A mini review on the generation of crimped ultrathin fibers via electrospinning: Materials, strategies, and applications

Optimization of Electrospun Bilayer Vascular Grafts through Assessment of the Mechanical Properties of Monolayers

Small-diameter vascular grafts must be obtained with the most appropriate materials and design selection to harmoniously display a variety of features, including adequate tensile strength, compliance, burst strength, biocompatibility, and biodegradability against challenging physiological and hemodynamic conditions. In this study, monolayer vascular grafts with randomly distributed or radially oriented fibers are produced using neat, blended, and copolymer forms of polycaprolactone (PCL) and poly(lactic acid) (PLA) via the electrospinning technique. The blending ratio is varied by increasing 10 in the range of 50-100%. Bilayer graft designs are realized by determining the layers with a random fiber distribution for the inner layer and radial fiber orientation for the outer layer. SEM analysis, wall thickness and fiber diameter measurements, tensile strength, elongation, burst strength, and compliance tests are done for both mono- and bilayer scaffolds. The findings revealed that the scaffolds made of neat PCL show more flexibility than the neat PLA samples, which possess higher tensile strength values than neat PCL scaffolds. Also, in blended samples, the tensile strength values do not show a significant improvement, whereas the elongation values are enhanced in tubular samples, depending on the blending ratio. Also, neat poly(l-lactide-co-caprolactone) (PLCL) samples have both higher elongation and strength values than neat and blended scaffolds, with some exceptions. The blended specimens comprising a combination of PCL and PLA, with blending ratios of 80/20 and 70/30, exhibited the most elevated burst pressures. Conversely, the PLCL scaffolds demonstrated superior compliance levels. These findings suggest that the blending approach and fiber orientation offer enhanced burst strength, while copolymer utilization in PLCL scaffolds without fiber alignment enhances their compliance properties. Thus, it is evident that using a copolymer instead of blending PCL and PLA and combining the PLCL layer with PCL and PLA monolayers in bilayer vascular graft design is promising in terms of mechanical and biological properties.

Biomimetic crimped/aligned microstructure to optimize the mechanics of fibrous hybrid materials for compliant vascular grafts

The precise mechanical properties of many tissues are highly dependent on both the composition and arrangement of the nanofibrous extracellular matrix. It is well established that collagen nanofibers exhibit a crimped microstructure in several tissues such as blood vessel, tendon, and heart valve. This collagen fiber arrangement results in the classic non-linear 'J-shaped' stress strain curve characteristic of these tissues. Synthetic biomimetic fibrous materials with a crimped microstructure similar to natural collagen demonstrate similar mechanical properties to natural tissues. The following work describes a nanofabrication method based on electrospinning used to fabricate two component hybrid electrospun fibrous materials that mimic the microstructure and mechanical properties of vascular tissue. The properties of these samples can be precisely and predictably optimized by modifying fabrication parameters. Tubular grafts with biomimetic microstructure were constructed to demonstrate the potential of this fabrication method in vascular graft replacement applications. It was possible to closely match both the overall geometry and the compliance of specific blood vessels by optimizing graft microstructure.

The Potential of Electrospinning to Enable the Realization of Energy-Autonomous Wearable Sensing Systems

The market for wearable electronic devices is experiencing significant growth and increasing potential for the future. Researchers worldwide are actively working to improve these devices, particularly in developing wearable electronics with balanced functionality and wearability for commercialization. Electrospinning, a technology that creates nano/microfiber-based membranes with high surface area, porosity, and favorable mechanical properties for human in vitro and in vivo applications using a broad range of materials, is proving to be a promising approach. Wearable electronic devices can use mechanical, thermal, evaporative and solar energy harvesting technologies to generate power for future energy needs, providing more options than traditional sources. This review offers a comprehensive analysis of how electrospinning technology can be used in energy-autonomous wearable wireless sensing systems. It provides an overview of the electrospinning technology, fundamental mechanisms, and applications in energy scavenging, human physiological signal sensing, energy storage, and antenna for data transmission. The review discusses combining wearable electronic technology and textile engineering to create superior wearable devices and increase future collaboration opportunities. Additionally, the challenges related to conducting appropriate testing for market-ready products using these devices are also discussed.

