-Based Membranes in the Water Treatment Field: An Interim Structural Analysis

Solar-driven interfacial evaporation (SDIE) is considered a sustainable and environmentally friendly technology for using solar energy to produce fresh water, which is a crucial resource for the existence of human life. Porous membranes are widely used in SDIE owing to their porous structure, which is highly suitable for this kind of photothermal material and allows an efficient supply of water and escape of vapor during the evaporation process. Electrospinning is perhaps the most versatile technique to produce highly porous structures of nanofiber membranes with a large surface-to-volume ratio, high porosity, low density, and many advantages. Nevertheless, acquiring a stronger background on the initial research questions in this enticing field of research needs further investigation. Typically, for the enhancement of process control, the impact of flow rate on the morphology of the prepared membrane is quite important. This research article has two-fold objectives: firstly, it discusses the fundamental description of the photothermal conversion mechanism of polymer-based photothermal materials for water treatment. A systematic investigation supported by previous studies revealing the working mechanism and the design of solar-driven interfacial evaporation has been provided. On the other hand, our interim experimental results elaborate on the influence of process conditions such as electrospinning parameters on the structural morphology and diameter of fabricated electrospun nanofibers produced by using the coaxial electrospinning setup in our lab. The scanning electron microscope (SEM) was used to examine the morphology of the electrospun nanofibers. Our introductory results provide a useful insight into tuning the necessary process parameters to fabricate electrospun polyacrylonitrile (PAN) nanofiber membranes by electrospinning technique. From our preliminary results after the three processing experiments, it is revealed that a polymer concentration of 10% wt., an applied voltage of 20 kV, a tip-to-collector distance of 18 cm, and a flow rate of 0.8 mL/h produce the optimum nanofiber membranes with a uniform structure and a diameter in the range 304–394 nm. The variation in the diameter of nanofibers in the three processing conditions is endowed by the regulation of the initiating droplet extruded from the tip of the metallic needle (syringe jet) to the collector using the electrospinning setup.

Gas-assisted electrospinning of high-performance ceramic fibers: Optimal design modelling and experimental results of the gas channel of the nozzle

Electrospinning (ES) of ceramic fibers has mostly remained in the research level, which can be because of the hard process and parameters controlling the low rate of production. The yield of fiber production by solution blow spinning (SBS) is exciting but the production process is unstable due to the reverse flow phenomenon. In this paper, we prepared high-performance ceramic fibers by gas-assisted electrospinning (GES), which combined the advantages of ES and SBS. Also, comprehensive numerical and experimental analysis for nanofibers produced using GES are provided. The gas flow characteristics through different parameters' nozzle were investigated numerically using computational fluid dynamics and experimentally in a custom-built gas-assisted electrospinning setup to produce SiO2 nanofibers.

Effects of pectin-calcium matrices on controlling in vitro digestion of normal maize starch

Normal maize starch was encapsulated with different (low-methoxyl) pectin concentrations (2–7%, w/v) using the ionic gelation method. The mixtures were ejected into the crosslinking agent (5%, w/v calcium chloride solution) by an electrospinning apparatus. In order to study the effects of pectin-calcium matrices on starch digestion, the particle size distribution, thermal properties, and in vitro starch digestion kinetics of the encapsulated sample were consequently studied. The results showed that the encapsulation successfully diminished starch amylolysis, indicated by the reduction of digested starch and the apparent digestion rate coefficient. The highest pectin concentration (7%, w/v) caused the greater network formation, which contributed to the greatest particle size distribution and highest gelatinization temperature but caused the lowest starch hydrolysis (p < 0.05). This study found that pectin-calcium matrix development is a crucial key in controlling starch hydrolysis since the network provides a complex structure and reduces the surface areas of starch granules that are available to the digestive enzyme.

Collagen Nanoyarns: Hierarchical Three-Dimensional Biomaterial Constructs.

