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Electrospun fibers membrane is considered an efficient drug carrier for transdermal drug delivery due to its breathability and high drug loading percentage, compared with coating film. However, pollution and safety risk caused by the use of organic solvents during the solution electrospinning process limit its industrialization and direct application in the biomedical field. Herein, a fiber membrane containing tandospirone was prepared using the melt electrospinning process and to be used for sustained drug release. The process of fiber preparation is an eco‐friendly and safe process due to the characteristics of solvent‐free. The in vitro drug release results showed that the fiber membranes containing tandospirone had slower initial drug release and higher end drug release compared with coating film containing tandospirone. The sustained‐release property can be attributed to the crystalline structure of fibers and the higher‐end drug release can be attributed to the spatial packing structures in the fiber membrane. The large pores generated by the stack structure of the large fiber in the fiber membrane leads to low gas resistance (10.7 Pa), which is much lower than that of the coating film (511.2 Pa). Overall, this study presents a green and safe preparation method of fiber membrane containing tandospirone, providing an effective and adjunctive treatments for mental disorders. Highlights: The tandospirone‐loaded fiber patch was prepared using an eco‐friendly method.Burst release inhibition and higher final release of tandospirone in fibers.The fiber patch provided excellent breathability compared to coating patch.Fibers with higher crystallinity showed better controlled release. [ABSTRACT FROM AUTHOR]

The electrospun yarn for sutures has gained worldwide attention due to its fine fibers that resemble the extracellular matrix and its abundant functional sites. However, the use of a large number of toxic solvents poses safety risks and environmental pollution during production, making it challenging to directly apply electrospun yarn in the biomedical field. In this study, an environmentally friendly and safe method without toxic solvents was proposed for preparing antibacterial PLA ultrafine fiber sutures. This method involves melt electrospinning, hot‐stretching, low‐temperature plasma treatment, and chitosan grafting. The PLA ultrafine fiber sutures exhibit a high tensile strength which is 2.04 N before knotting and 1.57 N after knotting. The suture diameter is 118.7 μm and average fiber diameter is 1.72 μm. Chitosan grafted on the fiber surface provides excellent antibacterial properties for the sutures, with antibacterial rates against Escherichia coli and Staphylococcus aureus reaching 99.89% and 99.11%, respectively. The cell survival rate is 97.33%, while hemolysis rate is only 2.35%, demonstrating excellent biocompatibility of PLA ultrafine fiber sutures. This study presents a green and safe method for preparing clinically applicable absorbable antibacterial surgical sutures with high mechanical properties. Highlights: A green and safe method for preparing PLA‐CS ultrafine fiber sutures.PLA‐CS suture with a tensile strength of 2.04 N and a fiber diameter of 1.72 μm.PLA‐CS suture with good antibacterial property and biocompatibility. [ABSTRACT FROM AUTHOR]

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Medical device-related infections (DRIs), especially prevalent among critically ill patients, impose significant health and economic burdens and are mainly caused by bacteria. Severe infections often necessitate device removal when antibiotic therapy is inefficient, delaying recovery. To tackle this issue, PCL drug-eluting coated meshes were explored, and they were printed via melt electrowriting (MEW). These meshes were coated with gentamicin sulfate (GS) and tetracycline hydrochloride (TCH) and underwent FTIR analysis to confirm drug integration. Antimicrobial activity was assessed via agar diffusion assays and biofilm formation assays against bacterial strains: Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 43300, and Staphylococcus epidermidis ATCC 35984. FTIR analysis evidenced the presence of the drugs in the meshes. TCH displayed broad-spectrum antimicrobial activity against all strains, whereas GS was effective against all except S. aureus. These findings indicate the potential of cost-effective ultra-fine drug coating fibers for medical device applications, offering infection prevention during implantation. This preliminary study demonstrates the feasibility of producing drug-eluting fibers for DRI prevention through a non-toxic, fast, and cost-efficient technique, paving the way for enhanced patient care and reduced healthcare costs. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) yarn possesses the advantages of low density and exceptional mechanical properties. Through electrospinning, fibers of PP yarns can be refined from 10 to 20 μm to an ultrafine level, thereby acquiring an enlarged specific surface area and more functional sites, expanding its application in high‐value areas. Herein, vortex airflow‐assisted polymer melt differential electrospinning was proposed to fabricate PP microfiber yarns. Under the influence of an electrostatic field, molten PP automatically splits into multiple jets that are further stretched and cooled into ultrafine fibers by suction airflow induced by vortex airflow. Subsequently, multiple ultrafine fibers were twisted into PP yarns using the vortex airflow. The effects of voltage, melt feed speed, and air pressure on the PP electrospun yams formation process as well as the morphology and mechanical properties of both the yarn and fibers were investigated. The results showed that the diameter of PP fibers ranged from 3 to 5 μm. The PP microfiber yams exhibited a relatively high mechanical strength of 1.6 cN/tex under conditions of 56 kV voltage, 0.22 g/min feed rate, and 0.3 MPa air pressure. Finally, the woven fabric made from electrospun PP yams demonstrated higher hydrophobicity compared with fabric woven from commercial PP filaments, suggesting potential applications in waterproof fabrics. [ABSTRACT FROM AUTHOR]

