Polymer Nanofibers Research Articles

Synthesis and characterization of new electrospun medical scaffold-based modified cellulose nanofiber and bioactive natural propolis for potential wound dressing applications.

Recently, the design of polymer nanofibers using the electrospinning process has attracted much interest. Particularly the use of natural polymers has promoted many advantages in their biomedical applications. However, the combination of multiple natural polymers remains a great challenge in terms of electrospun production and applied performance. From this perspective, the current investigation highlights the study of the preparation of electrospun nanomaterial scaffolds based on combined natural polymers for improved wound healing performance. First, we have synthesized a crosslinked polymer by reacting microcrystalline cellulose (MC) and chitosan (CS) biopolymer via the intermediate of citric acid as a crosslinking agent. Then a natural propolis biomolecule was incorporated into the polymer network. Different MC/CS blend ratios of 90/10 and 70/30 were then used and various machine parameters were optimized to obtain nanofiber scaffolds with excellent strength and structures. SEM, IR, physicochemical, mechanical, and morpho-logical characterization were then performed. SEM evaluation revealed homogeneous and bead-free nanofibrous structures, with well-defined morphology and a random deposition that could accurately mimic the extracellular matrix of native skin. The calculated average nanofiber diameters for the MC/CS blend ratios at 90/10 and 70/30 were 431.4 and 441.2 nm, respectively. The results showed that when the chitosan amount increased, larger nanofibers with narrow diameter distribution appeared. The prepared nanomaterials had a significant and close water vapor permeability of about 1735.12 and 1698.52 g per m per day for the two blend ratios of 90/10 and 70/30, respectively. The examination of swelling behavior revealed a noteworthy enhancement in hydrophilicity, a necessary attribute for improved healing efficacy. FT-IR analysis confirmed the success and the stability of the chemical crosslinking reaction between the two biopolymers before nanofiber conception. Excellent mechanical properties were acquired, based on the chitosan content. Both developed nanofiber scaffolds exhibited high tensile strength and Young's modulus values. The incorporation of 30% chitosan versus 10% results in an increase in tensile strength of 11% and 14% in Young's modulus. Therefore, we could adjust the different mechanical properties simply by varying the mixing rate of the electrospun polymers. Using epithelial HepG2 cells, viability and kinetic cell adhesion assays were assessed to obtain biological evaluation. No cytotoxicity was observed and good cytocompatibility was confirmed. Functionalized nanofiber biomaterials with different MC/CS ratios substantiated significant bactericidal effectiveness against Gram-positive and Gram-negative bacterial culture strains. The novel functional electrospun wound dressing scaffold demonstrated effective and promising biomedical performance, healing both acute and chronic wounds.

Preparation, design, and characterization of an electrospun polyurethane/calcium chloride nanocomposite scaffold with improved properties for skin tissue regeneration

The present research paper explores the potential of electrospun nanofibers in the promising field of skin tissue engineering. Specifically, we propose an advanced preparation and characterization of an electrospun Polyurethane/Calcium Chloride (PU/CaCl2) nanocomposite scaffold, devised to boost the scaffold’s physicochemical and biological properties for skin tissue regeneration. By incorporating CaCl2 into the PU matrix using an electrospinning process, we were able to fabricate a novel nanocomposite scaffold. The morphological examination through Field Emission Scanning Electron Microscope (FESEM) revealed that the fiber diameter of the PU/CaCl2 (563 ± 147 nm) scaffold was notably smaller compared to the control (784 ± 149 nm). The presence of CaCl2 in the PU matrix was corroborated by Fourier-Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). Furthermore, the PU/CaCl2 scaffold exhibited superior tensile strength (10.81 MPa) over pristine PU (Tensile −6.16 MPa, Contact angle - 109° ± 1° and Roughness - 854 ± 32 nm) and revealed enhanced wettability (72° ± 2°) and reduced surface roughness (274 ± 104 nm), as verified by Contact angle and Atomic Force Microscopy. The developed scaffold demonstrated improved anticoagulant properties, indicating its potential for successful integration within a biological environment. The improved properties of the PU/CaCl2 nanocomposite scaffold present a significant advancement in electrospun polymer nanofibers, offering a potential breakthrough in skin tissue engineering. However, additional studies are required to thoroughly evaluate the scaffold’s effectiveness in promoting cell adhesion, proliferation, and differentiation. We aim to catalyze significant advancements in the field by revealing the creation of a potent skin scaffold leveraging electrospun nanofibers. Encouraging deeper exploration into this innovative electrospun composite scaffold for skin tissue engineering, the PU/CaCl2 scaffold stands as a promising foundation for pioneering more innovative, efficient, and sustainable solutions in biomedical applications.

