Ultrathin Fibers Research Articles

Electrospun Polylactide-Poly(ε-Caprolactone) Fibers: Structure Characterization and Segmental Dynamic Response.

Electrospun ultrathin fibers based on binary compositions of polylactide (PLA) and poly(ε-caprolactone) (PCL) with the various content from the polymer ratio from 0/100 to 100/0 have been explored. Combining thermal (DSC) and spectropy (ESR) techniques, the effect of biopolymer content on the characteristics of the crystal structure of PLA and PCL and the rotative diffusion of the stable TEMPO radical in the intercrystallite areas of PLA/PCL compositions was shown. It was revealed that after PLA and PCL blending, significant changes in the degree of crystallinity of PLA, PCL segment mobility, sorption of the Tempo probe, as well as its activation energy of rotation in the intercrystalline areas of PLA/PCL fibers, were evaluated. The characteristic region of biopolymers' composition from 50/50 to 30/70% PLA/PCL blend ratio was found, where the inversion transition of PLA from dispersive medium to dispersive phase where an inversion transition is assumed when the continuous medium of the PLA transforms into a discrete phase. The performed studies made it possible, firstly, to carry out a detailed study of the effect of the system component ratio on the structural and dynamic characteristics of the PLA/PCL film material at the molecular level.

Confined Water Dynamics in the Scaffolds of Polylactic Acid.

Resorbable polylactic acid (PLA) ultrathin fibers have been applied as scaffolds for tissue engineering applications due to their micro- and nanoporous structure that favor cell adhesion, besides inducing cell proliferation and upregulating gene expression related to tissue regeneration. Incorporation of multiwalled carbon nanotubes into PLA fibers has been reported to increase the mechanical properties of the scaffold, making them even more suitable for tissue engineering applications. Ideally, scaffolds should be degraded simultaneously with tissue growth. Hydration and swelling are factors related to scaffold degradation. Hydration would negatively impact the mechanical properties since PLA shows hydrolytic degradation. Water absorption critically affects the catalysis and allowance of the hydrolysis reactions. Moreover, either mass transport and chemical reactions are influenced by confined water, which is an unexplored subject for PLA micro- and nanoporous fibers. Here, we probe and investigate confined water onto highly porous PLA microfibers containing few amounts of incorporated carbon nanotubes by Fourier transform infrared (FTIR) spectroscopy. A hydrostatic pressure was applied to the fibers to enhance the intermolecular interactions between water molecules and C=O groups from polyester bonds, which were evaluated over the wavenumber between 1600 and 2000 cm-1. The analysis of temperature dependence of FTIR spectra indicated the presence of confined water which is characterized by a non-Arrhenius to Arrhenius crossover at T0 = 190 K for 1716 and 1817 cm-1 carbonyl bands of PLA. These bands are sensitive to a hydrogen bond network of confined water. The relevance of our finding relies on the challenge detecting confined water in hydrophobic cavities as in the PLA one. To the best of our knowledge, we present the first report referring the presence of confined water in a hydrophobic scaffold as PLA for tissue engineering. Our findings can provide new opportunities to understand the role of confined water in tissue engineering applications. For instance, we argue that PLA degradation may be affected the most by confined water. PLA degradation involves hydrolytic and enzymatic degradation reactions, which can both be sensitive to changes in water properties.

Manufacturing 3D Biomimetic Tissue: A Strategy Involving the Integration of Electrospun Nanofibers with a 3D-Printed Framework for Enhanced Tissue Regeneration.

3D printing and electrospinning are versatile techniques employed to produce 3D structures, such as scaffolds and ultrathin fibers, facilitating the creation of a cellular microenvironment in vitro. These two approaches operate on distinct working principles and utilize different polymeric materials to generate the desired structure. This review provides an extensive overview of these techniques and their potential roles in biomedical applications. Despite their potential role in fabricating complex structures, each technique has its own limitations. Electrospun fibers may have ambiguous geometry, while 3D-printed constructs may exhibit poor resolution with limited mechanical complexity. Consequently, the integration of electrospinning and 3D-printing methods may be explored to maximize the benefits and overcome the individual limitations of these techniques. This review highlights recent advancements in combined techniques for generating structures with controlled porosities on the micro-nano scale, leading to improved mechanical structural integrity. Collectively, these techniques also allow the fabrication of nature-inspired structures, contributing to a paradigm shift in research and technology. Finally, the review concludes by examining the advantages, disadvantages, and future outlooks of existing technologies in addressing challenges and exploring potential opportunities.