Poly(L-lactide-co-ε-caprolactone) (PLCL) nanofiber webs is important materials for medical uses; however, the application of solution electrospinning for production has an issue with remaining solvents. Therefore, we applied the solvent-free laser-heated melt-electrospinning process (LES). The fabrication of thinner fibers through the LES is known to be rather difficult. To overcome this difficulty, a detailed investigation of the effect of laser power on fiber formation behavior was carried out. With the irradiation of the laser, the temperature of the raw fiber emerging from the nozzle increased. Subsequently, a jet ejected from the cone apex was further elongated towards a collector. With increasing the laser power, the swelling portion became smaller and shifted upstream and the temperature increased from 206 to 300 °C. Ejection of a single jet was observed when the laser power was low, whereas several jets were ejected spontaneously at the higher power. The molecular orientation of prepared fibers increased with the laser power, and the fibers started to exhibit crystalline diffractions in the WAXD analysis. The crystallinity also increased with the laser power. Enhancement of the fiber thinning at a high laser power was attributed to the reductions of viscosity and surface tension, whereas the diameter reduction with the increase of laser power was suppressed after the starting of the ejection of multiple jets at higher laser power. At an optimum condition, the homogeneous fibers with the lowest diameter of 500 nm and its CV of 16% were obtained. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic led to a huge demand for disposable facemasks. Billions were manufactured from nonbiodegradable petroleum-derived polymers, and many were discarded in the environment where they contributed to plastic pollution. There is an urgent need for biobased and biodegradable facemasks to avoid environmental harm during future disease outbreaks. Melt electrospinning is a promising alternative technique for the manufacturing of filter layers using sub-microfibers prepared from biobased raw materials such as polybutylene succinate (PBS). However, it is not yet possible to produce sub-micrometer PBS fibers or uniform nonwoven-like samples at the pilot scale, which hinders their investigation as filter layers. Further optimization of pilot-scale PBS melt electrospinning is therefore required. Here, we tested the effect of different parameters such as electric field strength, nozzle-to-collector distance and throughput on the final fiber diameter and sample uniformity during PBS melt electrospinning on a pilot-scale device. We also studied the effect of a climate chamber and an additional infrared heater on the solidification of PBS fibers and their final diameter and uniformity. In addition, a post-processing step, including a hot air stream of 90 °C for 30 s has been studied and successfully lead to a nonwoven-like structure including filaments that weld together without changing their structure. The finest fibers (1.7 µm in diameter) were produced at an applied electric field strength of −40 kV, a nozzle-to-collector distance of 5.5 cm, and a spin pump speed of 2 rpm. Three uniform nonwoven-like samples were tested as filter layers in a medical face mask by measuring their ability to prevent the transfer of bacteria, but the pore size was too large for effective retention. Our results provide insight into the process parameters influencing the suitability of melt-electrospun nonwoven-like samples as biobased and biodegradable filter materials and offer guidance for further process optimization. [ABSTRACT FROM AUTHOR]

It is challenging to simultaneously control the phase and the finer nanofiber shape to prepare a thinner poly-(vinylidene fluoride) (PVDF)-based separator. Here, an ultrafine β-PVDF nanofibrous membrane was fabricated by combining the melt electrospinning and phase-changing techniques. Temperature and electrostatic fields were introduced simultaneously to boost the β phase of PVDF. Meanwhile, phase-sacrificial polylactic acid (PLA) was employed to further reduce the diameter of the melt-electrospun fibers, which can significantly reduce the separator thickness and increase the specific surface area, addressing the main limitation of the application of nanofiber membranes in commercial separators. Furthermore, the strong interactions between the −C–F bonds in PVDF and the −CO bonds in PLA further enhanced the regular TTTT structural β phase. Besides, SiO2 and Al2O3 ceramic nanoparticles were codeposited on the β-PVDF nanofiber membrane by magnetron sputtering, which not only improves the thermostability but also prevents coating layer depowdering and thickness increase. The lithium-ion battery (LIB) with such a composite separator showed an ion conductivity of 2.242 mS/cm and a high thermostability of 150 °C. This work elucidates the controlling mechanism of the crystalline phase of PVDF-based nanofibrous membrane and provides encouraging guidance for constructing a functional layer of battery separators. [ABSTRACT FROM AUTHOR]

In melt electrospinning, accurate control of jet evolution and Taylor cone process parameters helps to control the final fiber properties. High-speed photography was employed to observe the jet’s formation process and the Taylor cone’s morphology. A multi-physics model of nonisothermal heat transfer was used to predict the fluid flow direction and velocity change. In addition, we investigated the relationships between the process parameters of the Taylor cone and the diameter of melt electrospun fiber. The results show an excellent linear relationship between the process parameters (cone angle, curvature, and Taylor cone height) and fiber diameter. According to the simulation results, the axial fluid flow keeps the maximum and accelerates continuously until the collector captures it. In addition, with the increase of voltage, the fiber strength is lower, and the crystallinity is improved. This work analyzes diameter and process parameters and offers a fresh perspective on electrostatic-fluid interaction and a method to forecast fiber diameter. [ABSTRACT FROM AUTHOR]

Melt electrospinning has been recognized as an attractive solvent-free process over the past few decades to alleviate the solvent-related problems generated by traditional electrospinning techniques. In melt spinning, the drawing process of molten jets occurs in the liquid phase region before the phase transformation. Besides, the insufficient chain flow in the solid phase results in the non-stretchable properties of the jet in this state. This analysis predicted the phase transition displacement in the polymer jet during the melting process using a two-dimensional non-isothermal flow model integrated with an electric field. High-speed photography was employed to collect photographs of the phase transition point of the jet to verify the simulation results. Additionally, we evaluated the diameters of fibers manufactured with various phase transition displacements induced by different applied voltages. The findings of the experiments reveal that as the applied voltage is enhanced, the freezing point of the jet becomes gradually closer to the nozzle side, and the solidification length significantly reduces, resulting in smaller fiber diameter. Moreover, the results mentioned above are consistent with the law predicted by the simulation, proving the feasibility and accuracy of the model. This work will provide potential guidance for the study of nanoscale melt fibers from the perspective of fluid phase transformation. [ABSTRACT FROM AUTHOR]