Reductive quenching of photosensitizer [Ru(bpy)3]2+ reveals the inhomogeneous distribution of sites in PAN polymer nanofibers for light-driven redox catalysis.

Integration of molecular photocatalysts into redox-inert polymers constitutes a path towards photocatalytically active, lightweight materials. In particular, electrospun polymer fibers hold potential due to their favorable surface-to-volume ratio and their straightforward fabrication. This study focuses on the polyacrylonitrile (PAN) fibers, into which the prototype photosensitizer (PS) ruthenium tris(bipyridine) [Ru(bpy)3]2+, has been embedded by electrospinning. Studying the interaction between the optically excited [Ru(bpy)3]2+ with a non-redox inert solvent within the nanofibers, we resolve a distribution of microenvironments, which differ by the extent to which the photosensitizer is exposed to the solvent. This results in a non-exponential decay of the complex's emission and pronounced differences in the transient absorption signals.

A novel XYZ electrospinning that orients the trajectory and collimates the electrified fluid jet of polymer nanofibers by induced electric fields.

Electrospinning is a process in which high voltage creates nanostructured fibers with random orientation from a polymer solution. A novel electrospinning instrument was designed and constructed, capable of orienting and collimating the trajectory of the electrified fluid jet. The equipment collimates and adjusts the electrified fluid jet in the X-Y directions using deflector plates connected to a variable electric field. Simultaneously, different membrane thicknesses can be selected, i.e., in the Z direction. Additionally, by programming the sinusoidal function generator to perform an X-Y sweep, Lissajous figures (LF) were obtained. SEM images obtained through XYZ electrospinning of PVC and PVDF membranes were used to determine the control achieved over the orientation distribution of the processed nanofibers and the modification of their diameter, with and without applying the electric field to the deflector plates. The nanofibers obtained from the polymeric membranes, which originated after the straight segment of the Taylor cone, did not exhibit a random trajectory and position. Instead, the collimated electrified fluid jet deposited them in a cross pattern (X-Y) on the collector-cathode plate.

Machine learning-guided morphological property prediction of 2D electrospun scaffolds: the effect of polymer chemical composition and processing parameters.

Among various methods for fabricating polymeric tissue engineering scaffolds, electrospinning stands out as a relatively simple technique widely utilized in research. Numerous studies have delved into understanding how electrospinning processing parameters and specific polymeric solutions affect the physical features of the resulting scaffolds. However, owing to the complexity of these interactions, no definitive approaches have emerged. This study introduces the use of Simplified Molecular Input Line Entry System (SMILES) encoding method to represent materials, coupled with machine learning algorithms, to model the relationships between material properties, electrospinning parameters and scaffolds' physical properties. Here, the scaffolds' fiber diameter and conductivity have been predicted for the first time using this approach. In the classification task, the voting classifier predicted the fibers diameter with a balanced accuracy score of 0.9478. In the regression task, a neural network regressor was architected to learn the relations between parameters and predict the fibers diameter with R2 = 0.723. In the case of fibers conductivity, regressor and classifier models were used for prediction, but the performance fluctuated due to the inadequate information in the published data and the collected dataset. Finally, the model prediction accuracy was validated by experimental electrospinning of a biocompatible polymer (i.e., polyvinyl alcohol and polyvinyl alcohol/polypyrrole). Field-emission scanning electron microscope (FE-SEM) images were used to measure fiber diameter. These results demonstrated the efficacy of the proposed model in predicting the polymer nanofiber diameter and reducing the parameter space prior to the scoping exercises. This data-driven model can be readily extended to the electrospinning of various biopolymers.

Recycling and repurposing of waste carbon nanofiber polymers: a critical review

Carbon nanofibers are a class of lightweight, high-performance composite materials.

