Nanofiber Mats Research Articles

The p-diethanolaminomethylcalix[4]arene-incorporated polyacrylonitrile-based facilitated-transport-nanofiber mat for O2/N2 separation.

Separation of gases from air mixture is one of the most challenging and laborious separations due to the remarkably uniform molecular size of gas molecules. Therefore, the present study aimed to synthesize polyacrylonitrile-based nanofibers mat(NM) impregnated with p-diethanolaminomethylcalix[4]arene (PAN/p-DEAC4 NM) for the separation of two crucial gases O2 and N2. The affinity of the prepared PAN/p-DEAC4 NM for O2 was examined by optimizing the loading concentration of p-DEAC4 in the range from 5% to 20% (w/v). The results showed remarkable performance of the PAN/p-DEAC4 NM for O2/N2 separation with a superior O2/N2 selectivity of 12.75 and excellent permeance of 10.2 GPU for O2 and 0.8 GPU for N2 at 2 bar. The PAN/p-DEAC4 NM followed a facilitated transport mechanism for the separation of gases and it was revealed that the p-DEAC4 platform in the PAN NM is facilitating the transport of O2 due to its greater affinity towards O2. BET analysis revealed that the prepared NM possesses non-porous morphology with a surface area of 12.69 m2 g-1. SEM micrographs also confirmed the formation of defect-free NM. Thus, this study presents a unique perspective and direction for fabricating highly permeable nanofiber mats for O2/N2 separation.

In vitro and in vivo studies of Syzygium cumini-loaded electrospun PLGA/PMMA/collagen nanofibers for accelerating topical wound healing.

This work aims to develop plant extract-loaded electrospun nanofiber as an effective wound dressing scaffolds for topical wound healing. Electrospun nanofibers were fabricated from Syzygium cumini leaf extract (SCLE), poly(lactic-co-glycolic acid) (PLGA), poly(methyl methacrylate) (PMMA), collagen and glycine. Electrospinning conditions were optimized to allow the formation of nanosized and uniform fibers that display smooth surface. Morphology and swelling behavior of the formed nanofibers were studied. In addition, the antibacterial activity of the nanofibers against multidrug-resistant and human pathogens was assessed by agar-well diffusion. Results showed that nanofibers containing Syzygium cumini extract at concentrations of 0.5 and 1% w/v exhibited greater antibacterial activity against the tested Gram-positive (i.e., Staphylococcus aureus, Candida albicans, Candida glabrata and Bacillus cereus) and Gram-negative (i.e., Salmonella paratyphi and Escherichia coli) pathogens compared to the same concentrations of the plain extract. Furthermore, in vivo wound healing was evaluated in Wistar rats over a period of 14 days. In vivo results demonstrated that nanofiber mats containing SCLE and collagen significantly improved wound healing within two weeks, compared to the control untreated group. These findings highlight the potential of fabricated nanofibers in accelerating wound healing and management of topical acute wounds.

Poly(ε‑caprolactone) nanofibers functionalized with poultry feather hydrolysate as a novel antioxidant material

Bioactive keratin hydrolysates obtained from microbial treatment of poultry feathers were incorporated into polycaprolactone (PCL) nanofibers using the electrospinning method. The nanofiber mats were characterized by scanning electron microscopy (SEM),...

A Perspective on the Supersonic Solution Blowing: Nanofibers at the Forefront of Energy Storage and Conversion, and Environmental Remediation

Nanofibers play a crucial role in energy storage and conversion, catalysis, and environmental remediation applications. These nanomaterials, characterized by their high surface-to-volume ratio and porous structure, exhibit exceptional properties that render them ideal for various energy applications such as in fuel cells, lithium-ion batteries, supercapacitors, catalysis, and hydrogen production. This discussion outlines the historical context of electrospinning (ES), acknowledging its limitations in terms of commercial viability. Introducing the supersonic solution blowing (SSB) technique as a promising alternative, its energy-efficient process holds potential for commercial feasibility. The ES has remarkable advantages in nanofiber fabrication but faces limitations due to high operating costs. Solution blow spinning (SBS) offers speed and versatility; however, fibers have a broad distribution of diameters. SSB therefore overcomes some of the limitations of both ES and SBS techniques to produce defect-free nanofibers with smaller diameters at higher throughput rates. In this concise perspective paper, we emphasize the primary contributions of nanofibers to the development and optimization of materials used in energy applications. Drawing parallels with the prevalent ES and SBS techniques in the literature, we conclude with a discussion on the potential benefits that may arise as researchers increasingly explore this emerging and more efficient technique.