Electrospinning is the simplest and most widely used technology for producing ultra-thin fibers. During electrospinning, the high voltage causes a thin jet to be launched from the liquid polymer and then deposited onto the grounded collector. Depending on the type of the fluid, solution and melt electrospinning are distinguished. The morphology and physicochemical properties of the produced fibers depend on many factors, which can be categorized into three groups: process parameters, material properties, and ambient parameters. In the biomedical field, electrospun nanofibers have a wide variety of applications ranging from medication delivery systems to tissue engineering scaffolds and soft electronics. Many of these showed promising results for potential use as medical devices in the future. Medical devices are used to cure, prevent, or diagnose diseases without the presence of any active pharmaceutical ingredients. The regulation of conventional medical devices is strict and carefully controlled; however, it is not yet properly defined in the case of nanotechnology-made devices. This review is divided into two parts. The first part provides an overview on electrospinning through several examples, while the second part focuses on developments in the field of electrospun medical devices. Additionally, the relevant regulatory framework is summarized at the end of this paper. [ABSTRACT FROM AUTHOR]

Limbal stem cells (LSCs) are of paramount importance in corneal epithelial tissue repair. The cornea becomes opaque in case of limbal stem cell deficiency (LSCD), which may cause serious damage to the ocular visual function. There are many techniques to restore damaged epithelium, one of which is the transplantation of healthy cultured LSCs, usually onto a human amniotic membrane or onto bio-based engineered scaffolds in recent years. In this study, melt electrospun polylactic acid (PLA) was modified by silk fibroin or gelatin and further cultured with LSCs originating from three different donors. In terms of physicochemical properties, both modifications slightly increased PLA scaffold porosity (with a significantly larger pore area for the PLA/gelatin) and improved the scaffolds' swelling percentage, as well as their biodegradation rate. In terms of the scaffold application function, the aim was to detect/visualize whether LSCs adhered to the scaffolds and to further determine cell viability (total number), as well as to observe p63 and CK3 expressions in the LSCs. LSCs were attached to the surface of microfibers, showing flattened conformations or 3D spheres in the formation of colonies or agglomerations, respectively. All scaffolds showed the ability to bind the cells onto the surface of individual microfibers (PLA and PLA/gelatin), or in between the microfibers (PLA/silk fibroin), with the latter showing the most intense red fluorescence of the stained cells. All scaffolds proved to be biocompatible, while the PLA/silk fibroin scaffolds showed the highest 98% viability of 2.9 × 106 LSCs, with more than 98% of p63 and less than 20% of CK3 expressions in the LSCs, thus confirming the support of their growth, proliferation and corneal epithelial differentiation. The results show the potential of these bio-engineered scaffolds to be used as an alternative clinical approach. [ABSTRACT FROM AUTHOR]

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polycaprolactone (PCL) is biodegradable and non-toxic, making it an eco-friendly polymer with various medical applications. In order to increase the stability of PCL used in the field of medical applications, it is necessary to be able to produce fibers with a melt electrospinning method that does not use toxic hydrophobic solvents. However, PCL has very high viscosity and low conductivity, making melt electrospinning difficult. This study presents natural additives enabling the solvent-free melt electrospinning of PCL, wherein the physical properties (i.e., conductivity and viscosity) of the additive-mixed PCL are analyzed. Among the natural additives added to PCL, 7 wt% gallic acid increased conductivity by 81 times and decreased viscosity by 1/8526 times, showing the best results. We believe that our study, improving the physical properties of melt PCL by adding natural additives, will be of great help to the development of the melt electrospinning method of PCL. [ABSTRACT FROM AUTHOR]

The fabrication process of polymer fibers has been analyzed in various ways, and several studies have been conducted to develop new processes and optimize existing ones. Several studies have been conducted on the electrospinning process, which can easily fabricate nanofibers, and the development of materials manufactured through electrospinning has also been investigated. However, research on the nanofiber fabrication and processing of thermoplastic polymers, such as polypropylene (PP), polyethylene and polyethylene terephthalate, is relatively lacking. Therefore, research on nanofiber fabrication is essential. In this study, PP fibers were successfully manufactured through a melt electrospinning/blowing process, which combined melt blowing and electrospinning. To analyze the melt electrospinning/blowing process, the dynamic behavior of the spinning process was observed using a charge‐coupled device camera in real time, and the effects of the different spinning conditions were compared and analyzed. As the hot air or high voltage was increased, the spinning jet area tended to increase. In addition, the average diameter of the fabricated fibers tended to decrease as a high voltage was applied at a hot air pressure of 0.01 MPa; conversely, the average diameter tended to increase at a hot air pressure of 0.03 MPa. A similar trend was observed for the tensile stresses in the PP web fabrics. The polymer fibers produced by this melt electrospinning/blowing process can be applied as a production process for nanomembranes, filters and battery separators. © 2022 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

The melt-electrospinning performance of poly (butyleneadipate-co-terephthalate) (PBAT) was investigated, and the relationship between the melt differential electrospinning process parameters and properties of the resultant PBAT fibers were studied. The results indicated that the fiber diameter decreased and its diameter distribution decreased at first and then tended to increase with an increase in spinning temperature. With an increase in spinning voltage, the fiber diameter decreased and the distribution was uniform. Meanwhile, the mechanical properties of the fiber membranes were improve gradually. The optimal fiber fineness and uniformity were obtained at a spinning distance of 9 cm, a spinning temperature of 260 °C, and a spinning voltage of 45 kV. The obtained fibers exhibited a diameter of 4.31 μm, a standard diameter distribution deviation of 0.76. The fiber membranes obtained tensile strength of 9.9 MPa and elongation at break of 111.2 %. [ABSTRACT FROM AUTHOR]