Fabrication and characterization of lipopeptide biosurfactant-based electrospun nanofibers for use in tissue engineering

Nanofibers are a class of nanomaterial with specific physicochemical properties and characteristics making them quite sought after and investigated by researchers. Lipopeptide biosurfactant (LPB) formulation properties were previously established in wound healing. LPB were isolated from in vitro culture of Acinetobacter junii B6 and loaded on nanofibers formulation produced by electrospinning method with different ratios of carboxymethylcellulose (CMC), polyvinyl alcohol (PVA), and Poloxamer. Numerous experimental control tests were carried out on formulations, including physicochemical properties which were evaluated by using dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), morphology study by scanning electron microscopy (SEM), and thermal stability. The best nanofibers formulation was obtained by the electrospinning method, with a voltage of 19.8 volts, a discharge capacity of 1cm/h, a cylindrical rotating velocity of 100rpm, and a needle interval of 7cm from the cylinder, which continued for 7hours. The formulation contained 2% (w/v) CMC, 10% (w/v) poloxamer, 9% (w/v) PVA, and 5% (w/v) LPB. This formula had desirable physicochemical properties including spreadability, stability, and uniformity with the particle size of about 590nm.

Efficient removal of methylene blue from aqueous solution by ZIF-8-decorated helicoidal electrospun polymer strips

Immobilization of metal-organic frameworks (MOFs) on electrospun products for wastewater treatment has garnered considerable attention in recent years. However, the effect of the overall geometry and surface-area-to-volume ratio of MOF-decorated electrospun architectures on their performances have rarely been investigated. Herein, we prepared polycaprolactone (PCL)/polyvinylpyrrolidone (PVP) strips with helicoidal geometries via immersion electrospinning. By regulating the weight ratio of PCL to PVP, the morphologies and surface-area-to-volume ratios of the PCL/PVP strips could be controlled precisely. Then, the zeolitic imidazolate framework-8 (ZIF-8) for removing methylene blue (MB) from an aqueous solution was immobilized on the electrospun strips, resulting in ZIF-8-decorated PCL/PVP strips. The key characteristics of these composite products, such as adsorption and photocatalytic degradation behavior toward MB in the aqueous solution, were carefully investigated. Owing to the desired overall geometry and high surface-area-to-volume ratio of the ZIF-8-decorated helicoidal strips, a high MB adsorption capacity of 151.6 mg g^-1 was obtained, which is significantly higher than those with conventional electrospun straight fibers. In addition, higher MB uptake rates, higher recycling and kinetic adsorption efficiencies, higher MB photocatalytic degradation efficiencies, and faster MB photocatalytic degradation rates were confirmed. This work provides new insights to improve the performance of existing and potential electrospun product-based water treatment strategies.

Design, development, in-vitro and in-vivo evaluation of polylactic acid-based multifunctional nanofibrous patches for efficient healing of diabetic wounds

Impaired healing of diabetic ulcers is one of the major complications of diabetic patients due to high susceptibility to microbial infections, impaired lymphianogenesis, edema, and consequently impairing proper healing. This could even lead to much worse complications that include severe gangrene, trauma and finally limb amputation. Therefore, this study aims to develop a multilayered durable nanofibrous wound patch loaded with three promising drugs (phenytoin, sildenafil citrate and simvastatin) each in a separate layer to target a different wound healing phase. Polylactic acid was used for the preparation of the nanofibrous matrix of the wound patch, where each drug was incorporated in a separate layer during the preparation process. Drugs release profiles were studied over 3 weeks. Results showed that both phenytoin and simvastatin were released within 14 days while sildenafil continued till 21 days. Both physicochemical and mechanical characteristics of the patches were fully assessed as well as their biodegradability, swellability, breathability and porosity. Results showed that incorporation of drugs preserved the physicochemical and mechanical properties as well as porosity of the developed nanofibers. In addition, patches were evaluated for their biocompatibility and cell adhesion capability before being tested through in-vivo diabetic wound rat model induced by alloxan for three weeks. In vivo results showed that the patches were successful in inducing proper wound healing in diabetic rat model with overcoming the above-mentioned obstacles within 3 weeks. This was confirmed through assessing wound closure as well as from histopathological studies that showed complete healing with proper cell regeneration and arrangement without forming scars.

