Nanofiber Webs Research Articles

Development of reusable and long-term storable bacteria attached nanofiber mats for highly efficient removal of Cr(VI) and reactive dye from wastewater

Developing reusable, sustainable and long term storable bioremoval technologies is essential for removal of heavy metals and reactive dyes in industrial wastewater. <i>Clavibacter michiganensis</i> (<i>C. michiganensis</i>) having bioremediation property was selected for attachment, and polysulfone (PSU) was selected as the polymer matrices for the electrospinning of nanofibrous webs. For this approach, polysulfone nanofiber mats (PSU-NFMs) were produced by electrospinning, followed by attachment of bacteria onto nanofiber mats and a subsequent used in the removal of Cr(VI) and reactive dye. The efficient Cr(VI) removal with 100% yield was achieved within 24 hours (10 ppm) with bacteria attached nanofiber mats. Also, nano bio-composite mats decolorized 100% of Reactive Blue (RB, 20 ppm) within 13 h. Furthermore, the prepared bacteria attached to PSU-NFMs showed storage stability at 23 ± 2℃ and 4℃ for 30 days with efficient removal yields and PSU-NFMs found as potentially storable for keeping attached bacterial cells alive. Finally, the reusability of bacteria attached to PSU-NFMs were determined after five cycles for both pollutant and 70.3% and 51.8% of the Cr(VI) and dye removal capacities were obtained. It was expected that the bacteria attached to PSU-NFMs could be a potential application in wastewater treatment.

Fabric-like Electrospun PVAc-Graphene Nanofiber Webs as Wearable and Degradable Piezocapacitive Sensors.

Flexible piezocapacitive sensors utilizing nanomaterial-polymer composite-based nanofibrous membranes offer an attractive alternative to more traditional piezoelectric and piezoresistive wearable sensors owing to their ultralow powered nature, fast response, low hysteresis, and insensitivity to temperature change. In this work, we propose a facile method of fabricating electrospun graphene-dispersed PVAc nanofibrous membrane-based piezocapacitive sensors for applications in IoT-enabled wearables and human physiological function monitoring. A series of electrical and material characterization experiments were conducted on both the pristine and graphene-dispersed PVAc nanofibers to understand the effect of graphene addition on nanofiber morphology, dielectric response, and pressure sensing performance. Dynamic uniaxial pressure sensing performance evaluation tests were conducted on the pristine and graphene-loaded PVAc nanofibrous membrane-based sensors for understanding the effect of two-dimensional (2D) nanofiller addition on pressure sensing performance. A marked increase in the dielectric constant and pressure sensing performance was observed for graphene-loaded spin coated membrane and nanofiber webs respectively, and subsequently the micro dipole formation model was invoked to explain the nanofiller-induced dielectric constant enhancement. The robustness and reliability of the sensor have been underscored by conducting accelerated lifetime assessment experiments entailing at least 3000 cycles of periodic tactile force loading. A series of tests involving human physiological parameter monitoring were conducted to underscore the applicability of the proposed sensor for IoT-enabled personalized health care, soft robotics, and next-generation prosthetic devices. Finally, the easy degradability of the sensing elements is demonstrated to emphasize their suitability for transient electronics applications.

Fast-Disintegrating Nanofibrous Web of Pullulan/Griseofulvin-Cyclodextrin Inclusion Complexes.

Griseofulvin (GSF) is one of the most widely used antifungal suffering from low water solubility and limited bioavailability. Here, cyclodextrin (CD) derivatives of hydroxypropyl-beta-CD (HPβCD) known for its high-water solubility were used to form inclusion complexes (ICs) with GSF. Here, the molecular modeling study revealed the more efficient complex formation with 1:2 (guest:CD) stoichiometry, so ICs of GSF-HPβCD were prepared using a 1:2 molar ratio (GSF:HPβCD) and then mixed with pullulan (PULL) to generate nanofibers (NFs) using the electrospinning technique. PULL is a nontoxic water-soluble biopolymer and the ultimate PULL/GSF-HPβCD-IC NF was obtained with a defect-free fiber morphology having 805 ± 180 nm average diameter. The self-standing and flexible PULL/GSF-HPβCD-IC NF was achieved to be produced with a loading efficiency of ∼98% corresponding to ∼6.4% (w/w) of drug content. In comparison, the control sample of PULL/GSF NF was formed with a lower loading efficiency value of ∼72% which equals to ∼4.7% (w/w) of GSF content. Additionally, PULL/GSF-HPβCD-IC NF provided an enhanced aqueous solubility for GSF compared to PULL/GSF NF so a faster release profile with ∼2.5 times higher released amount was obtained due to inclusion complexation between GSF and HPβCD within the nanofibrous web. On the other hand, both nanofibrous webs rapidly disintegrated (∼2 s) in the artificial saliva medium that mimics the oral cavity environment. Briefly, PULL/GSF-HPβCD-IC NF can be a promising dosage formulation as a fast-disintegrating delivery system for antifungal oral administration owing to the improved physicochemical properties of GSF.