Hydrophobic sorbents based on ultrathin polymer fibers for trapping oil products

Relevance. Increasing negative effects of hydrocarbon production on aquatic ecosystems and tightening of legislative norms on discharge of oil and oil product contaminated water into marine waters. Among various methods used to remove oil from aqueous solutions the most appropriate one is adsorption method. It is explained by its high degree of purification, safety, availability, manufacturability, universality of application. Synthetic materials based on ultrafine fibers have optimal characteristics for manufacturing sorbents for oil removal on their basis. However, the large-scale application of these materials is limited by their high cost, complexity of manufacturing, which excludes the secondary use of polymers as feedstock. In this regard, there is a growing need for economically and environmentally effective hydrophobic materials for sorptive treatment of aqueous media from oil and petroleum products. Aim. To determine sorption properties of hydrophobic fibrous materials produced via pneumatic formation for use as effective hydrocarbon sorbents for liquidation of oil spills in sea and water treatment on oil production platforms. Objects. Sorbents based on polypropylene and polyethylene terephthalate ultrafine fibers. Methods. Gravimetric, spectral analysis, transmission electron microscopy, gas chromatography. Results. The paper introduces the results of investigation of sorption properties of untreated ultrafine fibers obtained by pneumatic atomization and modified by microwave radiation. The authors have carried out the comparative analysis of water absorption and the influence of contact time and acidity of the medium on the degree of sorption of samples obtained from hydrophobic polymers. Promising application of sorbents based on polypropylene ultrathin fibers for oil products extraction from aqueous media was revealed. It is established that modification reduces water absorption of polypropylene sorbents and leads to an insignificant decrease in sorption properties due to changes in the supramolecular structure of polypropylene fiber samples.

Ultra-thin electrospun nanocomposite scaffold of poly (3-hydroxybutyrate)-chitosan/magnetic mesoporous bioactive glasses for bone tissue engineering applications

Bioglass is widely used in skeletal tissue engineering due to its outstanding bioactive properties. In the present study, magnetic mesoporous bioglass (MMBG) synthesized through the sol-gel method was incorporated into poly(3-hydroxybutyrate)-chitosan (PHB-Cs) solution and the resulting electrospun nanocomposite scaffolds were investigated and compared with MMBG free scaffold. The addition of 10 wt% MMBG has an outstanding effect on producing ultra-thin electrospun nanocomposite fibers due to its magnetic content (diameter of ≃128 nm). This improvement led to better mechanical properties, including an increase in both tensile modulus (up to ≃229 MPa) and tensile strength (to ≃4.95 MPa). Although the inclusion of MMBG slightly decreased the surface roughness of the nanofibrous scaffold (RMS from ≃197 to 154 nm), it could improve the wettability (WCA from ≃54 to 44°). This achievement has the potential to bring an enhancement in biomineralization and biological response. These outputs, combined with the observed increase in human osteoblast MG-63 cell viability (≃53 % improvement) as measured by MTT assay, DAPI, and SEM indicate prefer cell behavior of this nanocomposite structure. Additionally, the qualitative improvement in Alizarin Red staining and the quantitative enhancement of ALP secretion, serve as further evidence of the PHB-Cs/MMBG ultrathin nanofibers potential in bone tissue engineering.

Biocomposites Based on Electrospun Fibers of Poly(3-hydroxybutyrate) and Nanoplatelets of Graphene Oxide: Thermal Characteristics and Segmental Dynamics at Hydrothermal and Ozonation Impact.

