Electrospun Fibers Research Articles

Piperazine-loaded electrospun fiber mats with MIL-101(Cr, Mg) metal organic framework for CO2 capture

MIL-101(Cr, Mg) is a promising metal organic framework (MOF) considering its moisture, thermal, and chemical stabilities. Piperazine-loaded polyacrylonitrile (PAN)/MIL-101(Cr, Mg) fiber mats were fabricated with different percentages of piperazine (10%, 20%, and 30%) in the polymer solution using an electrospinning technique. The PAN/MIL-101 fiber mats exhibited improved adsorption capacity and selectivity when combined with piperazine because of the improved affinity of CO2 molecules for the basic amine sites of piperazine. PAN/MIL-101–20% was selected as an optimum fiber mat owing to its high CO2 adsorption capacity (2.48 mmol/g) and selectivity (38), which are 2.4 and 2.9 times higher than those of the fiber mat without piperazine, respectively. The stability of the PAN/MOF fiber mat in humid air and NO2 gas and the results of ten adsorption-desorption experiments showed consistent CO2 capture performance.

Aligned electrospun fibers of different diameters for improving cell migration capacity

Electrospun fibers have gained significant attention as scaffolds in skin tissue engineering due to their biomimetic properties, which resemble the fibrous extracellular matrix. The morphological characteristics of electrospun fibers play a crucial role in determining cell behavior. However, the effects of electrospun fibers’ arrangement and diameters on human skin fibroblasts (HSFs) remain elusive. Here, we revealed the impact of electrospun fiber diameters (700 nm, 2000 nm, and 3000 nm) on HSFs' proliferation, migration, and functional expression. The results demonstrated that all fibers exhibited good cytocompatibility. HSFs cultured on nanofibers (700 nm diameter) displayed a more dispersed and elongated morphology. Conversely, fibers with a diameter of 3000 nm exhibited a reduced specific surface area and lower adsorption of adhesion proteins, resulting in enhanced cell migration speed and effective migration rate. Meanwhile, the expression levels of migration-related genes and proteins were upregulated at 48 h for the 3000 nm fibers. This study demonstrated the unique role of fiber diameters in controlling the physiological functions of cells, especially decision-making and navigating migration in complex microenvironments of aligned electrospun fibers, and highlights the utility of these bioactive substitutes in skin tissue engineering applications.

Electrospun Si and Si/C Fiber Anodes for Li-Ion Batteries

Due to structural changes in silicon during lithiation/delithiation, most Li-ion battery anodes containing silicon show rapid gravimetric capacity fade upon charge/discharge cycling. Herein, we report on a new Si powder anode in the form of electrospun fibers with only poly(acrylic acid) (PAA) binder and no electrically conductive carbon. The performance of this anode was contrasted to a fiber mat composed of Si powder, PAA binder, and a small amount of carbon powder. Fiber mat electrodes were evaluated in half-cells with a Li metal counter/reference electrode. Without the addition of conductive carbon, a stable capacity of about 1500 mAh/g (normalized to the total weight of the anode) was obtained at 1C for 50 charge/discharge cycles when the areal loading of silicon was 0.30 mgSi/cm2, whereas a capacity of 800 mAh/g was obtained when the Si loading was increased to ~1.0 mgSi/cm2. On a Si weight basis, these capacities correspond to >3500 mAh/gSi. The capacities were significantly higher than those found with a slurry-cast powdered Si anode with PAA binder. There was no change in fiber anode performance (gravimetric capacity and constant capacity with cycling) when a small amount of electrically conductive carbon was added to the electrospun fiber anodes when the Si loading was ≤1.0 mgSi/cm2.

Electrospun controlled release anti-quorum sensing filter for biofouling prevention in MCE membranes