Production and characterization of a collagen-blended electrospun nanofiber matrix for arginase immobilization

Enzyme immobilization onto nanofiber matrices presents a promising avenue for various biotechnological applications.

In Situ Thermoelectric Property Characterization of Microscale Single Thermoelectric Fiber Based on Harmonic Detection

Exploring advanced thermoelectric materials, especially flexible thermoelectric fibers, is promising for wearable devices. The thermoelectric properties of these fibers are evaluated using the figure of merit ZT value. However, there is a lack of empirical research on the properties of microscale thermoelectric fibers, necessitating the development of precise measurement methods. In addition, since the properties of micro- and nanofiber materials can be affected by the microstructure, separate measurements of electrical conductivity, Seebeck coefficient, and thermal conductivity before calculating the ZT values can lead to large errors in the final calculations. In this study, Bi 2 Te 2.7 Se 0.3 thermoelectric fibers are prepared and measured by using a thermally drawn method and an in situ method, respectively. The in situ measurements are carried out using a self-developed instrument capable of measuring temperatures from room temperature up to 1,200 K, suitable for sample sizes ranging from micro- to nanoscale. The uncertainty of the measurement exhibits less than 6.36%. The results indicate that the thermal drawing process influences crystal growth, enhancing the Seebeck coefficient and reducing electrical conductivity and thermal conductivity. Moreover, the accuracy of the measurement method is verified by pure Pt wire. The integrated in situ measurement effectively reduces experimental errors due to sample differences when calculating parameters for multiple samples measured individually, and the maximum error that can be reduced is 19.5%. This research contributes a practical measurement method of thermoelectric fibers and advances the development of wearable thermoelectric devices.

Rational design of conductive metal-organic frameworks and aligned carbon nanofibers for enhancing the performance of flexible supercapacitors.

Carbonaceous materials are attractive active materials for the manufacture of flexible electrochemical double-layer capacitors (EDLCs) because of their high electrical conductivity, large surface area, and inherent resilience against deformation. However, compared to pseudocapacitors, which store electrochemical energy via faradaic redox reactions, EDLCs generally exhibit inferior energy density. One potential approach to addressing this issue is to incorporate highly porous and electrically conductive materials into carbonaceous material-based EDLCs. In this paper, we present a hybrid electrode consisting of a conductive metal-organic framework (c-MOF) with high electrical conductivity and unique porous structure combined with a mat of aligned carbon nanofibers (ACNFs). Its highly ordered structure facilitates electronic/ionic transport, increasing the areal capacitance by up to 3.9 times compared to randomly-oriented carbon nanofibers (RCNFs). An additional increase in areal capacitance (+64%) is achieved by introducing c-MOF (RCNFs: 25.4 mF cm-2; ACNFs: 98.7 mF cm-2; c-MOF/ACNF: 161.8 mF cm-2). Additionally, an ACNF mat exhibits excellent mechanical flexibility and electrochemical reliability, making it highly suitable for the assembly of freestanding flexible supercapacitors. By optimizing the electrochemical performance of c-MOF/ACNF and its suitability for utilization in flexible energy storage systems, this study presents a promising avenue for the practical implementation of c-MOF-based supercapacitors.

Novel three-dimensional fibrous covalent organic frameworks constructed via silver amalgam bridging for efficient organic dye adsorption and removal.

The construction of covalent organic frameworks (COFs) with unique structures has great significance in exploring the structure-function relationship and extending their potential applications. Fibrous COFs have demonstrated superior performance in specific application scenarios owing to the distinctive three-dimensional (3D) structure. Herein, we report a facile strategy for the fabrication of 3D COF nanofiber by exploiting silver amalgam as a bridging agent to assemble one-dimensional-extended PA-COF modules into a tubular structure. Dimensions of the obtained 3D COF nanofiber were predicted by DFT calculations, and the nanofiber was endowed with the merits of favorable uniformity and high stability. Due to the enhanced exposure of conjugatable binding sites for dye retention offered by the novel 3D architecture, the PA-COF nanofiber exhibits fast adsorption (within 5 min) and superior adsorption capacity to various organic dyes, e.g., 1717 mg g-1 for methylene blue (MB) and 978.3 mg g-1 for methyl orange (MO). Moreover, the PA-COF nanofiber shows excellent reusability in dye adsorption, which makes it a potential medium for removing dye pollutants from wastewater. This work presents an effective strategy to construct COF materials with unique architecture and potential prospects in the fields of separation and wastewater treatment.

C-entrapped Cu nanoparticles-infused polyaniline-modified cellulose nanofibers for the precise monitoring of xanthine in urine samples

Herein, we reported the fabrication of C-entrapped Cu nanoparticles-infused polyaniline-modified cellulose nanofibers (C@Cu-NPs/PCE) for the precise monitoring of xanthine from urine samples.