Tailoring the Porosity and Breathability of Nanofiber Webs with Mesh Size of the Deposition Material

Nano and micro-pores of the electrospun webs provide good moisture vapor transmission rate, while it maintains resistance to pressured air and resistance to liquid for some type of clothing. Laminating a nanofiber web to any textile structure could improve the desired resistance to air permeability with providing excellent breathability. In the present study, hydrophobic thermoplastic polyurethane (TPU) and hydrophilic poly (vinyl alcohol) (PVA) nanofiber webs were produced onto three different chromium sieve wires and then laminated to an interlining fabric and compared in means of pore size, breathability and air permeability. Mesh count of the wires affected the pore size and smallest pore size are belong to 90 mesh wire. The water vapor permeability of the samples varied between 80% and 90% as well as providing relatively low air permeability values. With increasing nanofiber amount, air permeability decreased dramatically.

Freestanding, flexible, ultrahigh-surface area carbon nanofibers by supersonic solution blowing: Promising electrodes for supercapacitors

Carbon nanofibers are of great technological interest, yet their large-scale production is still a challenge. For the first time, carbon nanofibers are obtained by supersonic solution blowing (SSB). Here, we produced freestanding, porous, flexible, ultrahigh-surface area carbon nanofiber webs in a single-step carbonization process of polyacrylonitrile (PAN) nanofibers. Specimens were additionally modified using phenolic resin, and furfuryl alcohol (FFA). The latter was intended to increase roughness and thus, gain surface area. It was found, however, that the modifications increased average diameter and reduced both surface area and pore volume, compared to the carbonized PAN nanofibers without surface modification. An additional modification, a specimen of composite nanofibers with embedded carbon black nanoparticles, was obtained with a fiber diameter of 60 nm and a surprising ultrahigh-surface area of 4026 m2/g. The surface-modified specimen, in which PAN nanofibers were dipped in furfuryl alcohol, revealed carbonized fibers with a diameter of 140 nm and a surface area of 1560 m²/g. When used as electrodes in symmetrical cells (coin cells), supercapacitance values in the 117 - 242 F/g range in aqueous electrolyte were measured, being comparable to those of commercial devices. The assembled symmetrical device based on specimen PAN-CB delivered high energy density and power output (27.2 Wh kg–1 at 0.77 kW kg–1 and 13.6 Wh kg–1 at 192.6 kW kg–1). Thus, the SSB technique can be used to obtain ultrahigh-surface area carbon nanofibers (> 4000 m2/g) as novel functional materials for freestanding energy storage devices without physical or chemical activation of the fibers being needed to achieve microporous structure. A fundamental fibrillary electrode area-diameter coefficient FEADC [measured in m2/(g nm)] is introduced to characterize the dependence of the specific capacitance of supercapacitor electrodes on carbon nanofiber characteristics.

Effective light management, stretchable and transparent nanofiber electrode via the incorporation of phosphors into composite nanofibers for wearable perovskite solar cells

The flexible transparent electrode is a crucial component of wearable photoelectric devices, and has a significant influence on the performance and development of wearable devices. Here, a phosphor/polyimide/polyurethane@silver composite nanofiber (NF) web electrode was fabricated by electrospinning and magnetron sputtering for wearable photoelectric devices. The electrode demonstrated a promising light management ability with converting ultraviolet light to visible light, high conductivity with sheet resistance of 22.1 Ω/square, and high transparency with transmittance of over 80%. Besides, the electrode possessed an excellent stretched capacity with tensile strain of over 100%, and tensile stability with the resistance increased by ∼75% after 500 stretching cycles at the tensile stain of 50%. As a result, a flexible perovskite solar cell (PSC) was assembled by using the NF web electrode, and possessed the power conversion efficiency of 3.47%, which is higher than that of PSCs based on electrodes without phosphor. Furthermore, the flexible PSCs exhibited promising mechanical stability under bending, and could serve as wearable devices. This work provides a feasible and promising method to prepare lightweight, stretchable, light management, and transparent electrodes for photoelectric devices, and may facilitate the development of wearable photoelectric devices.