Antimicrobial and Wound-Healing Activities of Graphene-Reinforced Electrospun Chitosan/Gelatin Nanofibrous Nanocomposite Scaffolds

This study aims at preparing electrospun chitosan/gelatin nanofiber scaffolds reinforced with different amounts of graphene nanosheets to be used as antibacterial and wound-healing scaffolds. Full characterization was carried out for the different fabricated scaffolds before being assessed for their antimicrobial activity against Escherichia coli and Staphylococcus aureus, cytotoxicity, and cell migration capacity. Raman and transmission electron microscopies confirmed the successful reinforcement of nanofibers with graphene nanosheets. Scanning electron microscopy and porosity revealed that nanofibers reinforced with 0.15% graphene nanosheets produced the least diameter (106 ± 30 nm) and the highest porosity (90%), in addition to their good biodegradability and swellability. However, the excessive increase in graphene nanosheet amount produced beaded nanofibers with decreased porosity, swellability, and biodegradability. Interestingly, nanofibers reinforced with 0.15% graphene nanosheets showed E. coli and S. aureus growth inhibition percents of 50 and 80%, respectively. The cell viability assay showed no cytotoxicity on human fibroblasts when cultured with either unreinforced or reinforced nanofibers. The cell migration was higher in the case of reinforced nanofibers when compared to the unreinforced nanofibers after 24 and 48 h, which is substantially associated with the great effect of the graphene nanosheets on the cell migration capability. Unreinforced and reinforced nanofibers showed cell migration results up to 93.69 and 97%, respectively, after 48 h.

Electrospun polyacrylonitrile/hydroxyapatite composite nanofibrous membranes for the removal of lead ions from aqueous solutions

A novel Polyacrylonitrile/Hydroxyapatite (PAN/HAP) composite nanofibrous membranes were successfully prepared via the electrospinning approach. The scanning electron microscope, Fourier transforms infrared, X-ray diffraction were selected to serve as characterization techniques...

Recent update on electrospinning and electrospun nanofibers: current trends and their applications

Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made in techniques for creating electro-spun and non-electro-spun nanofibers. Nanofibers were the center of attention for industries and researchers due to their simplicity in manufacture and setup. The review discusses a thorough overview of both electrospinning and non-electrospinning processes, including their setup, fabrication process, components, and applications. The review starts with an overview of the field of nanotechnology, the background of electrospinning, the surge in demand for nanofiber production, the materials needed to make nanofibers, and the critical process variables that determine the characteristics of nanofibers. Additionally, the diverse applications of electrospun nanofibers, such as smart mats, catalytic supports, filtration membranes, energy storage/heritage components, electrical devices (batteries), and biomedical scaffolds, are then covered. Further, the review concentrates on the most recent and pertinent developments in nanofibers that are connected to the use of nanofibers, focusing on the most illustrative cases. Finally, challenges and their possible solutions, marketing, and the future prospects of nanofiber development are discussed.

Electrospinning is a versatile and viable technique for generating ultrathin fibers.

Nanofibrous tissue engineering scaffold with nonlinear elasticity created by controlled curvature and porosity

Micro-crimped fibers have been widely used in the field of tissue repair to mimic the natural tissue structure and mechanical properties. However, the electrospun nanofibrous membrane is a kind of dense structure, which cannot meet the requirements of mechanical properties and permeability. In this study, we prepared nanofibrous scaffold with controllable porosity and crimpness by sacrificing fiber components and releasing residual stress. The results show that the crimpness of the fiber is positively related to the porosity, and with the increase of porosity, the fiber crimpness increases greatly. Meanwhile, the scaffold modulus was reduced by 86% and the elongation at break doubled, which is similar to natural blood vessels. Moreover, it is found that the porous micro-crimped fiber scaffold promotes the adhesion and diffusion of endothelial cells, and facilitates the rapid endothelialization of the scaffold, which has a great potential for practical application.

Electrospun Polyacrylonitrile/Clinoptilolite Coating for SPME of PAHs from Water Samples

Electrospun polyacrylonitrile/clinoptilolite (PAN/CP) nanofibers were used to extract polycyclic aromatic hydrocarbons (PAHs) (acenaphthene, acenaphthylene, naphthalene, and phenanthrene) from water samples by solid-phase microextraction (SPME). The target PAHs was detected and quantified by gas chromatography equipped with a flame ionization detector. The PAN/CP fibrous coating with uniform morphology and without beads was electrospun after optimizing the electrospinning parameters by the Taguchi method. Thermogravimetric analysis of PAN/CP nanofibers indicated that the nanofibers are thermally stable up to 357°C. The effective parameters that affect the extraction by SPME were optimized using the response surface methodology based on the central composite design. The limits of detection and limits of quantification by the proposed method were 0.10-0.32 and 0.45-1.12 ng mL-1, respectively. The relative standard deviations were below 12%. The method was assessed for extracting PAHs from real samples including agricultural water, rainwater and spring water. The obtained relative recoveries were higher than 86%.