Parallel fabrication of silica optical microfibers and nanofibers

Parallel fabrication of silica optical microfibers and nanofibers

Tailoring the Morphological Properties of PVA Nanofibrous Mats by Manipulating Working Planes

Tailoring the Morphological Properties of PVA Nanofibrous Mats by Manipulating Working Planes

Characterization of electrospun pluronic F68/polyvinyl alcohol nanofibers composites containing titanium dioxide, silver, and cobalt nanoparticles for biomedical applications

Nanoscale drug delivery systems and biomedical sensors are witnessing huge research interests. Polymeric nanoparticles, nanofibers, liposomes, and nano-emulsion are regarded as novel sensors and drug delivery systems including the various types of wound dressings formulated by micro/nanofibers, hydrogels, hydrocolloids, films, foams, and sponges. Consequently, the electro-spun nanofibrous mats received the most attention since the drugs and nanoparticles embedded nanofibers have been recognized as the potential candidates for sensors and wound dressing applications. These composite materials have superior surface area-to-volume ratio, high nano-porosity, distinct skin extracellular matrix structure, and ease of electro-spinning, which also supports a prolonged drug release. In this study the main advantages of the nano-fibrillary network and the active substances that can be incorporated in fabricating the composite nanofibers as sensors and wound dressing materials are discussed. The promising “Pluronic F68” and polyvinyl alcohol (PVA), materials are used including nanoparticles (NPs) of titanium dioxide (TiO2), silver, and cobalt. The difficulties that arise by converting the Pluronic into nanofibers via electrospinning due to its low melting point and beads formation and the blending of this material with polyvinyl alcohol (PVA) are discussed. The electro-spinability of the pure Pluronic, PVA and their blends are evaluated. The microstructures and morphologies of the fabricated composite nanofibers and structures are characterized using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DSC), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The fabricated blended nanofibers were found to be compact and entangled having a diameter from 50 nm to 80 nm and length ranging from 1 to 3 μm. Meanwhile, the pure Pluronic produced nano-beads with an average size of 40 nm. These nanocomposites can be used in biomedical applications such as biosensors by embedding nanoparticles of TiO2, silver, and cobalt and for antibacterial treatment in woundcare dressings.

Short Review about Challenges and Advanced Solutions of Higher Performance Piezoelectric Nanofibers Mats

Piezoelectric nanofibers mats have been received an incremented interest in both research and commercial products for wide energy harvesting applications. Such nanofibers, with diameters less than one micron, can convert the mechanical excitations into electric signals with an improved efficiency according to formed internal electric dipoles along with higher surface-to-volume ratio, compared to bulky polymeric piezo-films. This paper introduces a brief review about the main challenges of piezoelectric nanofibers mats from different aspects including materials and processes. Then, the paper briefly discusses some recent solutions to overcome the challenges facing the piezoelectric polymeric nanofibers through materials additives and processes enhancement which can develop the piezosensitivity of the organic nanofibers.

Preparation and characterization of Fe-ZnO cellulose-based nanofiber mats with self-sterilizing photocatalytic activity to enhance antibacterial applications under visible light.

Bacterial infections and antibiotic resistance have posed a severe threat to public health in recent years. One emerging and promising approach to this issue is the photocatalytic sterilization of nanohybrids. By utilizing ZnO photocatalytic sterilization, the drawbacks of conventional antibacterial treatments can be efficiently addressed. This study examines the enhanced photocatalytic sterilizing effectiveness of Fe-doped ZnO nanoparticles (Fe-ZnO nanohybrids) incorporated into polymer membranes that are active in visible light. Using the co-precipitation procedure, Fe-ZnO nanohybrids (Fe x Zn100-x O) have been generated using a range of dopant ratios (x = 0, 3, 5, 7, and 10) and characterized. The ability to scavenge free radicals was assessed and the IC50 value was calculated using the DPPH test at different catalytic concentrations. PXRD patterns showed a hexagonal wurtzite structure, which indicated that the particle size of the nanohybrid decreased as the dopant concentration rose. It was demonstrated by UV-vis diffuse reflectance experiments that the band gap of the nanohybrid decreased (redshifted) with Fe doping. The photocatalytic activity under sunlight increased steadily to 87% after Fe was added as a dopant. The Fe 5%-ZnO nanohybrid exhibited the lowest IC50 value of 81.44 μg mL-1 compared to ZnO, indicating the highest radical scavenging activity and the best antimicrobial activity. The Fe 5%-ZnO nanohybrid, which is proven to have the best photocatalytic sterilization activity, was then incorporated into a cellulose acetate polymer membrane by electrospinning. Disc diffusion assay confirmed the highest antimicrobial activity of the Fe 5%-ZnO nanohybrid incorporated electrospun membrane against Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), and Candida albicans (ATCC 10231) under visible light. As a result, Fe 5%-ZnO nanofiber membranes have the potential to be employed as self-sterilizing materials in healthcare settings.