Retracted: A Performance of a Nanofiber Polymer in Geotechnical Engineering Support

Retracted: A Performance of a Nanofiber Polymer in Geotechnical Engineering Support

The spectral properties and dispersion parameters of electrospun nanofibers Poly(vinyl alcohol/ Poly(acrylamide)

Electrospun nanofibers based on polyvinyl alcohol (PVA), polyacrylamide (PAAm), and a PVA-PAAm blend (50/50 wt.%) were effectively made a room temperature(RT) and a voltage of (12kV). The products were studied using Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy(FT-IR) and Ultraviolet-visible (UV–Vis) spectroscopy. The result of FESEM analysis showed that the polymer PVA, PAAm, and blend samples produced a random distribution of fine fibres at an average diameter of (214.12, 317.1, 157.65) nm with a smooth surface. In addition, the FESEM images demonstrate the fibres' suitability for use in gas sensing applications due to their branching fibres and porosity surface. XRD showed that the film polymeric of PVA, PAAm polymeric blend PVA-PAAm was seen to have a semicrystalline nature. According to the FTIR analysis, the PVA and PAAm networks in the PVA-PAAm polymer nanofibers were entangled due to the powerful hydrogen bond contact between the PAAm and PVA chains. Observed around (3473.79 and 3414) cm-1 were attributed to the N–H vibration and overlapped to O–H stretching. The spectra of the prepared films exhibit prominent absorption peaks, which are at the wavelength range (200-320) nm. PVA-PAAm polymer nanofibers decrease the energy gap from 3.70eV to 3.40eV. The Wemple-DiDomenico model was used to derive dispersion parameters such as dispersion energy, single oscillator energy, Urbach energy, the static refractive index and the moments of optical spectra the result of calculating by this model was compatible with that value calculated by the Tauc relation. While increased which qualifies them to be used in the electronic devices.

Overview of Tissue Engineering and Drug Delivery Applications of Reactive Electrospinning and Crosslinking Techniques of Polymeric Nanofibers with Highlights on Their Biocompatibility Testing and Regulatory Aspects.

Traditional electrospinning is a promising technique for fabricating nanofibers for tissue engineering and drug delivery applications. The method is highly efficient in producing nanofibers with morphology and porosity similar to the extracellular matrix. Nonetheless, and in many instances, the process has faced several limitations, including weak mechanical strength, large diameter distributions, and scaling-up difficulties of its fabricated electrospun nanofibers. The constraints of the polymer solution's intrinsic properties are primarily responsible for these limitations. Reactive electrospinning constitutes a novel and modified electrospinning techniques developed to overcome those challenges and improve the properties of the fabricated fibers intended for various biomedical applications. This review mainly addresses reactive electrospinning techniques, a relatively new approach for making in situ or post-crosslinked nanofibers. It provides an overview of and discusses the recent literature about chemical and photoreactive electrospinning, their various techniques, their biomedical applications, and FDA regulatory aspects related to their approval and marketing. Another aspect highlighted in this review is the use of crosslinking and reactive electrospinning techniques to enhance the fabricated nanofibers' physicochemical and mechanical properties and make them more biocompatible and tailored for advanced intelligent drug delivery and tissue engineering applications.

Fabrication and characterization of shikonin and sea buckthorn endowed nanoemulsion reinforcing elecrospun scaffolds for treatment of diabetic wounds

Electrospun polymeric nanofibers represent a novel class of wound dressing owing to their structural resemblance with the natural extracellular matrix within which pro and anti-apoptotic functions can be orchestrated comprehensively resulting in effective wound management especially in case of diabetic wounds. Recent epidemiological reports demonstrate the role of matrix metalloproteinases (MMPs) as a clear indicator of recalcitrant healing in diabetic wounds that can specifically ablate the growth factors and other pro-healing molecules hindering the healing process. Beguiling the anti-inflammatory, antimicrobial, anti-diabetic and MMP-9 modulatory properties of naphthoquinone pigments, shikonin has enticed interest of researchers in diabetic wound management. Poor solubility and photosensitivity demands novel delivery of this compound for better therapeutic efficacy. The study, thus, aims to develop reinforced shikonin and sea buckthorn oil loaded nanoemulsion (SS-NE) based chitosan scaffolds by incorporation of SS-NE as nanofiller in fibers. Subsequent characterization confirmed the stability and encapsulation of shikonin in prepared scaffold system. The results of burn wound model in diabetic Wistar rats (Type 2 diabetes) indicated that the micro-nanostructure of the fiber mats was able to promote wound healing by substantially downregulating the level of MMP-9 and stimulating collagen deposition and re-epithelization. The salient findings of the present study proposed that the bioenthused asymmetric wettable scaffolds can be employed as a propitious delivery system for treatment of diabetic wounds.