Polycaprolactone (PCL) scaffold is a common biological material for tissue engineering, owing to its good biocompatibility, biodegradability and plasticity. However, it is not suitable for osteoblast adhesion and regeneration of bone tissue due to its non-biological activity, poor mechanical strength, slow degradation speed, smooth surface and strong hydrophobicity. To improve the mechanical properties and biocompatibility of PCL scaffold, the PCL/nHA scaffolds were prepared by melting and blending different proportions of nano-hydroxyapatite (nHA) with PCL by the near-field direct-writing melt electrospinning technology in this study. The morphology, porosity, mechanical properties and in vitro biocompatibility of the PCL/nHA scaffolds were studied. The results showed that when the proportion of nHA was less than or equal to 25%, PCL/nHA composite scaffolds were easily formed in which bone marrow mesenchymal stem cells proliferated successfully. When the proportion of nHA was 15%, the PCL/nHA composite scaffolds had excellent structural regularity, good fiber uniformity, outstanding mechanical stability and superior biocompatibility. The PCL/nHA composite scaffolds were ideal scaffold materials, which would broaden their applications for bone tissue engineering. [ABSTRACT FROM AUTHOR]

Melt electrospinning is a convenient method for producing nonwoven materials from polymers with limited solubility, such as polyolefins and its blends. In this work, we investigated the process of electrospinning from melt of blends of thermodynamically immiscible polymers: polypropylene and polystyrene. Nonwoven materials with an average fiber diameter of 1.5–4 μm have been obtained. Typically, morphology of blended nonwoven material can be further modified by selective removal of one of the components. However, it was found that after removal of polystyrene from the produced materials, the fibers do not undergo significant changes in the surface morphology. At the same time, fiber fragments having a length of 5–100 μm appear and their number grows as the content of polystyrene in the initial material increases. According to X‐ray data, the supramolecular structure of polypropylene changes in the electrospinning process: a transition from a stable α‐form to a low‐ordered mesophase occurs. On the other hand, a reverse transition to crystallites of the α‐form of polypropylene was observed after polystyrene was removed with hot chloroform. All materials exhibit superhydrophobic properties and their wetting occurs according to the Wenzel model. Sorption capacity of the resulting materials is up to 90 g/g for motor oil. [ABSTRACT FROM AUTHOR]

Fibers with diameters in the lower micrometer range have unique properties suitable for applications in the textile and biomedical industries. Such fibers are usually produced by solution electrospinning, but this process is environmentally harmful because it requires the use of toxic solvents. Melt electrospinning is a sustainable alternative but the high viscosity and low electrical conductivity of molten polymers produce thicker fibers. Here, we used multifunctional biobased dyes as additives to improve the spinnability of polylactic acid (PLA), improving the spinnability by reducing the electrical resistance of the melt, and incorporating antibacterial activity against Staphylococcus aureus. Spinning trials using our 600-nozzle pilot-scale melt-electrospinning device showed that the addition of dyes produced narrower fibers in the resulting fiber web, with a minimum diameter of ~9 µm for the fiber containing 3% (w/w) of curcumin. The reduction in diameter was low at lower throughputs but more significant at higher throughputs, where the diameter reduced from 46 µm to approximately 23 µm. Although all three dyes showed antibacterial activity, only the PLA melt containing 5% (w/w) curcumin retained this property in the fiber web. Our results provide the basis for the development of environmentally friendly melt-electrospinning processes for the pilot-scale manufacturing of microfibers. [ABSTRACT FROM AUTHOR]

Several types of chemotherapeutic agents are used in cancer treatment. Among these agents, daunorubicin hydrochloride which is a cell-cycle non-specific antitumor agent is commonly used for treating various types of cancers. This work aims to design daunorubicin loaded polymeric fibre meshes with melt electrospinning using poly (ε-caprolactone) (PCL) polymer for potential localized antitumor application. The prepared meshes had smooth surface with uniform distribution of daunorubicin as indicated by fluorescent microscope. The meshes thickness increased by increasing the daunorubicin concentration loaded into the PCL fibres. The process of melt electrospinning did not result in any chemical interactions between PCL and daunorubicin neither changed the crystalline structure of these components. Concentration dependent slow-release profile of daunorubicin from the melt electrospun fibres was achieved. Cytotoxicity of the released daunorubicin was assessed on melanoma and ovarian cancer cells and revealed that the cytotoxicity was increased by increasing the time of meshes incubation due to the slow-release profile of daunorubicin. These results prove that PCL-based fibre meshes loaded with daunorubicin are a suitable therapeutic option for local application of antitumour agents. This can enhance the therapeutic outcomes and reduce the unwanted toxicities of these anticancer molecules. [Display omitted] [ABSTRACT FROM AUTHOR]

Melt electrospinning is a simple, versatile, and widely used technique for the production of microfibers and sub-microfibers. Polybutylene succinate (PBS) is a promising raw material for the preparation of melt-electrospun fibers at the laboratory scale. The inclusion of additives in the PBS melt can reduce the final fiber diameter, but economically feasible larger-scale processes remain challenging. The fiber diameter can also be reduced by machine optimization, although this is expensive due to the complexity of melt-electrospinning devices. Changes in electrical field polarity have provided a low-cost strategy to reduce the diameter of fibers produced by solution-electrospinning, but there is little information about the effect of this parameter on the final diameter of melt-electrospun fibers. We therefore determined the effect of field polarity on the diameter of melt-electrospun PBS fibers at the laboratory scale and investigated the transferability of these results to our 600-nozzle pilot-scale device. Changing the polarity achieved a significant reduction in fiber diameter of ~50% at the laboratory scale and ~30% at the pilot scale, resulting in a minimum average fiber diameter of 10.88 µm. Although the effect of field polarity on fiber diameter was similar at both scales, the fibers in the web stuck together at the laboratory scale but not at the pilot scale. We have developed an inexpensive method to reduce the diameter of melt-electrospun PBS fibers and our data provide insight into the transferability of melt electrospinning from the laboratory to a pilot-scale machine. [ABSTRACT FROM AUTHOR]