Airflow sensing and energy harvesting applications of PVDF-TPU piezoelectric nanofibers

Wind energy is one of the abundant potential power sources that can be found both indoors and outdoors. Recently, the focus has been placed on the potential of ambient energy gathering using natural airflow as a small-scale wind energy source. Here, highly piezoelastic nanofiber mats were fabricated from a pure polyvinylidene fluoride (PVDF) and PVDF-TPU (thermoplastic polyurethane) composites via the electrospinning approach. They have exceptional electrical energy harvesting and airflow sensing capabilities. The potential of these composite nanomats for piezoelectric energy harvesting was studied, depending on airflow perturbations in the surrounding environment. PVDF blended with 15 weight percent (wt.%) TPU exhibited the optimum sensitivity, clearly demonstrating the scope of these developed prototypes in the field of airflow sensing and energy harvesting technology.

Synergistic antimicrobial nanofiber membranes based on metal incorporated silica nanoparticles as advanced antimicrobial layers.

In this post-new-normal era, the public prioritizes preventive measures over curing, which is a constructive approach to staying healthy. In this study, an innovative antimicrobial membrane material has been developed, showcasing the promising potential for various applications. The metal-doped silica nanoparticles (Ag, Cu, and Co) were incorporated into a cellulose acetate (CA) polymer-based nanofiber membrane using the electrospinning technique. The metal nanoparticles were doped into a silanol network of silica nanoparticles. The fabricated membranes underwent detailed characterization using a wide range of techniques including PXRD, FTIR, Raman, SEM, TEM, TGA, and tensile testing. These analyses provided compelling evidence confirming the successful incorporation of metal-doped silica nanoparticles (Ag, Cu, and Co) into cellulose-based nanofibers. The band gap energies of the fabricated CA mats lie below 3.00 eV, confirming that they are visible light active. The trimetallic silica nanohybrid exhibited the lowest band gap energy of 2.84 eV, proving the self-sterilizing ability of the CA mats. The DPPH assay further confirmed the best radical scavenging activity by the trimetallic silica nanohybrid incorporated nanofiber mat (91.77 ± 0.88%). The antimicrobial activity was assessed by using the bacterial ATCC strains of Staphylococcus aureus, Streptococcus pneumoniae, MRSA (Methicillin-resistant Staphylococcus aureus), Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa and fungal strains; quality control samples of Trichophyton rubrum, Microsporum gypsium, and Aspergillus niger, as well as the ATCC strain of Candida albicans. The trimetallic silica nanohybrid-incorporated CA membranes demonstrated the most significant inhibition zones. The reported findings substantiate the self-sterilizing mat's viability, affordability, efficacy against a broad spectrum of microbial strains, cost-effectiveness, and biodegradability. Furthermore, the mat serves as a dual-purpose physical and biological barrier against microbes, affirming its potential impact.

Nanoscale assembly of enantiomeric supramolecular gels driven by the nature of solvents.

Understanding the key parameters that control the self-assembly process is critical to predict self-assembly modes in multi-component systems, which will lead to the development of nanofibrous materials with tuneable properties. Enantiomeric amino acid-based low-molecular-weight gelators (LMWGs) were mixed in polar (polar protic) and aromatic apolar (aromatic) solvents and compared to their individual counterparts to probe the effect of solvent polarity on the self-assembly process. Scanning electron microscopy (SEM) reveals that xerogels of individual components display hollow needles in polar protic solvents, while chiral coils are observed in aromatic solvents. In contrast, the multi-component gel displays hollow needle morphologies in both solvents, indicating similar morphologies in polar protic solvents but an entirely different nanostructure for the individual gel networks in aromatic solvents. PXRD experiments performed on the dried gels showed that the nature of the solvents plays a vital role in the co-assembly process of multi-component gels. The self-assembly modes and the gel state structure of the gels are analysed by wide-angle X-ray diffraction (WAXS) and small-angle neutron diffraction (SANS), which reveals that the mixed gel undergoes different co-assembly modes depending on the nature of the solvent systems. This study shows that different co-assembly modes can be achieved for structurally similar components by varying the solvent polarity, demonstrating the importance of solvent choice in the self-assembly process of multi-component gels.