In order to create new biodegradable nanocomposites for biomedicine, packaging, and environmentally effective adsorbents, ultra-thin composite fibers consisting of poly(3-hydroxybutyrate) (PHB) and graphene oxide (GO) were obtained by electrospinning. Comprehensive studies of ultrathin fibers combining thermal characteristics, dynamic electron paramagnetic resonance (ESR) probe measurements, and scanning electron microscopy (SEM) were carried out. It is shown that at the addition of 0.05, 0.1, 0.3, and 1% OG, the morphology and geometry of the fibers and their thermal and dynamic characteristics depend on the composite content. The features of the crystalline and amorphous structure of the PHB fibers were investigated by the ESR and DSC methods. For all compositions of PHB/GO, a nonlinear dependence of the correlation time of molecular mobility TEMPO probe (τ) and enthalpy of biopolyether melting (ΔH) is observed. The influence of external factors on the structural-dynamic properties of the composite fiber, such as hydrothermal exposure of samples in aqueous medium at 70 °C and ozonolysis, leads to extreme dependencies of τ and ΔH, which reflect two processes affecting the structure in opposite ways. The plasticizing effect of water leads to thermal destruction of the orientation of the pass-through chains in the amorphous regions of PHB and a subsequent decrease in the crystalline phase, and the aggregation of GO nanoplates into associates, reducing the number of GO-macromolecule contacts, thus increasing segmental mobility, as confirmed by decreasing τ values. The obtained PHB/GO fibrillar composites should find application in the future for the creation of new therapeutic and packaging systems with improved biocompatibility and high-barrier properties.

A Review On Electrospun Short Fiber Production

Nanotechnology has become the interest of researchers in recent years for their unique properties of submicron scale materials. Nanotechnology also consists of nanofibers made from natural or synthetic polymers which can be electrospun into ultra-thin continuous fibers. These nanofibers are versatile as it can be found in various applications such as in filtration, affinity membranes, tissue engineering, biosensors, scaffolds, drug delivery and fiber reinforcement. Over the years, many researchers have reported various methods used to produce short electrospun fiber by means of ultrasonication, mechanical cutting, UV cutting, precipitation method, microtome cutting, cryo-microcutting, cryogenic milling, ball milling, and razor blade cutting under liquid nitrogen. The aim of this paper is to provide a review on electrospun short fiber production which elaborates more on the scission methods of the continuous as-spun fibers. The literature shows that several methods have been proposed and utilized, with varying degrees of success. Overall, it can be concluded that further research is needed to fully understand the complexities of this area and to develop a more effective approach.

A Review Article: Electro-Spinning Thin Film Nano-Spun Fibers

Abstract: Electrospinning is an electron – hydrodynamic process which is gainful and flexible method. Electrospinning forms fibers in 100 NM ranges. Electrospinning mainly composed of 3 main components. High voltage, Spinners and Target collector plate. It is versatile and viable technique for ultra-thin fibers generation. Electrospinning is mainly because there is an increase in surface area compare to volume as particle get smaller. Nanotechnology accomplished most attraction by researcher a nanomaterial exhibit novel and significantly improve properties in terms of physical, chemical, biological, mechanical properties produced of electro spun nanofiber and they can be modified accordingly. Nanotechnology is a budding technology that has been identified as a vital scientific and commercial venture with global economic benefits.

Bifunctional Activated Carbon Ultrathin Fibers: Combining the Removal of VOCs and PM in One Material

Bifunctional Activated Carbon Ultrathin Fibers: Combining the Removal of VOCs and PM in One Material

Ultrathin Polymer Fibers Coated with an Amorphous SiO2–CaO–P2O5 Bioactive Powders for Biomedical Applications

Ultrathin Polymer Fibers Coated with an Amorphous SiO2–CaO–P2O5 Bioactive Powders for Biomedical Applications