Electrospun Polymer Supported Cux O Nanostructures for CO2 Reduction Reaction

The reduction of carbon dioxide (CO2) to value-added products is a promising approach for mitigating the impact of CO2 emissions on the environment [1]. Copper oxide (CuO) and copper oxide (Cu2O) have been identified as effective catalysts for CO2 reduction reaction (CO2RR) due to their unique electronic properties [2]. Electrospinning is a versatile and efficient technique for the fabrication of high surface area polymer (P) nanofibers which enables a promising range of applications in energy storage and conversion [3].In this study, we investigate the synthesis of CuxO-incorporated polyacrylonitrile (PAN) and PAN/polyaniline (PANI) nanofibers via electrospinning and evaluate their performance as a catalyst for CO2RR. The CuxO/P nanofibers were characterized by various techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy.The results revealed that CuxO nanoparticles were dispersed on the surface of the polymer nanofibers. The XRD analysis confirmed the presence of crystalline CuxO nanoparticles in the nanofibers. The FTIR spectra indicated that CuxO was successfully incorporated into the polymer nanofibers without new chemical bond formation between CuxO and PAN.The catalytic performance of CuxO/P nanofibers was evaluated for CO2RR in a three-electrode electrochemical cell. The CuxO/P nanofibers showed a significantly enhanced catalytic activity for CO2RR. Moreover, the CuxO/P nanofibers showed good stability during the electrochemical CO2RR.The enhanced catalytic performance of CuxO/P nanofibers can be attributed to the unique electronic properties of CuxO nanoparticles, which can facilitate the adsorption and activation of CO2 molecules. Furthermore, the high surface area and porous structure of the polymer nanofibers provide abundant active sites for the CO2RR. The dispersion of CuxO nanoparticles on the surface of the polymer nanofibers can also enhance electron transfer and reduce charge transfer resistance during the CO2RR.In conclusion, CuxO-incorporated polymer nanofibers were successfully synthesized by electrospinning and showed excellent catalytic activity for CO2RR. The CuxO/P nanofibers exhibited high selectivity and stability for the electrochemical reduction of CO2 to useful chemicals. These findings suggest that CuxO/P nanofibers have great potential as an efficient catalyst for CO2RR and could contribute to the development of sustainable energy conversion and storage systems.[1] A. Aljabour, D. H. Apaydin, H. Coskun, F. Ozel, M. Ersoz, P. Stadler, N. S. Sariciftci, and M. Kus, ACS Applied Materials & Interfaces, 8 (46), 31695-31701 (2016).[2] R. W. Abebe, H. Zanling, Z. Pengxiang, H. Liangsheng, A. Didier, Coordination Chemistry Reviews, 454, 214340 (2022).[3] A. Aljabour, ChemistrySelect 5, 7482 (2020). Figure 1

(Invited) Monopolar and Bipolar Membranes Based on Nanofiber Electrospinning

Cation-exchange, anion-exchange, and bipolar membranes play crucial roles in a variety of electrochemical processes and devices, including chloralkali cells, electrodialysis separations for water purification, proton-exchange membrane and hydroxide-exchange membrane (alkaline) fuel cells, redox flow batteries, and processes for direct air capture of CO2. The incorporation of polymeric nanofibers into such membranes provides an attractive and tunable method of creating materials with new nano-morphologies and highly desirable properties.The impregnation of an ionomer solution into a pre-formed nonwoven porous mat of electrospun polymer fibers is a well-known method of making reinforced proton-exchange membranes. The use of simultaneous dual-fiber electrospinning or the electrospinning of polymer blends can be used to intermix/incorporate/co-locate dissimilar and incompatible polymers on the nanoscale. Although less studied in the literature, these methods offer many interesting possibilities for new membrane structures with targeted and unique transport and mechanical properties.In this review talk, the use of dual fiber and blended polymer fiber electrospinning for membrane fabrication will be presented for the following: (1) Nanofiber reinforced cation (proton) exchange membranes, (2) Electrospun NafionTM/PVDF dual fiber and single-fiber membranes for H2/Br2 redox flow batteries, (3) Composite anion exchange membranes, and (4) Bipolar membranes with a 3D nanofiber junction. Materials and methods for membrane fabrication will be described and the properties of the membranes will be discussed.