TiO2/SiO2 spiral crimped Janus fibers engineered for stretchable ceramic membranes with high-temperature resistance.

The tensile brittleness of ceramic nanofibrous materials makes them unable to withstand the relatively large fracture strain, greatly limiting their applications in extreme environments such as high or ultra-low temperatures. Herein, highly stretchable and elastic ceramic nanofibrous membranes composed of titanium dioxide/silicon dioxide (TiO2/SiO2) bicomponent spiral crimped Janus fibers were designed and synthesized via conjugate electrospinning combined with calcination treatment. Owing to the opposite charges attached, the two fibers assembled side by side to form a Janus structure. Interestingly, radial shrinkage differences existed on the two sides of the TiO2/SiO2 composite nanofibers, constructing a helical crimp structure along the fiber axis. The special configuration effectively improves the stretchability of TiO2/SiO2 ceramic nanofibrous membranes, with up to 70.59% elongation at break, excellent resilience at 20% tensile strain and plastic deformation of only 3.48% after 100 cycles. Additionally, the relatively fluffy ceramic membranes constructed from spiral crimped Janus fibers delivered a lower thermal conductivity of 0.0317 W m-1 K-1, attributed to the increased internal still air content. This work not only reveals the attractive tensile mechanism of ceramic membranes arising from the highly curly nanofibers, but also proposes an effective strategy to make the ceramic materials withstand the complex dynamic strain in extreme temperature environments (from -196 °C to 1300 °C).

Direct synthesis of ultralight, elastic, high-temperature insulation N-doped TiO2 ceramic nanofibrous sponges via conjugate electrospinning.

The design of three-dimensional ceramic nanofibrous materials with high-temperature insulation and flame-retardant characteristics is of significant interest due to the effectively improved mechanical properties. However, achieving a pure ceramic monolith with ultra-low density, high elasticity and toughness remains a great challenge. Herein, a low-cost, scalable strategy to fabricate ultralight and mechanically robust N-doped TiO2 ceramic nanofibrous sponges with a continuous stratified structure by conjugate electrospinning is reported. Remarkably, the introduction of dopamine into the precursor nanofibers is engineered, which realizes the nitrogen doping to inhibit the TiO2 grain growth, endowing single nanofibers with a smoother, less defective surface. Besides, the self-polymerization process of dopamine allows the construction of bonding points between nanofibers and optimizes the distribution of inorganic micelles on polymer templates. Moreover, a rotating disk receiving device under different rotating speeds is designed to obtain N-doped TiO2 sponges with various interlamellar spacings, further affecting the maximum compressive deformation capacity. The resulting ceramic sponges, consisting of fluffy crosslinked nanofiber layers, possess low densities of 12-45 mg cm-3, which can quickly recover under a large strain of 80% and have only 9.2% plastic deformation after 100 compression cycles. In addition, the sponge also exhibits a temperature-invariant superelasticity at 25-800 °C and a low heat conductivity of 0.0285 W m-1 K-1, with an outstanding thermal insulation property, making it an ideal insulation material for high-temperature or harsh conditions.

Transformation of zinc acetate into ZnO nanofibers for enhanced NOx gas sensing: Cost-effective strategies and additive-free optimization

Gas sensors based on ZnO nanocomposites have been widely investigated for the detection of various gases. However, few studies have reported electrospun ZnO for NOx gases, especially NO (nitrogen monoxide), due to its high tendency for oxidation upon contact with air. The development of gas sensors that operate at temperatures below 300°C is challenging for metal oxide gas sensors, as decreasing the temperature can lead to lack of sensitivity and very long recovery times. In this study, the operating temperature was improved to 200°C while achieving a high response to a low concentration of 0.5 ppm gas, with recovery times of 572s and 105s for NO and NO2 (nitrogen dioxide), respectively. Detecting NO and NO2 at low ppm and ppb levels is a major demand and challenge for the development of metal oxide-based gas sensors, especially for health monitoring portable sensors. This study focuses on the design and performance of a NOx gas sensor based on ZnO nanofibrous material with precise structural optimization. The study optimizes the precursor for electrospinning without using any additives. The sensing materials proportion were optimized by changing the ratio of ZnAc:PVA in the precursor of electrospinning solution. Choosing ZnAc:PVA = 1.5 as the optimum precursor for synthesizing ZnO nanofibers resulted in the highest response of 27 and 16 (Ohm/Ohm) for 0.5 ppm NO and NO2, respectively, at 200°C and relative humidity of 50%. Additionally, reproducible sensors were developed, which is crucial for mass production. This remarkable sensitivity in low concentration indicates that the design of material structure and the control of zinc acetate amount in the electrospun solution has great practical applications to detect both gases.