The formation of biofilm on the surface of water filtration membranes results in decreased flux through the filter and output of contaminated water despite filtration. The reduction in clean water output due to biofilm diminishes filtration efficiencies and feasibility of filtration in regions where alternatives do not exist. In this work, we sought to lower biofouling concerns through examination of anti-quorum sensing (anti-QS) molecules in P. aeruginosa (PAO1). QS plays a critical initial role in biofilm formation. Therefore, we hypothesized that disruption of this communication mechanism at the filtration surface would result in lower biofilm growth and higher water outputs. An electrospun filter coating was developed to prevent biofilm formation on the surface of filtration membranes. The filter coating was deposited by electrospinning (ES) fibers that contained a polymer blend made up of one hydrophobic (polycaprolactone, PCL) and one hydrophilic (polyethylene glycol, PEG) polymer to provide controlled release of anti-quorum sensing molecules (Urolithin A) to prevent biofilm formation for an extended filtration test. Results showed that a 3:1 PCL to PEG polymer blend coating containing Urolithin A (200 µg/mL) provided significant physical disruption as well as molecular interruption of biofilm formation as compared to the pristine membrane (83.48 % reduction). While fibers exhibited smooth morphologies prior to nanofiltration tests, the fibers became porous after 4 hr tests in areas where PEG had dissolved and released Urolithin A. The controlled release of anti-QS molecules by electrospun fibers provided a significantly improved anti-biofilm methodology, improving biovolume reduction by 26.05 % and increasing flux by 52.78 % as compared to similar technologies reported. In addition to these findings, this work demonstrated Urolithin A disruption of PAO1 motility on agar (65.29 % reduction @ 100 µg/mL) and reduction in biofilm thickness (84.15 % reduction @ 200 µg/mL) by dissolution from electrospun fibers in liquid culture.

A robust, scalable and adaptive wettability candle soot-modified fiber membrane for controllable oil–water mixtures/emulsion separation

Separation membranes with super-wettability are highly desirable for treating various oil/water contaminants. However, common fiber membranes suffer from single selectivity, poor stability and unsuitable pore structures, which cannot be easily modified to improve their separation performance in practice. Herein, an under-liquid superlyophobic fiber membrane (USFM) was prepared by a two-step approach, namely, spraying candle soot on an electrospun fiber membrane to form a rough structure and subsequently a thermal treatment step to improve stabilities. The obtained USFM-15 exhibits superamphiphilicity in air and under-liquid superlyophobicity after being pre-wetted by water and oil. With the synergy of suitable porosity and high selective wettability, the obtained membrane exhibited permeation fluxes of as high as 22,000 and 56,000 L m-2 h−1 with a separation efficiency of more than 99.5% for immiscible light/heavy oil/water mixtures. The USFM-15 also showed an excellent permeation flux for oil-in-water and water-in-oil emulsions of up to 4,000 and 20,000 L m-2 h−1, respectively. The separation efficiency of USFM-15 for emulsion was still more than 99.2% after 25 cycles. Moreover, the USFM-15 also has excellent reusability, high chemical stability and mechanical durability. The results of this study are expected to provide essential inspiration for designing, developing, and commercializing unique wetting materials.

A micro random laser of dye solution-filled tube system based on electrospun fibers

Random lasers (RLs) have good application prospects in speckle-free imaging, micro sensing and micro-nano photonic devices due to their properties such as cavityless, miniaturization and low-spatial coherence. The minimization, emission mechanism and lasing property control of RLs still need to be explored. In this paper, we present a novel micro RL system in a dye solution-filled tube, where the coherent random lasing action is facilitated by the integration of electrospun fibers and gold nanoparticles (Au NPs). The electrospun fibers serve as the scattering medium, while the Au NPs produce the local plasmon resonance effect. The interaction effect improves the photon scattering rate, makes the photons form a ring resonator in the system, and realizes the coherent RL in the tube system. The microtube RL has a very small size, a convenient preparation method and stable emission properties. It can withstand more than 2000 times pumping while maintaining a stable emission intensity. The electrospun fibers are stable and uniform in morphology, which makes it easy to achieve mass production of microtube RL. The speckle-free imaging experiment shows the RL has low spatial coherence, which indicates that it’s a good choice for micro speckle-free imaging. This work provides a convenient way to realize micro coherent RLs by electrospun fibers and could pave a way for applications in photonic devices.