Hierarchical fibrous scaffolds (HFS) consist of nanoscale fibers arranged in larger macroscale structures, much in the same pattern as in native tissue such as tendon and bone. Creation of continuous macroscale nanofiber yarns has been made possible using modified electrospinning set-ups that combine electrospinning with techniques such as twisting, drawing, and winding. In this paper, a modified electrospinning setup was used to create continuous yarns of twisted type I collagen nanofibers, also known as collagen nanoyarns (CNY), from collagen solution prepared in acetic acid. Fabricated CNYs were cross-linked and characterized using SEM imaging and mechanical testing, while denaturation of collagen and dissolution of the scaffolds were assessed using circular dichroism (CD) and UV-vis spectroscopy, respectively. HeLa cells were then cultured on the nanoyarns for 24 h to assess cell adhesion on the scaffolds. Scanning electron micrographs revealed a twisted nanofiber morphology with an average nanofiber diameter of 213 ± 60 nm and a yarn diameter of 372 ± 23 μm that shrank by 35% after covalent cross-linking. Structural denaturation assessment of native collagen using circular dichroism (CD) spectroscopy showed that 60% of the triple-helical collagen content in CNYs was retained. Cross-linking of CNYs significantly improved their mechanical properties as well as stability in buffered saline with no sign of degradation for 14 days. In addition, CNY strength and stiffness increased significantly with cross-linking although in the wet state, significant loss in these properties, with a corresponding increase in elasticity, was observed. HeLa cells cultured on cross-linked CNYs for 24 h adhered to the yarn surface and oriented along the nanofiber alignment axis, displaying the characteristic spindle-like morphology of cells grown on surfaces with aligned topography. Collectively, the results demonstrate the promising potential of collagen nanoyarns as a new class of shapable biomaterial scaffold and building block for generating macroscale fiber-based tissues.

Near‐infrared light activated core‐shell electrospun nanofibers decorated with photoactive plasmonic nanoparticles for on‐demand smart drug delivery applications

AbstractOver the last few years, traditional drug delivery systems (DDSs) have been transformed into smart DDSs. Recent advancements in biomedical nanotechnology resulted in introducing stimuli‐responsiveness to drug vehicles. Nanoplatforms can enhance drug release efficacy while reducing the side effects of drugs by taking advantage of the responses to specific internal or external stimuli. In this study, we developed an electrospun nanofibrous photo‐responsive DDSs. The photo‐responsivity of the platform enables on‐demand elevated drug release. Furthermore, it can provide a sustained release profile and prevent burst release and high concentrations of drugs. A coaxial electrospinning setup paired with an electrospraying technique is used to fabricate core‐shell PVA‐PLGA nanofibers decorated with plasmonic nanoparticles. The fabricated nanofibers have a hydrophilic PVA and Rhodamine‐B (RhB) core, while the shell is hydrophobic PLGA decorated with gold nanorods (Au NRs). The presence of plasmonic nanoparticles enables the platform to twice the amount of drug release besides exhibiting a long‐term release. Investigations into the photo‐responsive release mechanism demonstrate the system's potential as a “smart” drug delivery platform.

Electrospinning spinneret: A bridge between the visible world and the invisible nanostructures

Electrospinning spinneret: A bridge between the visible world and the invisible nanostructures

FABRICATION AND CHARACTERIZATION OF ELECTROSPUN ANTHOCYANIN-LOADED POLYLACTIDE NANOFIBERS

In this study, morphological, chemical and thermal characteristics of biobased and biodegradable anthocyanin-loaded polylactide (PLA) nanofibrous membranes were investigated. To prepare electrospinning solutions, PLA was dissolved at a concentration of 10% (wv-1) in a solvent system of chloroform/dimethylformamide (75/25% vv-1), and anthocyanin at different concentrations (1, 2, and 3% wv−1) was added into the polymer solutions. The prepared solutions were electrospun by using a single syringe electrospinning setup. The morphological, chemical and thermal structure of the neat and anthocyanin-loaded PLA nanofibrous membranes were characterized via Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Differential Scanning Calorimetry (DSC), respectively. The FT-IR spectra proved the incorporation of anthocyanin into nanofibrous membranes successfully. It was observed that when anthocyanin was added into the polymer solution; bead-free nanofibers were produced, and when the concentration of anthocyanin was increased, mean fiber diameter increased as well. In addition, anthocyanin loading did not affect the crystallization behavior of PLA; however, the glass transition temperature (Tg) of the nanofibrous membranes including no anthocyanin in the structure was higher than those of the other membranes including anthocyanin.

Electrospun Nanofiber: Application in Tissue Regeneration

Abstract: An injury to the human body is classified as a wound if it results in a cut or a break in the skin. Depending on the depth of the skin layer, a wound can either be limited to the epidermal layer, which heals via re-epithelialization without the need for skin grafts, or full-thickness wounds, which result in the loss of both the epidermis and dermis (FTW). A full-thickness wound cannot heal on its own and needs a skin graft or tissue regeneration product to heal quickly. This paper provides a comprehensive overview of the properties of electrospun nanofibers and their application as skin regeneration products rapid healing of the full-thickness wound. The paper first introduces the skin, its layers, and various problems associated with human skin. In the next part, a wound is discussed in terms of acute and chronic wounds. Primary, secondary and tertiary clinical wound healing has also been discussed. The next part briefly introduces the four different phases of healing, i.e. hemostasis, inflammation, proliferative and maturation of newly deposited collagen into tissues. The effect of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) on reactive oxygen species, reactive nitrogen species and reactive sulphur species, and their effect on healing time was discussed. The electrospinning process's evolution and setup, properties of electrospun nanofibers, a component of electrospinning solution, and various parameters affecting electrospinning were discussed. Application on nanofiber scaffold in terms of drug delivery and tissue regeneration was highlighted. In the end, improvement in the existing nanofibrous scaffold was briefly highlighted.