The laser-assisted melt electrospinning (LES) method was utilized for the preparation of poly(L-lactide-co-ε-caprolactone) (PLCL) fibers. During the process, a carbon dioxide laser was irradiated, and voltage was applied to the raw fiber of PLCL. In situ observation of fiber formation behavior revealed that only a single jet was formed from the swelling region under the conditions of low laser power and applied voltage and feeding rate, whereas multiple jets and shots were produced with increases in these parameters. The formation of multiple jets resulted in the preparation of thinner fibers, and under the optimum condition, an average fiber diameter of 0.77 μm and its coefficient of variation of 17% was achieved without the formation of shots. The estimation of tension and stress profiles in the spin-line was also carried out based on the result of in situ observation and the consideration that the forces originated from surface tension, electricity, air friction, and inertia. The higher peak values of tension and stress appearing near the apex of the swelling region corresponded to the formation of thinner fibers for the condition of single-jet ejection. Analyses of the molecular orientation and crystallization of as-spun fibers revealed the formation of a wide variation of higher order structure depending on the spinning conditions. [ABSTRACT FROM AUTHOR]

In this study, the effect of the heating temperature of the spinneret on the melt electrospinning process under the condition of application of auxiliary heating was investigated, in a systematical and comprehensive way. The temperature distribution of the melt jet during the melt electrospinning process was simulated by finite element software in order to provide a good deal of insight into the experimental results. In addition, high-speed photography was adopted to capture images of jet formation and jet motion during the melt electrospinning process. The experimental results indicated that the cooling rate of the polypropylene jet decreases obviously under the condition of auxiliary heating; in addition, the higher spinneret temperature leads to greater drafting force, a drawing fiber drafting rate, and greater jet whipping motion, which is conducive to secondary drawing and refinement of the jet. [ABSTRACT FROM AUTHOR]

Recent developments in melt electrowriting (MEW), a high‐resolution additive manufacturing technology, have led to increases in scaffold complexity. However, MEW scaffolds are currently characterized ex situ, which causes time–consuming iterations of characterization and fabrication that limit scaffold throughput and more widespread use of the technology. For the first time, an in situ method to characterize the 3D microstructure of MEW scaffolds using optical coherence tomography (OCT) is described. Calculations of microstructural features are performed on OCT data using a custom algorithm, demonstrating close correspondence with scanning electron microscopy (SEM). For example, OCT calculations of fiber diameter and scaffold thickness are within an average of 0.31 and 1.79 μm, respectively, of corresponding SEM–derived calculations. Additionally, the 3D capabilities of OCT enable the nondestructive characterization of scaffolds with depth–varying microstructures, overcoming some main limitations of SEM. Finally, in situ characterization is achieved by integrating the OCT scanner within an MEW printer, enabling the scaffold microstructure to be evaluated and optimized during manufacture. This new capability represents an important step toward achieving an efficient fabrication–characterization cycle with the guaranteed scaffold quality and reproducibility required to validate the manufacturing process.

Recycling is the most effective way to dispose of waste polymer materials. It can not only reduce the harm of polymer materials to the natural environment, but also achieve the purpose of saving cost and turning waste into treasure. A self-made melt differential electrospinning device was used to recover the degraded polypropylene (PP) non-woven fabric as a raw material, and the special powder for recycling and degrading PP non-woven fabric after acid treatment and adding different plasticizers with a mass fraction of 10%. A blend of materials of sodium stearate, acetyl tributyl citrate (ATBC), and dioctyl adipate (DOA) was spun, and a nanofiber membrane was prepared at 300 ℃. The optimum degradation time of PP nonwoven fabric spinning and the effect of adding different plasticizers on the morphology, oil absorption performance and reusability of PP-degraded non-woven fabric nanofibers were investigated. Studies have shown that the addition of plasticizer ATBC works best. When the spinning voltage is 40 kV, the spinning distance is 70 mm, the spinning temperature is 300 ℃, and the ATBC mass fraction is 10%, the fiber diameter is as fine as 1.13 μm. The fiber membrane oil absorption ratio is 115.4 g/g, and the oil retention ratio is 70.3 g/g, which are 4 times and 3 times that of the initially commercially available PP nonwoven fabric, and has good reusability.

Polycaprolactone (PCL) is biodegradable and non-toxic, making it an eco-friendly polymer with various medical applications. In order to increase the stability of PCL used in the field of medical applications, it is necessary to be able to produce fibers with a melt electrospinning method that does not use toxic hydrophobic solvents. However, PCL has very high viscosity and low conductivity, making melt electrospinning difficult. This study presents natural additives enabling the solvent-free melt electrospinning of PCL, wherein the physical properties (i.e., conductivity and viscosity) of the additive-mixed PCL are analyzed. Among the natural additives added to PCL, 7 wt% gallic acid increased conductivity by 81 times and decreased viscosity by 1/8526 times, showing the best results. We believe that our study, improving the physical properties of melt PCL by adding natural additives, will be of great help to the development of the melt electrospinning method of PCL.