NUMERICAL SIMULATION OF AN ELECTROSPINNING PROCESS USING COMSOL MULTIPHYSICS

Electrospinning is an advanced method to produce ultra-thin plastic fibers for use in tissue culture, non-woven fabrics, batteries, air filtration, water purification, and the like. This paper presents a method using numerical simulation to study the operating parameters of an electrospinning device. The software used is COMSOL Multiphysics. This commercial simulation software solution facilitates finite element analysis using differential equations (PDEs). The current study details the steps of using COMSOL Multiphysics to model an electrospinning device, which has not received enough attention in previous studies. Therefore, this study aims to provide a detailed understanding of the critical parameters governing the electrospinning process simulations, which is a crucial step toward developing an efficient electrospinning device. Moreover, this research endeavor aims to expand the usage of numerical simulations in the field of electrospinning, particularly for beginners.

Recent Advances in Electrospun Membranes for Radiative Cooling.

Radiative cooling is an approach that maximizes the thermal emission through the atmospheric window in order to dissipate heat, while minimizing the absorption of incoming atmospheric radiation, to realize a net cooling effect without consuming energy. Electrospun membranes are made of ultra-thin fibers with high porosity and surface area, which makes them suitable for radiative cooling applications. Many studies have investigated the use of electrospun membranes for radiative cooling, but a comprehensive review that summarizes the research progress in this area is still lacking. In this review, we first summarize the basic principles of radiative cooling and its significance in achieving sustainable cooling. We then introduce the concept of radiative cooling of electrospun membranes and discuss the selection criteria for materials. Furthermore, we examine recent advancements in the structural design of electrospun membranes for improved cooling performance, including optimization of geometric parameters, incorporation of highly reflective nanoparticles, and designing multilayer structure. Additionally, we discuss dual-mode temperature regulation, which aims to adapt to a wider range of temperature conditions. Finally, we provide perspectives for the development of electrospun membranes for efficient radiative cooling. This review will provide a valuable resource for researchers working in the field of radiative cooling, as well as for engineers and designers interested in commercializing and developing new applications for these materials.

Electrospinning of Potential Medical Devices (Wound Dressings, Tissue Engineering Scaffolds, Face Masks) and Their Regulatory Approach.

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.

Tungsten oxysulfide nanoparticles interspersed nylon based e-textile as a low cost, wearable multifunctional platform for ultra-sensitive tactile sensing and breath sensing applications

In this work, we report the hydrothermal synthesis of Tungsten Oxysulfide (WS2|O) nanoparticles interspersed onto porous, lightweight Nylon fabric as a clean-room-free, multifunctional sensor for detection of human breath, strain, and pressure. Morphological characterizations reveal the uniform dispersion of the conductive WS2|O nanosheets across the ultra-thin fibers of nylon. The fabricated WS2|O@nylon-based device as a breath sensor exhibits excellent sensitivity towards different breath patterns. The optimization studies resulted in a 4-layered high-performance piezoresistive wearable pressure sensor. It exhibited a sensitivity of 1.5 kPa−1, response time of 0.2 sec over a dynamic range of 50 Pa to 350 Pa. A Gauge factor of 24.2 and good mechanical stability across 10,000 cycles of compressive strain exhibited by the strain sensor makes it suitable for gesture recognition. The exceptional sensitivity, stability with good flexibility prove it as a promising device platform for the development of various wearable multifunctional sensor applications.

The Applications of Ferulic-Acid-Loaded Fibrous Films for Fruit Preservation.

The aim of this study was to develop a novel ultrathin fibrous membrane with a core-sheath structure as an antioxidant food packaging membrane. The core-sheath structure was prepared by coaxial electrospinning, and the release of active substances was regulated by its special structure. Ferulic acid (FA) was incorporated into the electrospun zein/polyethylene oxide ultrathin fibers to ensure their synergistic antioxidant properties. We found that the prepared ultrathin fibers had a good morphology and smooth surface. The internal structure of the fibers was stable, and the three materials that we used were compatible. For the different loading positions, it was observed that the core layer ferulic-acid-loaded fibers had a sustained action, while the sheath layer ferulic-acid-loaded fibers had a pre-burst action. Finally, apples were selected for packaging using fibrous membranes to simulate practical applications. The fibrous membrane was effective in reducing water loss and apple quality loss, as well as extending the shelf life. According to these experiments, the FA-loaded zein/PEO coaxial electrospinning fiber can be used as antioxidant food packaging and will also undergo more improvements in the future.