Flame‐Retardant Properties and Characterization of Nylon/Tannic Acid Electrospun Fibers

Incorporating flame‐retardant compounds into polymeric composites is a key area of materials research. Halogenated flame‐retardants are most widely used; however, they are under scrutiny due to health and environmental concerns which increases interest in eco‐friendly alternatives. Tannic acid (TA) is a naturally occurring polyphenol with flame‐retardant properties. To overcome current challenges incorporating TA into polymer composites at high concentrations, nonwoven mats of nylon/TA composite nanofibers are fabricated using electrospinning. TA is incorporated at concentrations up to 50 wt% while maintaining uniform fiber morphology. Thermogravimetric analysis (TGA) shows TA within the nanofibers degrades at 230 °C and nylon degrades at 400 °C, irrespective of the initial TA concentration. Char yield increases with the concentration of TA, resulting in a maximum of 25% for fibers containing 50 wt% TA. Flame resistance is characterized using microscale combustion calorimetry (MCC) which shows composite fibers have reduced heat capacity and total heat release (THR) indicating flame resistance at ≥75 rel. wt%. Finally, ignition tests and condensed phase analysis show that TA acts as an intumescent material when embedded within the polymer matrix which produces an insulating foam‐like char under direct heat that eliminates flaming melt dripping and results in self‐extinguishing nanofibers.

Hydrogenation of Carbon Dioxide to Dimethyl Ether on CuO–ZnO/ZSM-5 Catalysts: Comparison of Powder and Electrospun Structures

The promising direct dimethyl ether (DME) production through CO2 hydrogenation was systematically analyzed in this research by synthesizing, characterizing, and testing several catalytic structures. In doing so, various combinations of precipitation and impregnation of copper- and zinc-oxides (CuO–ZnO) over a ZSM-5 zeolite structure were applied to synthesize the hybrid catalysts capable of hydrogenating carbon dioxide to methanol and dehydrating it to DME. The resulting catalytic structures, including the co-precipitated, sequentially precipitated, and sequentially impregnated CuO–ZnO/ZSM-5 catalysts, were prepared in the form of particle and electrospun fibers with distinguished chemical and structural features. They were then characterized using XRD, BET, XPS, ICP, TGA, SEM, and FIB-SEM/EDS analyses. Their catalytic performances were also tested and analyzed in light of their observed characteristics. It was observed that it is crucial to establish relatively small-size and well-distributed zeolite crystals across a hybrid catalytic structure to secure a distinguished DME selectivity and yield. This approach, along with other observed behaviors and the involved phenomena like catalyst particles and fibers, clusters of catalyst particles, or the whole catalytic bed, were analyzed and explained. In particular, the desired characteristics of a CuO–ZnO/ZSM-5 hybrid catalyst, synthesized in a single-pot processing of the precursors of all involved catalytically active elements, were found to be promising in guiding the future efforts in tailoring an efficient catalyst for this system.

Fibrous matrices facilitate pleurocidin killing of wound associated bacterial pathogens

Conventional wound infection treatments neither actively promote wound healing nor address the growing problem of antibacterial resistance. Antimicrobial peptides (AMPs) are natural defense molecules, released from host cells, which may be rapidly bactericidal, modulate host-immune responses, and/or act as endogenous mediators for wound healing. However, their routine clinical use has hitherto been hindered due to their instability in the wound environment. Here we describe an electrospun carrier system for topical application of pleurocidin, demonstrating sufficient AMP release from matrices to kill wound-associated pathogens including Acinetobacter baumannii and Pseudomonas aeruginosa. Pleurocidin can be incorporated into polyvinyl alcohol (PVA) fiber matrices, using coaxial electrospinning, without major drug loss with a peptide content of 0.7% w/w predicted sufficient to kill most wound associated species. Pleurocidin retains its activity on release from the electrospun fiber matrix and completely inhibits growth of two strains of A. baumannii (AYE; ATCC 17978) and other ESKAPE pathogens. Inhibition of P. aeruginosa strains (PAO1; NCTC 13437) is, however, matrix weight per volume dependent, with only larger/thicker matrices maintaining complete inhibition. The resulting estimation of pleurocidin release from the matrix reveals high efficiency, facilitating a greater AMP potency. Wound matrices are often applied in parallel or sequentially with the use of standard wound care with biocides, therefore the presence and effect of biocides on pleurocidin potency was tested. It was revealed that combinations displayed additive or modestly synergistic effects depending on the biocide and pathogens which should be considered during the therapy. Taken together, we show that electrospun, pleurocidin-loaded wound matrices have potential to be investigated for wound infection treatment.