Nanofiber-in-microfiber carbon/silicon composite anode with high silicon content for lithium-ion batteries

Silicon-rich anodes are desired to leverage the energy capacity of lithium-ion batteries (LIBs) towards critical markets. We prepared new silicon-rich composite anodes with a nanofiber-in-microfiber architecture using a co-axial electrospinning setup. A polyvinyl alcohol (PVA) solution that allows high silicon content serves as the central stream, which holds silicon nanoparticles into short, branched composite nanofibers. These nanofibers were wrapped by long, ductile microfibers made of polyacrylonitrile (PAN) that is supplied in the sheath fluid. After carbonization, the received carbon/silicon composites were tested as the anode of LIBs, in which the silicon-rich nanofibers host the majority of lithium ions while their thin carbon skin originated from PVA promotes the conductivity and charge transfer. The outside PAN-derived microfibers provide needed structural support for those encapsulated silicon-rich nanofibers, making the final composites also an integrated, three-dimensional current collector. The nanofibrous morphology and the void space in between help accommodate the notorious volume expansion issues during lithiation/delithiation. The new composites were confirmed on their nanofiber-in-microfiber configuration. With a Si content of 40%, this unique fibrous anode material achieves ∼900 mAh g−1 specific capacity and ∼90% capacity retention from cycle 50 to cycle 250 by effectively balancing some major challenges associated with silicon-rich anodes.

Electrospinning with Droplet Generators: A Method for Continuous Electrospinning of Emulsion Fibers

Emulsion electrospinning is a promising method for creating fibrous vehicles for delivery of drugs and bioactive compounds for the medical and food industries. Droplet microfluidics is a potent way of continuously generating controllable emulsion droplets. The incorporation of a droplet generator in an electrospinning setup for continuous electrospinning of emulsion fibers has been investigated. The influence of a droplet generator on the morphology of emulsion fibers has been established through electrospinning of emulsions of grapeseed oil in PVA and gelatine. The droplet generator was found to have no influence on the morphology of fibers. Conventional emulsification methods and droplet generator emulsification has been used to investigate the influence of emulsion droplet sizes on the morphology of emulsion fibers. Increasing the emulsion droplet size was found to create in-fiber droplets with diameters larger than the fiber diameter. The size of the in-fiber droplets was found to be dependent on both material and emulsion size.

미세섬유 기반의 생체적합성 관구조에 대한 기계적 물성 조절에 관한 연구

There are various conduit structures such as arteries, veins, and airways in the human body, and they play critical roles in each tissue/organ. However, in recent years, the demand for artificial substitutes for the damaged conduit structure-based tissues and organs has significantly increased as dietary life has rapidly changed. Accordingly, various studies have been conducted, to develop a conduit structure of biocompatible polymers. In this study a 5 mm-diameter conduit structure was developed, using electrospinning process. An electrospinning setup equipped with a cylindrical-rod collector was constructed to fabricate a fibrous conduit structure, and then the impacts of process conditions on morphological and mechanical properties were investigated. Finally, it was shown that the mechanical properties of the fibrous conduit structure in circumferential direction, can be controlled by the electrospinning process conditions.

Optimal delivery of poorly soluble drugs using electrospun nanofiber technology: Challenges, state of the art, and future directions.

Poor aqueous solubility of both, existing drug molecules and those which are currently in the developmental stage, have posed a great challenge to pharmaceutical scientists because they often exhibit poor dissolution behavior and subsequent poor and erratic bioavailability. This has triggered extensive research to explore nanotechnology-based technology platforms for possible rescue. Recently, nanofibers have been exploited widely for diverse biomedical applications including for drug delivery. Electrospun nanofibers are capable of preserving the homogeneously loaded therapeutic agents in amorphous state potentialy impairing devitrification. The present review aims at providing an overview of the various key factors that affect the electrospinning process and characteristics of the nanofibers while fabrication of drug loaded nanofibers for poorly soluble drug candidates. The review explores various methodological advancements in the electrospinning process and set-ups for production scale-up. The various types of electrospun nanofibers (like simple matrix, core-sheath, Janus, and inclusion complex nanofibers) that have been exploited for the delivery of poorly soluble drugs are also critically assessed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Self-Searching Writing of Human-Organ-Scale Three-Dimensional Topographic Scaffolds with Shape Memory by Silkworm-like Electrospun Autopilot Jet.