Cross-Aligned PTFE Nanofiber Reinforced Composite Membrane for PEM Fuel Cells

Polymer electrolyte membrane fuel cells (PEMFCs) have widely been considered environmental friendly alternative energy technologies due to their high energy conversion efficiency and zero emission. In the recent, the importance of performance and durability of electrolyte membrane, interfacial layer separating two electrodes, prohibiting fuel cross-over, while transporting only protons, has become much crucial for utilizing PEMFCs to the automobile applications such as fuel cell electric vehicles (FCEVs) and drones.Unfortunately, the current state membranes, mainly composed of perfluorosulfonic acid (PFSA) ionomers, have suffered from the high cost and low proton conductivity, and low dimensional stability during dynamic humidity changes during fuel cell operation. In order to deal with these issues, recently, a reinforced composite membranes (RCMs) have been developed in which a PFSA ionomer is impregnated into a porous support matrix consisted with nanofibrous polymer materials such as polytetrafluoroethylene (PTFE) due to their thermal/mechanical robustness. The PTFE based RCMs could provide enhanced mechanical stability and electrochemical performance with a reduced use of PFSA ionomer, but low impregnation of ionomers into nanosized hydrophobic PTFE networks, resulting in phase separation and irreversible creep deformation.Herein, we report a novel preparation of vertically alined PTFE aggregated fibers (PTFE AFs) as a reinforcement by using facile electrospinning hetero-polymer solutions containing PTFE nanoparticles and PEO (Polyethylene oxide) carrier polymer and subsequent thermal removal of PEO. Developed PTFE AF were effectively soaked by PFSA ionomers, and PTFE AF based RCMs delivered outstanding dimensional stability and proton conductivity compared to commercial RCMs. Furthermore, PTFE AF based RCMs used MEA exhibited exceptional single-cell performance and long-term stability. The enhanced performance was attributed to the facile proton conduction through the one dimensional channels between aligned fibers without fiber scattering, and effective suppression of volume expansion of hydrated PFSA ionomer by rectangular shaped PTFE fiber network. We believe the widespread use of novel PTFE fiber based membranes with an unique pattern in a variety of membrane applications where porous supports are used. Figure 1

Aligned Conjugated Polymer Nanofiber Networks in an Elastomer Matrix for High-Performance Printed Stretchable Electronics.

Conjugated polymer films are promising in wearable X-ray detection. However, achieving optimal film microstructure possessing good electrical and detection performance under large deformation via scalable printing remains challenging. Herein, we report bar-coated high-performance stretchable films based on a conjugated polymer P(TDPP-Se) and elastomer SEBS blend by optimizing the solution-processing conditions. The moderate preaggregation in solution and prolonged growth dynamics from a solvent mixture with limited dissolving capacity is critical to forming aligned P(TDPP-Se) chains/crystalline nanofibers in the SEBS phase with enhanced π-π stacking for charge transport and stress dissipation. The film shows a large elongation at break of >400% and high mobilities of 5.29 cm2 V-1 s-1 at 0% strain and 1.66 cm2 V-1 s-1 over 500 stretch-release cycles at 50% strain, enabling good X-ray imaging with a high sensitivity of 1501.52 μC Gyair-1 cm-2. Our work provides a morphology control strategy toward high-performance conjugated polymer film-based stretchable electronics.