Electrospinning of polylactic acid fibers reinforced with Ti3C2 for the removal of nickel ions from wastewater

Nickel ions play a crucial role as an essential micronutrient in both human beings and plants. However, the introduction and application of nickel ions augmented with industrialization, outpacing the expertise to access these materials beyond the planetary boundaries, causing nickel toxicity. Thus, the adsorptive removal of Ni2+ is earning ubiquitous significance attributed to the undesirable consequences on the ecosystem. The conceptualization of fabricating a sustainable material system, exterminating the prevailing challenges, thereby truncating the impact on the environment, and eradicating nickel ions from effluents was always a matter of substantial concern. Herein, we have fabricated PLA nano-microfibers via electrospinning technology with various Ti3C2 loading – 0.5, 1, and 3 wt%, introducing more porosity to the system to understand the applicability of these fibrous systems for Ni2+ removal. Incorporating Ti3C2Tx into the PLA matrix helps to fabricate a water-stable system further by increasing the adsorption capacity of PLA to 37.92 mg/g with 0.5 wt% Ti3C2Tx addition. The addition of Ti3C2Tx to the PLA matrix system and the surface morphology of the fabricated nanofiber composite were validated using FT-IR and SEM analysis, respectively. The biodegradable nature of the system was also explored under naturally mimicked conditions using cow dung slurry, where the 0.5 wt% loaded system demonstrated 12 % degradation within 30 days within the slurry. The induced biodegradability of the electrospun fibers, 3–17 % within 33 days, introduces an ideal and easily retrievable system for Ni2+ removal, eradicating potential hazardous effects on the ecosystem.

Cationic-porphyrin incorporated electrospun fibers for effective photo-inactivation of bacteria

Infectious diseases caused by pathogenic bacteria has always been a persistent concern to public health. The introduction of new microbial diseases or the re-emergence of previously controlled diseases worsens the situation. Antibacterial photodynamic therapy (APDT) is now gaining popularity in the scientific community due to its low susceptibility towards drug resistance, while bacteria often develop drug resistance rapidly in response to traditional antibiotic therapy. The present work explores the possibility of combining a biodegradable gelatin/polyurethane electrospun polymer scaffold (GP) with a cationic porphyrin (P1); to employ as a user-friendly photosensitizer in APDT. The membranes have been structurally characterized and the antibacterial action triggered by a visible light source has been investigated. The membrane GPP exhibited 97% and 96% inhibition against E. coli and S. aureus respectively in the presence of light.

Biosensing of arsenic by whole-cell bacterial bioreporter immobilized on polycaprolactone (PCL) electrospun fiber

ABSTRACT In recent years, heavy metals derived from several anthropogenic sources have both direct and indirect detrimental effects on the health of the environment and living organisms. Whole-cell bioreporters (WCBs) that can be used to monitor the levels of heavy metals in drinking and natural spring waters are important. In this study, whole-cell arsenic bacterial bioreporters were immobilized using polycaprolactone (PCL) electrospun fibers as the support material. The aim is to determine the properties of this immobilized bioreporter system by evaluating its performance in arsenic detection. Within the scope of the study, different growth media and fiber immobilization times were tested to determine the parameters affecting the fluorescent signals emitted by the immobilized bioreporter system in the presence of two dominant forms of arsenic, namely arsenite (As(III)) and arsenate (As(V)). In addition, the sensitivity, selectivity, response time, and shelf-life of the developed bioreporter system were evaluated. As far as the literature is concerned, this is the first study to investigate the potential of using PCL-electrospun fiber-immobilized fluorescent bacterial bioreporter for arsenic detection. This study will open new avenues in environmental arsenic monitoring.

Research on topological effect of natural small molecule and high–performance antibacterial air filtration application by electrospinning

The application of natural small molecule (NSM) in electrospun fibers is the key to achieving powerful functionality and sustainable development. However, the lack of understanding regarding the mechanism for loading NSM hinders the advancement of high–performance functional fibers. This work clarified the loading mechanism of NSM in polymer solution by comparing the different behaviors of curcumin (Cur), phloretin (PL), and tea polyphenols (TP) blended ethyl cellulose (EC) solutions. We found that TP may lead to the folding of polymer chains due to its strongest hydrogen bond, which in turn promoted the dispersion of TP along the polymer chain. Therefore, TP could achieve good electrospinnability at the highest loading capacity (16 times the Cur and 4 times the PL). Finally, chitosan was introduced into EC/TP to prepare tree–like nanofibers, achieving high–performance antibacterial air filtration. The filtration efficiency for 0.3 μm NaCl particles, pressure drop, and quality factor were 99.991 %, 85.5 Pa, and 0.1089 Pa−1, respectively. The bacteriostatic rates against Escherichia coli and Staphylococcus aureus were all 99.99 %. This work will promote the application of NSM and the developments of multifunctional electrospun fibers and high–performance air filters.