Bioengineered scaffolds satisfying both the physiological and anatomical considerations could potentially repair partially damaged tissues to whole organs. Although three-dimensional (3D) printing has become a popular approach in making 3D topographic scaffolds, electrospinning stands out from all other techniques for fabricating extracellular matrix mimicking fibrous scaffolds. However, its complex charge-influenced jet–field interactions and the associated random motion were hardly overcome for almost a century, thus preventing it from being a viable technique for 3D topographic scaffold construction. Herein, we constructed, for the first time, geometrically challenging 3D fibrous scaffolds using biodegradable poly(ε-caprolactone), mimicking human-organ-scale face, female breast, nipple, and vascular graft, with exceptional shape memory and free-standing features by a novel field self-searching process of autopilot polymer jet, essentially resembling the silkworm-like cocoon spinning. With a simple electrospinning setup and innovative writing strategies supported by simulation, we successfully overcame the intricate jet–field interactions while preserving high-fidelity template topographies, via excellent target recognition, with pattern features ranging from 100’s μm to 10’s cm. A 3D cell culture study ensured the anatomical compatibility of the so-made 3D scaffolds. Our approach brings the century-old electrospinning to the new list of viable 3D scaffold constructing techniques, which goes beyond applications in tissue engineering.

The Construction of Biologically Relevant Fiber-Reinforced Hydrogel Geometries Using Air-Assisted Dual-Polarity Electrospinning.

Fiber-reinforced hydrogels are a class of soft composite materials that have seen increased use across a wide variety of biomedical applications. However, existing fabrication techniques for these hydrogels are unable to realize biologically relevant macro/mesoscale geometries. To address this limitation, this paper presents a novel air-assisted, dual-polarity electrospinning printhead that converges high-strength electric fields, with low velocity air flow to remove the collector dependency seen with traditional far-field electrospinning setups. The use of this printhead in conjunction with different configurations of deformable collection templates has resulted in the production of three classes of fiber-reinforced hydrogel prototype geometries, viz., (i) tubular geometries with bifurcations and mesoscale texturing; (ii) hollow, nontubular geometries with single and dual-entrances; and (iii) three-dimensional (3D) printed flat geometries with varying fiber density. All three classes of prototype geometries were mechanically characterized to have properties that were in line with those observed in living soft tissues. With the realization of this printhead, biologically relevant macro/mesoscale geometries can be realized using fiber-reinforced hydrogels to aid a wide array of biomedical applications.

A novel electrospinning method for self-assembled tree-like fibrous scaffolds: Microenvironment-associated regulation of MSC behavior and bone regeneration

• We fabricated biomimetic fibrous scaffolds via a novel electrospinning setup. • The scaffolds present fibrillar microenvironments with microfiber/nanonet networks. • The scaffolds differently regulate MSC behavior regarding to their fiber topographies. • Topography-sensitive mechanosensing enhances osteogenesis and bone regeneration. • The electrospun method provides an advanced approach for bone tissue engineering. Numerous studies highlight advantages of electrospun scaffolds in bone tissue engineering, in which cellular behavior is tightly affected by fiber topographical cues of scaffolds. However, the classic electrospinning setup limits a desired presentation of biomimetic fibrous microenvironments that sense mechanosignaling and regulate stem cell behavior. The aims of this study were to fabricate advanced as-spun scaffolds presenting tree-like microfiber/nanonet networks and to evaluate their regulatory potentials on behavior of human mesenchymal stem cells (hMSCs) and bone regeneration. Here we developed a novel electrospinning setup that allowed the presentation of patterned Trunk microfibers (TMF) and/or branched nanonet fibers (BNnFs) in biomimetic fibrous scaffolds. As the cellular mechanisms, anisotropic-hierarchical topography of TMF controlled behavior of hMSCs through focal adhesion formation and Yes-associated protein (YAP) induction, whereas BNnF disturbed such mechanosensing responses in the cells. The fiber microenvironment-related expression and nuclear localization of YAP were. also correlated with the potentials of as-spun scaffolds to enhance osteogenic differentiation of the hMSCs and alveolar bone defect healing in an animal model. Collectively, this study provides an advanced approach of the modified electrospinning setup for presentation of biomimetic fibrillar microenvironments in as-spun scaffolds along with their application in stem cell behavior regulation and regenerative tissue engineering.