Comparison of the mechanical characteristics of produced nanofibers by electrospinning process based on different collectors

Polymer nanofiber in nanofibrous membrane produced by electrospinning process can be employed in various fields such as medical engineering, environmental engineering, biotechnology, energy, tissue scaffolds, and protective clothing. In these applications, the mechanical properties of the nanofibrous membrane should be studied to get long-life durability. In the current study, nanofibers are obtained from electrospinning of polyacrylonitrile (PAN) solution in Dimethylformamide (DFM) solvent. Nanofibers are produced with disc, cylinder, wire drum, parallel bars and polygon collectors and their mechanical properties are examined and compared. For this study, a tensile testing machine with special jaws was applied. According to the Scanning Electron Microscope (SEM) images, the average diameter of the produced nanofibers ranges from 300 to 340 nm. In addition, nanofiber layers have a thickness of 0.03 mm. They were cut in the 10 × 25 mm2 size; then, the tensile test was performed. Results show that produced nanofiber layers by rotating cylinder collector have the highest ultimate strength while the disk collector results in the highest Young's modulus in produced samples.

Electrospun nanofiber membrane of dibenzo 14-crown-4-ether polyimide for efficient selective lithium recovery from discarded lithium-ion batteries

To meet the growing demand for lithium resources, it is ideal to develop a green and efficient approach for recovering lithium resources from discarded lithium-ion batteries. In this work, nanofiber membranes of 14-crown-4-ether polyimide (14C4PI) (Mn = 33 kDa) with the crown ether loading of 1.38 mmol g−1 in the main chain were fabricated by electrospinning and the structure of the nanofiber membrane was regulated by tuning the electrospinning parameters. The selectivity adsorption of 14C4PI nanofiber membrane was investigated in the simulated extract of discarded lithium-ion batteries. The results showed that the 14C4PI-12 nanofiber membrane with a high specific surface area of 41.27 m2/g and a diameter of 122.7 nm was successfully prepared under the operating conditions (polymer concentration of 12 wt%, voltage of 30 kV, flow speed of 1 mL h−1, tip-to-collector of 100 mm). The 14C4PI-12 nanofiber membrane displayed a high equilibrium adsorption capacity for Li+ (Qm = 40.17 mg g−1). The adsorption of Li+ onto the membrane was proven to be monolayer chemical adsorption confirmed by adsorption kinetics and isotherm models. The calculated equilibrium adsorption rate (EAR) was up to 70 % and the complex-ratio of crown ether in 14C4PI to Li+ was 1.46:1, whose theoretical value is 1:1. Meanwhile, the selective separation factor of Li+ to Na+, K+, Mn2+, Co2+, and Ni2+ were up to 52.3, 54.97, 48.82, 41.05 and 35.04, respectively, which were much higher than that obtained from other selective adsorption method reported in literatures. The density functional theory (DFT) calculations confirm that the superior selectivity of 14C4PI to Li+ is attributed to the higher Gibbs free energy change of 14C4PI-Li+ complexation (−113.99 kcal mol−1). To sum up, this work provides an efficient method to fabricate crown ether functional polymer nanofiber membrane for recycling lithium resources.

Influence of a Meltblown Die with a Laval Airstream Channel on the Manufacturing Process of a Polymer Fiber Based on an Orthogonal Test and Simulation Analysis.

A Laval nozzle is a device that accelerates a low-speed airstream to form a high-speed airstream. In this work, we use a Laval nozzle in the airstream channel design of a meltblown die to improve the tensile properties of the fiber in the airstream field of the meltblown die. The features of the airstream field of the meltblown die are analyzed by numerical simulation. For a given parametrization, six factors may be tuned to optimize the performance of the Laval airstream channel of the meltblown die. We thus use a five-level, six-factor orthogonal test method to optimize the airstream channel of the meltblown die to determine the various factors that influence the airstream field beneath the meltblown die. The results show that the optimized Laval meltblown die performs better than the traditional die and that the widths of the larynx and expansion segment most strongly affect the airstream velocity beneath the Laval meltblown die. Compared with a traditional die, the Laval die optimized by orthogonal testing increases the peak airstream velocity by 17.54%, average velocity by 96.81%, average temperature by 12.32%, and peak pressure by 14.61% and produces weaker turbulence intensity near the spinneret. These characteristics make the airstream beneath the die more stable and uniform and accelerate the attenuation of the fiber diameter, producing more polymer nanofibers. These results demonstrate a valuable approach to the design and optimization of meltblown dies and provide a technical reference for the production and application of the meltblown fiber production equipment.