Efficient removal of U(VI) from wastewater by a sponge-like 3D porous architecture with hybrid electrospun nanofibers

Removal of uranium(VI) from nuclear wastewater is urgent due to the global nuclear energy exploitation. This study synthesized novel sponge-like 3D porous materials for enhanced uranium adsorption by combining electrospinning and fibrous freeze-shaping techniques. The materials possessed an organic–inorganic hybrid architecture based on the electrospun fibers of polyacrylonitrile (PAN) and SiO2. As a supporting material, the surface of fibrous SiO2 could be further functionalized by cyano groups via (3-cyanopropyl)triethoxysilane. All the cyano groups were turned into amidoxime (AO) groups to obtain a amidoxime-functionalized sponge (PAO/SiO2-AO) through the subsequent amidoximation process. The proposed sponge exhibited enhanced uranium adsorption performance with a high removal capacity of 367.12 mg/g, a large adsorption coefficient of 4.0 × 104 mL/g, and a high removal efficiency of 97.59%. The UO22+ adsorption kinetics perfectly conformed to the pseudo-second-order reaction. The sorbent also exhibited an excellent selectivity for UO22+ with other interfering metal ions.

Development of composite electrospun films utilizing soy protein amyloid fibrils and pullulan for food packaging applications

Electrospun films (ESF) are gaining attention for active delivery due to their biocompatibility and biodegradability. This study investigated the impact of adding soy protein amyloid fibrils (SAFs) to ESF. Functional ESF based on SAFs/pullulan were successfully fabricated, with SAFs clearly observed entangled in the electrospun fibers using fluorescence microscopy. The addition of SAFs improved the mechanical strength of the ESF threefold and increased its surface hydrophobicity from 24.8° to 49.9°. Moreover, the ESF demonstrated antibacterial properties against Escherichia coli and Staphylococcus aureus. In simulated oral disintegration tests, almost 100% of epigallocatechin gallate (EGCG) dissolved within 4 min from the ESF. In summary, the incorporation of SAFs into ESF improved their mechanical strength, hydrophobicity, and enabled them to exhibit antibacterial properties, making them promising candidates for active delivery applications in food systems. Additionally, the ESF showed efficient release of EGCG, indicating their potential for controlled release of bioactive compounds.

Electrospun nanofibers: Exploring process parameters, polymer selection, and recent applications in pharmaceuticals and drug delivery

Electrospinning is acknowledged as a versatile technique for producing polymer nanofibers. Various methods, such as template synthesis, self-assembly, phase separation, and drawing, have been employed to create nanofibers. However, due to its simplicity, adaptability, and the inherently high surface area-to-volume ratio in electrospun fibers, electrospinning has emerged as the most suitable method for nanofiber fabrication. This review delves into the mechanisms of nanofiber techniques and establishes how electrospinning overcomes the challenges presented by other nanofabrication methods. The review explores the principles of electrospinning, processing parameters, and their effects on resulting fibers. It also discusses the properties and selection of polymers used in electrospinning, highlighting various polymer types commonly employed in pharmaceutical applications. Additionally, the review covers different types of electrospinning and their configurations, discussing their impact on drug release profiles, along with their respective advantages and disadvantages. The recent applications of electrospinning in enhancing pharmaceutical outcomes are examined, addressing crucial aspects in the pharmaceutical field, such as improving dissolution rates, masking undesirable tastes, and enabling drug delivery through various systems. In summary, this article provides a comprehensive understanding of electrospinning and its pivotal role in advancing drug delivery approaches.