Resorbable Nanomatrices from Microbial Polyhydroxyalkanoates: Design Strategy and Characterization.

From a series of biodegradable natural polymers of polyhydroxyalkanoates (PHAs)-poly-3-hydroxybutyrate (P(3HB) and copolymers containing, in addition to 3HB monomers, monomers of 3-hydroxyvalerate (3HV), 3-hydroxyhexanoate (3HHx), and 4-hydroxybutyrate (4HB), with different ratios of monomers poured-solvent casting films and nanomembranes with oriented and non-oriented ultrathin fibers were obtained by electrostatic molding. With the use of SEM, AFM, and measurement of contact angles and energy characteristics, the surface properties and mechanical and biological properties of the polymer products were studied depending on the method of production and the composition of PHAs. It has been shown in cultures of mouse fibroblasts of the NIH 3T3 line and diploid human embryonic cells of the M22 line that elastic films and nanomembranes composed of P(3HB-co-4HB) copolymers have high biocompatibility and provide adhesion, proliferation and preservation of the high physiological activity of cells for up to 7 days. Polymer films, namely oriented and non-oriented nanomembranes coated with type 1 collagen, are positively evaluated as experimental wound dressings in experiments on laboratory animals with model and surgical skin lesions. The results of planimetric measurements of the dynamics of wound healing and analysis of histological sections showed the regeneration of model skin defects in groups of animals using experimental wound dressings from P(3HB-co-4HB) of all types, but most actively when using non-oriented nanomembranes obtained by electrospinning. The study highlights the importance of nonwoven nanomembranes obtained by electrospinning from degradable low-crystalline copolymers P(3HB-co-4HB) in the effectiveness of the skin wound healing process.

A Feature of the Crystalline and Amorphous Structure of Ultra Thin Fibers Based on Poly(3-hydroxybutyrate) (PHB) Containing Minor Concentrations of Hemin and a Complex of Tetraphenylporphyrin with Iron.

Comprehensive studies combining X-ray diffraction analysis, thermophysical, dynamic measurements by probe method and scanning electron microscopy have been carried out. The peculiarity of the crystalline and amorphous structure of ultra-thin fibers based on poly(3-hydroxybutyrate) (PHB) containing minor concentrations (0–5%) of a gene and a tetraphenylporphyrin (TFP) complex with iron (in the form of FeCl) are considered. When these complexes are added to the PHB fibers, the morphology of the fibers change: a sharp change in the crystallinity and molecular mobility in the amorphous regions of PHB is observed. When adding a gel to the fibers of PHB, a significant decrease in the degree of crystallinity, melting enthalpy, and correlation time can be observed. The reverse pattern is observed in a system with the addition of FeCl-TFP—there is a significant increase in the degree of crystallinity, melting enthalpy and correlation time. Exposure of PHB fibers with gemin in an aqueous medium at 70 °C leads to a decrease in the enthalpy of melting in modified fibers—to an increase in this parameter. The molecular mobility of chains in amorphous regions of PHB/gemin fibers increases at the same time, a nonlinear dependence of changes in molecular dynamics is observed in PHB/FeCl-TFP fibers. Ozonolysis has a complex effect on the amorphous structure of the studied systems. The obtained fibrous materials have bactericidal properties and should be used in the creation of new therapeutic systems of antibacterial and antitumor action.

Electrospun Zein/Polyoxyethylene Core-Sheath Ultrathin Fibers and Their Antibacterial Food Packaging Applications.