Protease Immobilization in Solution-Blown Poly(ethylene oxide) Nanofibrous Nonwoven Webs

Enzyme-functionalized solution-blown nonwoven (EFSBN) fibers were produced by a single-step solution blow spinning method that utilizes high-velocity gas to simultaneously extrude the codissolved polymer–solvent–enzyme spinning solution and evaporate solvent at mild conditions to form a nanofibrous web with preserved enzyme activity. A broad concentration range of 0.6–7.4 wt % protein of subtilisin A protease from Bacillus licheniformis was successfully entrapped by poly(ethylene oxide) (PEO) during solution blow spinning nonwoven web production. The presence of enzyme protein in the solid nanofibers was detected by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Time of flight-secondary ion mass spectroscopy and laser confocal microscopy revealed the immobilized enzymes were mainly positioned inside the fibers and homogeneously distributed throughout the webs. Scanning electron microscopy showed that the fiber shape and diameter of PEO nanofibers containing enzymes were irregular compared to PEO-only nanofibers. Residual enzyme activity in the webs was measured by redissolving fibers in buffer and comparing the released enzyme activity to nonimmobilized free enzyme using a casein substrate-based assay. Immobilized protease (1.3% (w/w) protein in solid dry nanofiber webs) retained more than 90% of the free enzyme activity. Protease immobilized in solid nanofiber webs exhibited long storage stability at ambient (∼22 °C) and 4 °C temperature storage conditions, with more than 60% remaining catalytic activity after 300 days compared to the initial activity. Immobilized protease had equally good thermal stability as a stabilized liquid commercial protease, both retaining above 95% of their initial activity after treatment for 12 h at 65 °C. In contrast, the same liquid protease diluted in buffer lost activity within 2 h at that temperature. The nondusting, readily aqueous-soluble EFSBN solid materials are easy to handle and have good storage stability compared to liquid products.

Introduction a new structure made of hydroxyapatite and graphene nanoparticles incorporated into PCL/gelatine nano fibrous web as bone scaffold

The purpose of this research is to introduce and design scaffolds composed of polycaprolactone(PCL) and gelatine nanofibers containing both hydroxyapatite and graphene nanoparticles at the same time for using in bone tissue engineering. At first, optimal conditions for the production of PCL/gelatine nanofibrous webs were investigated. In the following step, hydroxyapatite and graphene nanoparticles incorporated into PCL/gelatine nanofibrous webs for comparison with PCL/gelatine nanofibrous webs without adding any particles. Morphological, mechanical and biological tests were done to analyse fabricated structures. 50%PCL/50%gelatin sample has the less fiber diameter in both group with or without adding nanoparticles of hydroxyapatite and graphene. The FTIR analyses revealed characteristic absorption bands for PCL/gelatin/hydroxyapatite/graphene nanofibrous scaffolds is still similar to that of PCL/gelatin sample. Also, blending of PCL with gelatin decreased tensile strength and increased the tensile strain. As the final result, the addition of hydroxyapatite and graphene reduces diameter of nanofiber and improves the biological and mechanical properties and has a good potential using in bone tissue engineering.

Synthesis of nanohybrid reinforced electrospun methylcellulose/ polyvinyl alcohol /polyethylene glycol nanofiber: study of material properties for possible biomedical applications

Over the past few epochs, emerging transdermal drug delivery systems (TDDSs) have gotten major devotion through incessant level of interest. The effort of this work is to understand the influence of nano-reinforcing agent on the morphology, property and its drug carrying capacity of the nanohybrid reinforced ketorolac tromethamine (KT) drug loaded electrospun nanofibrous web. In this study, cellulose nanocrystals (CNCs) extracted successfully from jute fibres (JF) and nanocollagen (NCG) was isolated from waste fish scales for the assembling of CNC-NCG reinforced MC/PVA/PEG electrospun nanofibrous bio-nanocomposites (BNCs) mat for transdermal drug delivery applications. The isolated nanoparticles (CNC & NCG) and the synthesized electrospun bio-nanocomposite were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), optical microscopy, Field emission scanning electron microscopy (FESEM).