Tendon-bioinspired wavy nanofibrous scaffolds provide tunable anisotropy and promote tenogenesis for tendon tissue engineering

The development of tendon-biomimetic nanofibrous scaffolds with mesenchymal stem cells may represent a promising strategy to improve the unsatisfactory outcomes of traditional treatments in tendon repair. In the present study, the nanofibrous scaffolds comprised of poly(p-dioxanone) (PPDO) and silk fibroin (SF) composites were fabricated by using electrospinning technique and subsequent thermal ethanol treatment. The PPDO/SF composite scaffolds presented parallel fiber arrangement with crimped features and nonlinear mechanical properties, which mimic the structure-function relationship of native tendon tissue mechanics. We demonstrated that the fiber crimp degree and mechanical properties of as-prepared PPDO/SF wavy nanofibrous scaffolds (WNSs) could be tunable by adjusting the mass ratio of PPDO/SF. The biological tests revealed that the addition of SF obviously promoted the cell adhesion, proliferation, and phenotypic maintenance of human tenocytes on the WNSs. A preliminary study on the subcutaneous implantation showed that the PPDO/SF WNSs notably decreased the inflammatory response compared with pure PPDO WNSs. More importantly, a combination of growth factor induction and mechanical stimulation was found to notably enhance the tenogenic differentiation of human adipose derived mesenchymal stem cells on the PPDO/SF WNSs by upregulating the expressions of tendon-associated protein and gene markers. Overall, this study demonstrated that our PPDO/SF WNSs could provide a beneficial microenvironment for various cell activities, making them an attractive candidate for tendon tissue engineering research.

A review on the applications of electrospun chitosan nanofibers for the cancer treatment

In recent years, the incidence of cancer is increasing every day due to poor quality of life (industrialization of life). Therefore, the treatment of cancer has received much attention from therapists. So far, many anticancer drugs have been used to treat cancer patents. However, the direct use of the anticancer drugs has the adverse side effects for patents and several limitations to treat process. Natural chitosan nanofibers prepared by electrospinning method have unique properties such as high surface area, high porosity, suitable mechanical properties, nontoxicity, biocompatibility, biodegradability, biorenewable, low immunogenicity, better clinical functionality, analogue to extracellular model, and easy production in large scale. Therefore, this bio-polymer is a very suitable case to deliver of the anti-cancer drugs to treat cancer patents. In this review summarizes the electrospinning synthesis of chitosan and its therapeutic application for the various cancer treatment.

Electrospun Functional Nanofiber Membrane for Antibiotic Removal in Water: Review

As a new kind of water pollutant, antibiotics have encouraged researchers to develop new treatment technologies. Electrospun fiber membrane shows excellent benefits in antibiotic removal in water due to its advantages of large specific surface area, high porosity, good connectivity, easy surface modification and new functions. This review introduces the four aspects of electrospinning technology, namely, initial development history, working principle, influencing factors and process types. The preparation technologies of electrospun functional fiber membranes are then summarized. Finally, recent studies about antibiotic removal by electrospun functional fiber membrane are reviewed from three aspects, namely, adsorption, photocatalysis and biodegradation. Future research demand is also recommended.

Effects of Technical Textiles and Synthetic Nanofibers on Environmental Pollution

Textile manufacturing has been one of the highest polluting industrial sectors. It represents about one-fifth of worldwide industrial water pollution. It uses a huge number of chemicals, numerous of which are carcinogenic. The textile industry releases many harmful chemicals, such as heavy metals and formaldehyde, into water streams and soil, as well as toxic gases such as suspended particulate matter and sulphur dioxide to air. These hazardous wastes, may cause diseases and severe problems to human health such as respiratory and heart diseases. Pollution caused by the worldwide textile manufacturing units results in unimaginable harm, such as textile polymers, auxiliaries and dyes, to the environment. This review presents a systematic and comprehensive survey of all recently produced high-performance textiles; and will therefore assist a deeper understanding of technical textiles providing a bridge between manufacturer and end-user. Moreover, the achievements in advanced applications of textile material will be extensively studied. Many classes of technical textiles were proved in a variety of applications of different fields. The introductory material- and process-correlated identifications regarding raw materials and their transformation into yarns, fibers and fabrics followed by dyeing, printing, finishing of technical textiles and their further processing will be explored. Thus, the environmental impacts of technical textiles on soil, air and water are discussed.