The purpose of this work is to develop a novel ultrathin fibrous membrane with a core-sheath structure as antibacterial food packaging film. Coaxial electrospinning was exploited to create the core-sheath structure, by which the delivery regulation of the active substance was achieved. Resveratrol (RE) and silver nanoparticles (AgNPs) were loaded into electrospun zein/polyethylene oxide ultrathin fibers to ensure a synergistic antibacterial performance. Under the assessments of a scanning electron microscope and transmission electron microscope, the ultrathin fiber was demonstrated to have a fine linear morphology, smooth surface and obvious core-sheath structure. X-ray diffraction and Fourier transform infrared analyses showed that RE and AgNPs coexisted in the ultrathin fibers and had good compatibility with the polymeric matrices. The water contact angle experiments were conducted to evaluate the hydrophilicity and hygroscopicity of the fibers. In vitro dissolution tests revealed that RE was released in a sustained manner. In the antibacterial experiments against Staphylococcus aureus and Escherichia coli, the diameters of the inhibition zone of the fiber were 8.89 ± 0.09 mm and 7.26 ± 0.10 mm, respectively. Finally, cherry tomatoes were selected as the packaging object and packed with fiber films. In a practical application, the fiber films effectively reduced the bacteria and decreased the quality loss of cherry tomatoes, thereby prolonging the fresh-keeping period of cherry tomatoes to 12 days. Following the protocols reported here, many new food packaging films can be similarly developed in the future.

Removal of polystyrene nanoplastic beads using gravity-driven membrane filtration: Mechanisms and effects of water matrices

Nanoplastics (NPs) are emerging water contaminants and the smaller particle size of NPs further hinders the remediation in the aspects of energy consumption and removal efficiency. Due to the loose structure and tunable functionalities, nanofibrous membranes, with ultrathin fibers (73.3 ± 31.9 nm), were developed for NPs removal in a gravity-driven application. With an ultralow ΔP0 of 353 Pa, greater than92 % of model polystyrene NPs (average size from 107 to 1450 nm) were removed at an average water flux of 109 Lm-2h−1. With advanced material characterization, the removal mechanisms were determined as: (1) size-exclusive membrane interception, which dominates the removal when dNPs > dpores; and (2) membrane adsorption of smaller NPs via electrostatic and hydrophobic interactions. The distinct removal mechanisms trigger different long-term performances on removal and water flux. Complex water matrices were also evaluated, where acidic condition and anionic surfactant were observed to hinder the removal. In addition, the nanofibrous membranes showed resistance towards inorganic scaling whereas organic foulants decreased the water flux by 15.6 % after 40 consecutive filtration runs. The fouled membranes can be regenerated in mild conditions with 5 % ethanol. Overall, nanofibrous membranes are effective in NPs removal with the high-removal efficiency, low-fouling tendency, and ease of regeneration.

Optically Triggering and Monitoring Single-Cell-Level Metabolism Using Ormosil-Decorated Ultrathin Fibers

The integration of biological components and artificial devices requires a bio-machine interface that can simultaneously trigger and monitor the activities in biosystems. Herein, we use an organically modified silicate (ormosil) composite coating containing a light-responsive nanocapsule and a fluorescent bioprobe for reactive oxygen species (ROS) to decorate ultrathin optical fibers, namely, ormosil-decorated ultrathin fibers (OD-UFs), and demonstrate that these OD-UFs can optically trigger and monitor the intracellular metabolism activities in living cells. The sizes and shapes of UF tips were finely controlled to match the dimension and mechanical properties of living cells. The increased elasticity of the ormosil coating of OD-UFs reduces possible mechanical damage during the cell membrane penetration. The light-responsive nanocapsule was physically absorbed on the surface of the ormosil coating and could release a stimulant to trigger the metabolism activities in cells upon the guided laser through OD-UFs. The fluorescent bioprobe was covalently linked with the ormosil matrix for monitoring the intracellular ROS generation, which was verified by the in vitro experiments on the microdroplets of a hydrogen peroxide solution. Finally, we found that the living cells could maintain most of their viability after being inserted with OD-UFs, and the intracellular metabolism activities were successfully triggered and monitored at the single-cell level. The OD-UF provides a new platform for the investigation of intracellular behaviors for drug stimulations and represents a new proof of concept for a bio-machine interface based on the optical and chemical activities of organic functional molecules.