Oxidative Stabilization and Characterization of Electrospun Polyacrylonitrile Nanofiber Web on Different Substrates

Oxidative Stabilization and Characterization of Electrospun Polyacrylonitrile Nanofiber Web on Different Substrates

Flexible Hybrid Electronics Nanofiber Electrodes with Excellent Stretchability and Highly Stable Electrical Conductivity for Smart Clothing.

In this paper, a side-by-side, dual-nozzle electrospinning process was used to prepare a flexible hybrid electronics (FHE) material with excellent stretchable properties. A highly stable electrical conductivity was also imparted to the resulting membrane electrodes using silver nanoparticles (AgNPs) and carbon-based nanomaterials of different structures. The AgNP/carbon-based nanomaterials were coated onto bicomponent polymer nanofibers (composed of polyurethane (PU) and polyvinylidene difluoride (PVDF)) on the nanofiber membrane. The FHE nanofiber electrodes were finally integrated into clothing designed to accurately measure human body sensing signals (e.g., electrocardiography (ECG) and electromyography (EMG) signals). To effectively increase the high electrical conductivity, a polymer-type dispersant (polyisobutylene-b-poly(oxyethylene)-b-polyisobutylene, a triblock copolymer) was used to effectively and stably disperse AgNPs with different particle sizes and carbon-based nanomaterials with different geometric dimensions (e.g., zero-dimensional carbon black, one-dimensional carbon nanotubes, and two-dimensional graphene) through non-covalent adsorption. Moreover, the bicomponent PVDF-PU nanofibers were immersed in a mixed dispersant of AgNPs and carbon-based nanomaterials at low concentrations, and thermal post-treatment was conducted to improve the electrical conductivity. The AgNP/graphene oxide (GO) nanofiber electrode exhibited a continuous phase with a stable material microstructure after 5000 repetitions of 50% tension-tension fatigue testing. The waveform pattern obtained from the proposed AgNP/GO nanofiber electrode was compared with those of traditional ECG and EMG electrodes. The nanofiber web electrode treated with organic/inorganic mixed dispersants and verified via tests of its electrical and fatigue properties was found to be suitable for long-term ECG and EMG monitoring, and it has excellent potential in wearable smart sensors.

Developing Electrospun Ethylcellulose Nanofibrous Webs: An Alternative Approach for Structuring Castor Oil.

The development of environment-friendly natural polymer gel-like dispersions in oil media, with functional properties, in terms of formulation design and synthesis protocol, is still a cutting-edge research area for many applications. The aim of this work was to study the manufacture of electrospun ethylcellulose (EC) nanofibrous webs and to examine their usage to thicken vegetable oils as an alternative approach. The role of concentration, molecular weight (Mw), and binary solvent systems on the electrospinnability of EC and subsequently on the rheological properties of EC nanofiber dispersions in castor oil was investigated. It was observed that, for each Mw, defect-free nanofibers were produced above a critical concentration, corresponding to about 2.5 the entanglement concentration (Ce). The average fiber diameter increased with both Mw and EC concentrations. Dielectric constant and dipole moment of binary solvent systems influenced the morphology of the EC nanofiber web. The morphology of the micro- and nanoarchitectures generated played a key role in the physical stabilization and rheological behavior of electrospun EC dispersions. The storage modulus (G') of EC dispersions was correlated with both the spinning solution concentration and average fiber diameter. Furthermore, electrospun EC nanofiber dispersions were compared with EC oleogels obtained by traditional thermogelation from thermorheological and tribological points of view. Overall, this work proposes an efficient and innovative approach to produce bio-based oleogel-like dispersions with great potential in different sectors such as pharmaceuticals, food, or lubricants.