Degradable polylactide (PLA) nanofibers can be prepared by solvent free melt electrospinning technology which is promising,challenging and green. The nanofiber membrane prepared by this method have high porosities and strong adsorption capacities,and thus are useful for treating the environmental pollution efficiently. The organic montmorillonite(OMMT) was introduced into PLA, and the PLA/OMMT nanofiber membrane were prepared at 260℃ by using a self-made melt differential electrospinning device. The effect of OMMT content of PLA nanofiber membrane on the morphology,the oil absorption property,the air filtration performance and the degradability was investigated, and the optimum OMMT content was obtained. The research shows that the thermal stability of PLA is increased and the crystallinity of PLA is decreased significantly after adding OMMT. When the OMMT content is 2%,the diameter of the fiber reaches 450nm. The oil absorption rate of the nanofiber membrane is 133.5g/g which is 4-5 times higher than that of commercially available PP non-wovens,and the oil holding rate is 84.2g/g. Moreover,the nanofiber membrane has good reuse performance. The air filtration efficiency of the nanofiber membrane for dust particles(≥ 0.3μm) is 99.31%,reaching the European standard H11 filtration class. The degradation of PLA/OMMT nanofiber membrane is improved comparing with the pure PLA, which reduces the second pollution and accords with the requirements of industrial green environmental protection.

Polycaprolactone (PCL) scaffold is a common biological material for tissue engineering, owing to its good biocompatibility, biodegradability and plasticity. However, it is not suitable for osteoblast adhesion and regeneration of bone tissue due to its non-biological activity, poor mechanical strength, slow degradation speed, smooth surface and strong hydrophobicity. To improve the mechanical properties and biocompatibility of PCL scaffold, the PCL/nHA scaffolds were prepared by melting and blending different proportions of nano-hydroxyapatite (nHA) with PCL by the near-field direct-writing melt electrospinning technology in this study. The morphology, porosity, mechanical properties and in vitro biocompatibility of the PCL/nHA scaffolds were studied. The results showed that when the proportion of nHA was less than or equal to 25%, PCL/nHA composite scaffolds were easily formed in which bone marrow mesenchymal stem cells proliferated successfully. When the proportion of nHA was 15%, the PCL/nHA composite scaffolds had excellent structural regularity, good fiber uniformity, outstanding mechanical stability and superior biocompatibility. The PCL/nHA composite scaffolds were ideal scaffold materials, which would broaden their applications for bone tissue engineering.

The goal of scaffold-based tissue engineering is to create synthetic replacements for natural tissues. Since tissues are comprised of composite structures, it is challenging for a single biomaterial to appropriately mimic the cellular and extracellular natural environment. To incorporate multiple biomaterials into multiphasic scaffolds, additive manufacturing (3D printing) technologies have arisen as a universal scaffold fabrication platform. However, combining multiple printed biomaterials is technically difficult since many printing processes rely on fundamentally different operating principles. Furthermore, commercial equipment is often cost prohibitive, and there remains limited open-source alternatives. To address the lack of equipment, systematic engineering design was applied to build an open-source 3D bioprinter capable of printing with multiple materials using multiple technologies. The design requirements were identified through a user-centred design process with the overarching aim of being a multi-material, multi-technology system while adhering to engineering standards (AS IEC 61010). The system was constructed to be open source, and detailed diagrams, parts lists, computer-aided design (CAD) models, standard operating procedures (SOP's) and cost breakdowns on each subsystem are provided. To validate and test the design, 4 popular extrusion and electrohydrodynamic printing processes were tested: inks, solution electrospinning, melt electrospinning and melt extrusion. To demonstrate the utility of the Biofabricator for creating multi-material, multi-technology scaffolds, 4 multiphasic scaffolds were designed and presented as case studies. The open-source Biofabricator is an advanced bioprinting platform capable of fabricating multi-material, multi-technology scaffolds to support cutting-edge future research in tissue engineering. [ABSTRACT FROM AUTHOR]

In this study, the jet formation progress, jet motion, resultant fiber diameter, fiber mat morphology, inner structures and mechanical properties of the fibers prepared at different heating temperatures via melt electrospinning system were studied, in a comprehensive and systematic manner. The temperature distribution of the melt electrospinning configuration was simulated, in order to provide a good deal of insight into the experimental results. High-speed photography was adopted to capture the images of jet formation process and jet motion during melt electrospinning. The experimental results showed that higher heating temperature at the spinneret results in shorter jet formation time, smaller fiber diameter, more disordered fiber mat, lower degree of crystallinity and strength. The simulation works was carried out, aimed at facilitating to deeply understand the experimental results. [ABSTRACT FROM AUTHOR]

Melt electrospinning has been developed in the last decade as an eco-friendly and solvent-free process to fill the gap between the advantages of solution electrospinning and the need of a cost-effective technique for industrial applications. Although the benefits of using melt electrospinning compared to solution electrospinning are impressive, there are still challenges that should be solved. These mainly concern to the improvement of polymer melt processability with reduction of polymer degradation and enhancement of fiber stability; and the achievement of a good control over the fiber size and especially for the production of large scale ultrafine fibers. This review is focused in the last research works discussing the different melt processing techniques, the most significant melt processing parameters, the incorporation of different additives (e.g., viscosity and conductivity modifiers), the development of polymer blends and nanocomposites, the new potential applications and the use of drug-loaded melt electrospun scaffolds for biomedical applications. [ABSTRACT FROM AUTHOR]

Electrospinning is commonly used for fabrication of polymer fibers. Melt electrospinning, instead of the commonly used solution electrospinning, offers many advantages in generating polymer fibers without using solvents. However, polymer melts have high viscosity which poses major limitations in producing low diameter fibers. Here, melt electrospinning is investigated at elevated temperatures in inert atmosphere to reduce fiber diameters while suppressing thermal degradation. Two types of spinneret configurations, syringe and wire, with two distinct outcomes are studied. In syringe‐based electrospinning, increasing the nozzle temperature from 300 to 360 °C in nitrogen reduced fiber diameter significantly from 33 ± 5 to 10 ± 4 µm. Electrospinning in nitrogen leads to formation of fibers even at a high nozzle temperature of 360 °C, while this temperature leads to thermal degradation when spinning in air. In contrast, increasing the temperature of wire electrospinning setup do not lead to a noticeable reduction in diameter. This is attributed to the viscosity‐dependent flow rate in this method. Increasing the temperature leads to increased flow rates, promoting the formation of thicker fibers, while the increased stretchability promotes the formation of thinner fibers. The results clearly demonstrate advantages of developing polymer microfibers in inert atmosphere to avoid thermal degradation with a temperature‐independent flow control. [ABSTRACT FROM AUTHOR]