Finite element method assisted design of needleless electrospinning systems for mass production of polymer nanofibers

Geometry design of spinneret is highly associated with nanofiber production in needleless electrospinning technologies. Current free-liquid-surface spinnerets have disadvantages, including large air/solution contact surface area, uneven electric field and fiber diameter distribution, and poor stability of polymer solution, which prevents further industrial progress. This study presented a strategy from design to simulation and experiment to develop a novel annular slit needleless electrospinning system. The effects of spinneret geometries on electric field distribution and strength were discussed by the finite element method. Numerous experiments were carried out to verify the feasibility of annular slit electrospinning. Main process parameters including solution concentration, applied voltage, and airflow velocity were studied by the response surface method. This novel needleless electrospinning apparatus shows great potential for producing nanofibers on an industrial scale.

Fabrication of Polyvinylpyrrolidone (PVP) Nanofibrous Membranes using Mushroom-Spinneret Needleless Electrospinning

Mushroom-spinneret is an improved spinneret design for needleless electrospinning apparatus, which has a bowl-shaped base with a mushroom-shaped cover. The mushroom spinneret can overcome some limitations that is often associated with the needleless electrospinning technique, i.e., high excitation voltages, poor stability of free liquid, and difficulty of controlling the spatial motion of multiple jets. In this study, we fabricate polyvinylpyrrolidone (PVP) nanofibrous membranes using mushroom-spinneret needleless electrospinning and determine the effect of solution concentration and applied voltage on the fiber morphology and diameter. The solution concentration had significant effect on the fibers diameter. When the solution concentration was increased from 8 wt% to 12 wt%, the average fibers diameter increased from 0.99 μm to 1.31 μm and the fibers diameter distribution became wider. Moreover, the average fiber diameter decreased from 1.31 μm to 1.16 μm when the applied voltage was increased from 30 kV to 45 kV. The coefficient of variations (CV) for all membrane samples ranged from 0.12 - 0.26, indicated uniform fibers.

Surface Potential Tuned Single Active Material Comprised Triboelectric Nanogenerator for a High Performance Voice Recognition Sensor.

To fabricate a high-performance and ultrasensitive triboelectric nanogenerator (TENG), choice of a combination of different materials of triboelectric series is one of the prime challenging tasks. An effective way to fabricate a TENG with a single material (abbreviated as S-TENG) is proposed, comprising electrospun nylon nanofibers. The surface potential of the nanofibers are tuned by changing the voltage polarity in the electrospinning setup, employed between the needle and collector. The difference in surface potential leads to a different work function that is the key to design S-TENG with a single material only. Further, S-TENG is demonstrated as an ultrahigh sensitive acoustic sensor with mechanoacoustic sensitivity of ≈27500mVPa-1 . Due to high sensitivity in the low-to-middle decibel (60-70dB) sounds, S-TENG is highly capable in recognizing different voice signals depending on the condition of the vocal cord. This effective voice recognition ability indicates that it has high potential to open an alternative pathway for medical professionals to detect several diseases such as neurological voice disorder, muscle tension dysphonia, vocal cord paralysis, and speech delay/disorder related to laryngeal complications.

Electrospun Hybrid Films for Fast and Convenient Delivery of Active Herb Extracts.

Herb medicines are popular for safe application due to being a source of natural herbs. However, how to deliver them in an efficacious and convenient manner poses a big challenge to researchers. In this study, a new concept is demonstrated that the electrospun polymer-based hybrid films can be a platform for promoting the delivery of a mixture of active herb extract, i.e., Lianhua Qingwen Keli (LQK), also a commercial traditional Chinese patent medicine. The LQK can be co-dissolved with the filament-forming polymeric polyvinylpyrrolidone K60 and a sweeter sucralose to prepare an electrospinnable solution. A handheld electrospinning apparatus was explored to transfer the solution into solid nanofibers, i.e., the LQK-loaded medicated films. These films were demonstrated to be composed of linear nanofibers. A puncher was utilized to transfer the mat into circular membrane a diameter of 15 mm. Two self-created methods were developed for disclosing the dissolution performances of the electrospun mats. Both the water droplet experiments and the wet paper (mimic tongue) experiments verified that the hybrid films can rapidly disintegrate when they encounter water and release the loaded LQK in an immediate manner. Based on the reasonable selections of polymeric excipients, the present protocols pave a way for delivering many types of active herb extracts in an effective and convenient manner.