Sound absorption characteristics of nanofibre web coated foams

Sound absorption properties of polyamide 6 (PA6) nanofibre webs and a widely used sound absorption foam coated with nanofibre webs have been investigated. Initial studies have focused on the electrospinning by using PA6 polymer to obtain uniform and bead-free nanofibres. Thereafter, nanofibres are electrospun on an absorption foam through two spinning durations of 10 h and 20 h. Thicknesses, mass per unit area values, porosities, pore sizes, and Brunauer-Emmet-Teller surface areas of the webs are determined. At characterization stage, sound absorption coefficients of pure nanofibre webs, pure foam, and foams enhanced with nanofibre webs are measured by acoustic impedance tube method. Noise reduction coefficients (NRC) are also calculated. Sound absorption coefficients at 6400 Hz are observed as 0.76 and 0.74 for nanofibre webs electrospun during 10 h and 20 h respectively. The NRC values are found as 0.189, 0.197 and 0.192 for pure foam sample and nanofibre webs electrospun during 10 h and 20 h respectively. Overall results of the study indicate that moderate mid-high frequency sound absorption and noise reduction coefficients are obtained by using the nanofibre web coated foams.

Fabrication and optimization of processing parameters of 2D/3D arrays of composite PET electrospun nanofibrous webs

Pristine and functional carbon nanofillers reinforced composite nanofibrous web of polyethylene terephthalate (PET) have been fabricated by the horizontal needle-based electrospinning technique. The nano materials are used to introduce the multi functionalities, like electrical conductivity, thermal stability and multiple adsorption sites. The nanocomposite nanofibrous webs are produced by mixing various weight percentages of 2D and 3D nanofillers in the matrix polymer solution. The micro structural morphologies, thermal stability, tensile strength of PET as well as the functional groups of nanofillers surface are optimized for making the 2D/3D assemblies multifunctional. The hybrid nanofibrous web is characterized by field emission scanning electron microscopy, thermal gravimetric analysis, universal testing machine, gel permeation chromatography and fourier transformed infrared spectrometer respectively. It has been found that the range of mean diameter of nanofibres lies between 165 nm and 272 nm due to the differential viscosity of nanofillers reinforced polymeric solution. The detailed structure-property studies are carried out on the reinforced functional PET nanofibres for various strategic applications.

A comprehensive review on removal of pollutants from wastewater through microbial nanobiotechnology -based solutions

ABSTRACT Increasing wastewater pollution owing to the briskly rising human population, rapid industrialization, and fast urbanization has necessitated highly efficient wastewater treatment technologies. Although several methods of wastewater treatments are in practice, expensiveness, use of noxious chemicals, generation of unsafe by-products, and longer time consumption restrain their use to a great extent. Over the last few decades, nanotechnological wastewater treatment approaches have received widespread recognition globally. Microbially fabricated nanoparticles reduce the utilization of reducing, capping, and stabilizing agents, and exhibit higher adsorptive and catalytic efficiency than chemically synthesized nanomaterials. The present review comprehensively summarizes the applications of microbial nanotechnology in the removal of a wide range of noxious wastewater pollutants. Moreover, prospects and challenges associated with the integration of nanotechnology with other biological treatment technologies including algal-membrane bioreactor, aerobic digestion, microbial fuel cells, and microbial nanofiber webs have also been briefly discussed.

Improving the Thermal Conductivity of Polymeric Nanofiber Web through the Incorporation of Boron Nitride Nanosheets

Improving the Thermal Conductivity of Polymeric Nanofiber Web through the Incorporation of Boron Nitride Nanosheets

Reusable Halophilic Bacteria Attached Cellulose Acetate Nanofiber Webs for Removal of Cr (VI) and Reactive Dye

Hexavalent Chromium (Cr (VI)) and Reactive Blue (RB) removal efficiencies of halotolerant Citricoccus sp. were examined for different parameters such as initial pH, contact time, temperature static/shaking, NaCl concentration, and different pollutant concentrations. In this research, Citricoccus sp. attached cellulose acetate (CA) nanofiber webs (NfW) were produced by electrospinning method to improve the removal yield even further. The Cr (VI) removal yield was calculated as 11.39 ± 0.002% for the pristine CA-NfW, whereas it was 39.19 ± 0.43% for bacteria attached CA-NfW. Therefore, the Cr (VI) removal capacities of bacteria attached CA-NfW were significantly higher than that of pristine CA-NfW. In addition, reusability tests revealed that bacteria attached CA-NfW can be used at least three successive times in decolorization and Cr (VI) removal steps. The decolorization rate of the RB and Cr (VI) removal yield was found to be 31.5 ± 0.2% and 5.63 ± 0.30%, respectively. These results are promising and therefore suggest that bacteria attached CA-NfW could be applicable for the removal of wastewater containing Cr (VI) and reactive dye due to their versatility and reusability.