The electric field and temperature are the two important factors that influence the diameter and properties of fiber in the melt electrospinning process. It is commonly known that the polymer jet behavior is governed by the electric field within spinning area. In present work, a comprehensively-designed and properly-conducted analysis was carried out to investigate into the effects of electric field on the jet behaviors, diameters, crystalline structure and mechanical properties of the resultant fibers. An auxiliary electrode was invited to enhance the electric field strength. The high-speed photography was adopted to capture the jet motion, and also, the numerical simulation was used to understand the electric field distribution. By making use of the whipping amplitude and whipping frequency, the characteristics of jet behavior were described. It was found that by applying an auxiliary electrode, the average fiber diameter reduced from 61.01 µm to 9.06 µm, and the crystallinity and strength of the fiber was improved with the help of the higher electric filed intensity. In addition, the more uniform electric field would produce finer and more uniform fiber because of the more stable jet motion. [ABSTRACT FROM AUTHOR]

Melt electrospinning is a polymer processing technology for the manufacture of microfibers and nanofibers. Additives are required to reduce the melt viscosity and increase its conductivity in order to minimize the fiber diameter, and can also impart additional beneficial properties. We investigated the preparation of polybutylene succinate (PBS) microfibers incorporating different weight percentages of two multifunctional additives (the organic dye curcumin and inorganic silver nanoparticles) using a single-nozzle laboratory-scale device. We determined the influence of these additives on the polymer melt viscosity, electrical conductivity, degradation profile, thermal behavior, fiber diameter, and antibacterial activity. The formation of a Taylor cone followed by continuous fiber deposition was observed for compounds containing up to 3% (w/w) silver nanoparticles and up to 10% (w/w) curcumin, the latter achieving the minimum average fiber diameter of 12.57 µm. Both additives reduced the viscosity and increased the electrical conductivity of the PBS melt, and also retained their specific antibacterial properties when compounded and spun into fibers. This is the first report describing the effect of curcumin and silver nanoparticles on the properties of PBS fibers manufactured using a single-nozzle melt-electrospinning device. Our results provide the basis to develop environmentally benign antibacterial melt-electrospun PBS fibers for biomedical applications.

Daunorubicin hydrochloride is a cell-cycle non-specific antitumor drug with a high therapeutic effect. The present study outlines the fabrication of daunorubicin hydrochloride-loaded poly (ε-caprolactone) (PCL) fibrous membranes by melt electrospinning for potential application in localized tumor therapy. The diameters of the drug-loaded fibers prepared with varying concentrations of daunorubicin hydrochloride (1, 5, and 10 wt%) were 2.48 ± 1.25, 2.51 ± 0.78, and 2.49 ± 1.58 μm, respectively. Fluorescence images indicated that the hydrophobic drug was dispersed in the hydrophilic PCL fibers in their aggregated state. The drug release profiles of the drug-loaded PCL melt electrospun fibrous membranes were approximately linear, with slow release rates and long-term release periods, and no observed burst release. The MTT assay was used to examine the cytotoxic effect of the released daunorubicin hydrochloride on HeLa and glioma cells (U87) in vitro. The inhibition ratios of HeLa and glioma cells following treatment with membranes prepared with 1, 5, and 10 wt% daunorubicin hydrochloride were 62.69%, 76.12%, and 85.07% and 62.50%, 77.27%, and 84.66%, respectively. Therefore, PCL melt electrospun fibrous membranes loaded with daunorubicin hydrochloride may be used in the local administration of oncotherapy.

• An innovative interfacial evaporation module was prepared by electrospinning. • The evaporation rate is 1.29 kg m−2 h−1 under sunlight irradiation with 1 sun. • The evaporation efficiency is 81.0% under sunlight irradiation with 1 sun. • The fibrous membranes exhibiting the long-term durability and good reusability. Freshwater is a crucial resource for human life existence, diminishing freshwater resources and ever-increasing water demand had sprouted interest in desalination and water recycling. Solar energy has been utilized as an alternative to fossil fuels for energy requirements in water recycling. Efficient photo-thermal conversion materials and evaporation module are indispensable for such systems. In the current study, an innovative double-layer interfacial evaporation module of polylactic acid (PLA) fibrous membrane loaded with Chinese ink nanoparticles is synthesized. Electrospun layer of micro-scale diameter with enhanced hydrophilic properties is employed as water transport layer, while solution of electrospun layer of nano-scale diameter fiber loaded with Chinese ink nanoparticles functioned as evaporation interface. Ideal dispersion of Chinese ink nanoparticles in the PLA nanofiber is ensured with Field Emission Scanning Electron Microscopy (FE-SEM). Experiments with designed evaporation module indicates that double-layer membrane with 2 wt% Chinese ink nanoparticles has achieved an evaporation rate of at 1.29 kg cm−2 h−1 at 81.0% efficiency under simulated sunlight with a illumination intensity of 1 sun (1 sun = 1 kW/m2), which is significantly higher than the pure water and conventional membranes without Chinese ink nanoparticles. The developed fibrous membrane is able to retain its enhanced characteristics even after 20 cycles under same operating conditions during the durability test. The designed evaporation module is a promising candidate for conversion of waste water to clean water. [ABSTRACT FROM AUTHOR]