In situ nanofibers patterned deposition based on electrostatic attraction–repulsion induction

The in situ nanofibers patterned deposition technique, enabling polymer nanofibers to be deposited into pre-designed patterns with high accuracy, have an extensive application prospects in many fields. Currently, the solutions of realizing the highly accurate patterning deposition all have shortcomings, such as simple pattern structure, inaccurate nanofibers deposition, fewer available material types, complex and expensive manufacturing processes, chemical pollution, etc. Here, in order to enable polymer nanofibers to be deposited into pre-designed patterns with comprehensive advantages including highly accurate deposition of multiple pattern structures, more available materials, economically efficient and environmentally friendly, an in-situ nanofibers patterned deposition technique(in-situ NFs-PDT) is proposed, based on the induction of attractive and repulsive forces of static electricity. This in-situ NFs-PDT is achieved by improving the collection terminal of electrospinning, which includes a pre-designed target pattern electrode, an insulating layer and a repulsive positive bottom electrode. By controlling the repulsion voltage and thickness of target pattern electrode, the amount of nanofibers deposited in the unpatterned template region can reach 0. In addition, in order to validate and demonstrate high-accuracy in-situ NFs-PDT, a sensor array that can sense the tensile deformation of the epidermal layer of human skin is successfully designed and fabricated.

In Vitro and Anti-Inflammatory Activity Evaluation Nanofibers from a Breath Mask and Filter Based on Polyurethane and Polyvinylidene Fluoride.

Nanofiber (NF) products exhibit outstanding performances in materials science, textiles, and medicine that cannot be realized using conventional technologies. However, the safety of such products is debated because of the potential health risks that nanomaterials pose and the lack of standardized guidelines for the safety evaluation of NF products. The global safety evaluations of nanomaterials have focused on evaluating the cytotoxicity of low-dimensional materials, including nanoparticles and nanotubes, based on OECD (Organization for Economic Co-operation and Development) criteria. NFs are one-dimensional materials with nanometer diameters and considerable lengths. Many fibers are applied in a densely woven web-like form, so assessing cellular penetration and fiber toxicity using the same methods is inappropriate. This study verifies the safety of the polyurethane (PU) and polyvinylidene fluoride (PVDF) polymers currently applied in filters and masks. To this end, polymer NFs were collected from each product, and the NFs were compared with reference samples using FT-IR and Raman spectroscopy. For the safety evaluation, DMSO stocks of varying concentrations of PVDF and PU NFs (at 0.5, 1, 5, and 10 μg/mL) were prepared. The cytotoxicity and inhibitory effects on nitric oxide production and protein expression obtained via Western blot were identified.

Investigation of the Defect and Intensity-Dependent Optical Limiting Performance of MnO2 Nanoparticle-Filled Polyvinylpyrrolidone Composite Nanofibers.

To enhance the optical limiting behavior triggered by nonlinear absorption (NA), wide-band gap MnO2 nanoparticles were incorporated into polyvinylpyrrolidone (PVP) polymer nanofibers at various concentrations. SEM images of the composite nanofibers showed that MnO2 nanoparticles are well entrapped in the nanofibers. With an increase in MnO2 nanofiller concentration, a widened optical band gap energy and an increased Urbach energy were observed. As the concentration of MnO2 nanofiller in PVP increased, the NA behavior became more pronounced but weakened with higher input intensity. This behavior was attributed to the filling of the localized defect states by one photon absorption (OPA). The NA mechanisms of the composite nanofibers were examined, considering their band gap energies and localized defect states. Although all of the composite nanofibers had OPA, sequential/simultaneous two photon absorption (TPA), and excited state absorption mechanisms, the higher concentration of the MnO2 nanofiller led to stronger NA behavior due to its more defective structure. The highest optical limiting behavior was observed for composite nanofibers with the highest concentration of MnO2 nanofiller. The results obtained show that these composite nanofibers with a high linear transmittance and an extended band gap energy can be used in optoelectronic applications that can operate in a wide spectral range. Furthermore, their robust NA behavior, coupled with their promising optical limiting characteristics, positions them as strong contenders for effective optical limiting applications.