Ondansetron/Cyclodextrin inclusion complex nanofibrous webs for potential orally fast-disintegrating antiemetic drug delivery

Ondansetron (ODS) is an effective antiemetic drug which suffers from limited solubility and bioavailability during oral administration due to first-pass metabolism. However, these limitations can be mitigated through inclusion complexation with cyclodextrins (CDs). In this study, we have reported the electrospinning of polymer-free, free-standing ODS/CD nanofibrous webs (NW), a promising approach for developing a fast-disintegrating delivery system of an antiemetic drug molecule. Highly water soluble hydroxypropyl-beta-cyclodextrins (HPβCD) were used as both complexation agent and electrospinning matrix. The computational study revealed that the 1/2 (drug/CD) stoichiometry was more favorable compared to 1/1. The ODS/HPβCD NW was obtained with higher loading efficiency (∼96 %) compared to the control sample of ODS/polyvinyl alcohol (PVA) NW (∼80 %). The amorphous distribution of ODS raised by complexation and the highly water-soluble nature of HPβCD resulted into faster and better release profile and quite faster disintegration property (∼2 s) in artificial saliva than polymeric ODS/PVA NW. Here, ODS/HPβCD NW was generated in the absence of a toxic solvent or chemical to enable the drug loading in an amorphous state. From all reasons above, ODS/HPβCD NW might be a promising alternative to the polymeric based systems for the purpose of fast-disintegrating oral drug delivery.

Syringeless electrospinning of PVDF/SiO2 as separator membrane for high-performance lithium-ion batteries

Lithium-ion batteries (LIBs) have attained great attention nowadays as a next-generation energy solution, but all of the current components need to be improved in order to meet the requirement for LIBs with mid-/high power density and capacity. Especially, the stretched olefin membrane as a separator should be reconsidered because it contains intrinsic limitations in pore size and electrolyte wettability, which is directly related to fast charge/discharge rate of LIBs. Electrospun non-woven nanofiber web has been considered as a promising candidate to improve Li-ion transportation. However, several features should be addressed for practical applications, such as the production rate (and cost) of the electrospun non-woven web, mechanical properties, and corresponding safety. In this paper, we present the electrospun non-woven web composed of PVDF based composite nanofiber as a separator in LIBs using syringeless electrospinning. Syringeless electrospinning can increase their production rate over at least 8 times higher than conventional electrospinning. In addition, this method is advantageous to incorporate colloidal inorganic fillers into the non-woven web, which makes it possible to increase the mechanical strength and electrolyte wettability. The LIBs with our non-woven separator shows improved electrochemical performances over that with the olefin separator.

Multi-layered nanofiber membranes: Preparation, characterization, and application in wastewater treatment

Over the last few decades, micropollutants have been found in the natural surface water, and their presence poses a series of risks to living organisms in the aquatic biotope. Nanofiber membranes have been shown as a new strategy for separating micron-size pollutants due to their tight pore size and high water permeability. Here, a high-efficient multi-layered nanofiber membrane with improved mechanical strength was prepared using the lamination technique. First, polyamide 6 (PA6), polyacrylonitrile (PAN), and polyvinylidene fluoride (PVDF) nanofibers webs were selected. Then nanofibers were laminated on support under various temperatures. Prepared membranes were characterized using SEM, contact angle, pore size, and air permeability tests. The significance of lamination condition on membrane structure was investigated experimentally and statically. The membranes were examined for the treatment of synthetic micropollutants. According to the results, PAN and PA6 nanofiber membranes exhibited high water permeability (over 3000 L/(m2hbar)) under low pressure, whereas PVDF membranes showed zero permeability. Besides, the prepared nanofiber membranes could separate micropollutants from water with up to 99.91% separation efficiency. Prepared nanofiber membranes hold great promise for practical applications in environmental remediation.