Melt electrospinning is a fast-emerging technique for fibre formation. While the process is similar to solution electrospinning, the absence of solvents broadens the applications, avoiding the potential toxicity of solvent residues and enables the usage of non-dissolvable polymers. In this article, the influence of selected melt electrospinning process parameters (tip-to-collector distance, voltage, and melt temperature) on fibre diameter and diameter distribution was investigated. The screening experiments indicated that the lowest fibre diameter median was 2.19 μm. Based on the dependencies between each process parameter and median fibre diameter, the authors used response-surface plots to determine the optimal conditions to produce fibres with the desired fibre diameters. The lowest fibre diameters were obtained with the following process parameter input values: temperature, 348°C; voltage, 19 kV; and tip-to-collector distance, 3 cm. The obtained fibres indicated that the average value of fibre diameter medians decreased in comparison to the screening experiment and the median fibre diameter for the sample "Optim." was 1.27 μm. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years drug-loaded nanofibers prepared using solution electrospinning methods have been actively studied. However, there are a number of problems connected to their solution electrospinning with respect to medical applications because of the hazards associated with the residual solvents. To avoid the use of solvents in this study we prepared and evaluated drug-loaded polylactide (PLA) fiber webs using a laser-electrospinning (LES) type of a melt electrospinning process. The structures and properties of the obtained drugloaded PLA fiber webs were evaluated by scanning electron microscopy, fluorescence microscopy, wide-angle X-ray diffraction and UV-vis spectrometry. As shown by the various characterization techniques, we employed LES to prepare PLA nanofiber webs with average fiber diameters of 4.21 and 0.67 lm. Additionally, the webs were loaded with argatroban, a thrombin inhibitor, resulting in amorphous structures for both the argatroban and the PLA matrix. An in-vitro investigation of the drug release behavior of the webs revealed that higher release rates occurred for the fiber samples with the small fiber diameters, particularly in comparison with melt spun fibers with an average diameter of 150 lm. Overall, we expect that the herein described drug-loaded PLA nanofiber webs can be applied as medical materials with drug delivery system functions. [ABSTRACT FROM AUTHOR]

Abstract A novel fibre printing apparatus was developed, employing the principles of additive printing and melt electrospinning, and used to form fibre mats. Five commercially available polyamide and polyolefin-based polymers were tested for the production of high-efficiency media for air filtration using melt electrospinning. The mats were tested for PM 1 filtration efficiency. Polyamide-based polymer was revealed as the most useful for printing, producing mats with optimum morphology (median fibre diameter of 5.04 μm and interquartile range of 4.35 μm). A total of 11 samples from 68 originally prepared ones met the requirements of PM 1 class filters. The filtration efficiency (e PM 1) ranged from 55% to 80%, while the quality factor varied between 0.013 and 0.037 Pa-1, with a comparatively low basis weight (86.03–376.81 g/m2), indicating the high potential of such media for applications in the air filtration sector. Highlights • A novel fibre printing melt electrospinning apparatus was developed. • Optimal conditions for air filtration mat formation were determined. • High dispersion of fibre diameters observed from <1 to 15 μm. • E PM 1 ranged from 55% to 80%. • Quality factor was higher than that of off-shelf materials of similar efficiency. [ABSTRACT FROM AUTHOR]

A facile route was proposed to fabricate core–sheath microfibers, and the relationships among processing parameters, crystalline structures and the mechanical properties were investigated. The compression molded poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)/poly(L -lactic acid) (PLLA) strip enhanced the spinnability of PHBH and the mechanical properties of PLLA as well. The core–sheath ratio of the fibers was determined by the prefab strip, while the PLLA sheath component did not completely cover the PHBH core component due to the weak interfacial tension between the melts of PHBH and PLLA. A rotational target was applied to collect aligned fibers, which were further drawn in a water bath. The tensile strength and the modulus of as-spun and drawn fibers increased with increasing the take-up velocities. When the take-up velocity was above 500 m/min, the jet became unstable and started to break up at the tip of the Taylor cone, decreasing the mechanical properties of the fibers. The drawing process facilitated the crystallization of PLLA and PHBH, and the tensile strength and the modulus increased linearly with the increasing the draw ratio. The crystal information displayed from wide-angle X-ray diffraction patterns and differential scanning calorimetry heating curves supported the results of the tensile tests. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wound dressing, which can release anti‐infectives in a controlled way, is taking an important role in the treatment and recovery of the open wound. An adequate release of antibiotics can prevent infections from microorganisms effectively. Among the new candidates of fabricating base materials for wound dressing, electrospinning fiber mats are attracting numerous attentions for their excellent performance in controlled drug delivery. The drug release behavior of electrospinning fiber mats can be tuned by changing the chemical components and the geometric structures of the mats. In this study, fiber mats with different geometric structures, which composed of poly‐ε‐caprolactone (PCL), polyethylene glycol (PEG), and ciprofloxacin (Cip) with different blending ratios, were successfully fabricated by direct‐writing melt electrospinning, and the release behavior of Cip were subsequently investigated in vitro. The results showed that the addition of PEG improved the hydrophilicity of the mats, which in turn affected the manner of drug release. The presence of PEG changed the releasing mechanism from a non‐Fickian diffusion into Fickian diffusion, which indicated that the diffusion of Cip from the composite fiber mats became the main factor of drug release instead of polymer degradation. Besides, with the same composition but different geometric structures, the drug release behavior is of significant difference. Therefore, all the Cip‐loaded composite fiber mats showed antibacterial activities but with different efficiency. In summary, the release of the drug could be controlled by adding PEG and changing the geometric structures according to the different requirement of wound dressings. [ABSTRACT FROM AUTHOR]