Multi-level structured polylactic acid electrospun fiber membrane based on green solvents for high-performance air filtration

Particle matter (PM) pollution seriously threatens public health as it can combine with viruses and heavy metals to enter the human body and cause various diseases. Electrospun polymer fiber membranes, especially biodegradable materials such as polylactic acid, have great potential in PM filtration. However, most polylactic acid fiber membranes are imbalanced between filtration efficiency and resistance. Porous and bead-like fibers offer higher filtration efficiency and are expected to address these challenges with their larger specific surface area. Nonetheless, this structure may compromise the mechanical strength of the fiber membrane, thereby affecting the stability of gas purification and separation. Additionally, the significant volatilization of solvents during solution electrospinning can result in environmental concerns. Here, we prepared a double-layer filter with beads and cracks using a green mixed solvent of N, N-dimethylacetamide and dimethyl carbonate. The difference in the volatilization rate of mixed solvents increases the roughness of the membrane surface and enhances the adsorption of PMs. The structural difference between the two layers of membranes enables graded filtration of particles, further reducing pressure drop. Moreover, the entanglement at the interfaces enhances the mechanical properties of the bilayer membrane. It is worth mentioning that the design of the double-layer membrane improves the overall hydrophobicity and has practical application potential.

Benefits of increasing surface to volume ratio for improving electrochemical performance of poly(3‐hexylthiophene): Electrospun fibers vs. films

AbstractWe report on successful preparation of conducting polymer nanofibers from regiorandom poly(3‐hexylthiophene). It is shown that the electrochemical properties of obtained structures are significantly improved in course of electrochemical doping process performed in the aqueous phase, moreover this process is accompanied with change of optical properties and water contact angle. These effects are not observed for polymer films. Moreover, doping of nanofibers results in pronounced, irreversible changes in the polymer structure – increased crystallinity due to incorporation of doping ions is confirmed by optical and X‐ray crystallographic studies. Ultimately, these changes lead to decreased resistance and improved electrochemical performance of nanofibers mat. As this effect is solely observed for nanofibers of conducting polymer, it can be ascribed to high surface to volume ratio of electrospun fibers mat. Therefore, it is shown for the first time that polythiophene electrochemical doping process effect is dependent on the format of the polymer applied, for nanofibers it can be regarded as attractive method of improving electrochemical properties of polymers.

Achieving better balance on the mechanical stability and conduction performance of sulfonated poly(ether ether ketone) proton exchange membranes through polydopamine/polyethyleneimine co-modified poly(vinylidene fluoride) nanofiber as support

In this work, the polyvinylidene fluoride (PVDF) electrospun fibers was applied as robust mechanical support and subsequently functionalized with polydopamine/polyethyleneimine (PDA/PEI) composite, then filled with sulfonated poly (ether ether ketone) (SPEEK) to obtain SPEEK-PDA/PEI@PVDF composite proton exchange membranes. The composite membranes achieved better balance on the mechanical stability and conduction performance, owing to enhanced interface interactions and compatibility between robust PVDF and conductive SPEEK. In wet conditions, the composite membrane exhibited excellent mechanically robust with tensile strength of 34 MPa and elongation at break of almost 200 %. Furthermore, the composite membranes also showed high structure and performance stability during the measurement of proton conductivity and fuel cell performances, it could hold stable proton conductivity of 48 mScm−1 (at 80 °C) and maximum power density of 58.9 mWcm−2. The durability test further confirmed the super operating stability of composite membrane, only 2.6 % reduction in open circuit voltage was observed during operated at 80 °C for 100 h.

Poly (Lactic Acid) Applications in Biomedical Engineering

Medical devices like implants are playing a pivotal role in medicine. As a polyester, Polylactic acid (PLA) and its copolymers are widely used in the medical area. They are used in several sections including cardiovascular and orthopedic devices, as well as advanced technologies of tissue engineering and drug delivery. In this paper, cardiovascular devices including applications of PLLA coating as drug delivery system and BVS material are introduced. Specifically, PLA can be used to foster scaffolds for bone tissue and cardiovascular tissue engineering. Then this paper introduces PLA applied in the form of nanoparticles and micelles in drug delivery. The special degrading process makes PLA an active drug delivery carrier. And it could also be used to produce biodegradable orthopaedic operation devices and offer the advantage of being free from taking out of the human body. Processing techniques are pivotal prerequisites of applications of medical usage, like electrospun fibers are used in cardiovascular and drug delivery applications. The paper summarizes the use of PLA material in those areas, and foresees the future for a prediction of the attractive prospect. Although the applications are faced with limitations like mechanical properties now, they still have a promising future in biomedicine.