Electrospun nanofiber membrane (NFM) has a high potential to be applied as a filter for produced water treatment due to its highly porous structure and great permeability. However, it faces fouling issues and has low mechanical properties, which reduces the performance and lifespan of the membrane. NFM has a low integrity and the fine mat easily detaches from the sheet. In this study, nylon 6,6 was selected as the polymer since it offers great hydrophilicity. In order to increase mechanical strength and separation performance of NFM, solvent vapor treatment was implemented where the vapor induces the fusion of fibers. The fabricated nylon 6,6 NFMs were treated with different exposure times of formic acid vapor. Results show that solvent vapor treatment helps to induce the fusion of overlapping fibers. The optimum exposure time for solvent vapor is 5 h to offer full retention of dispersed oil (100% of oil rejection), has 62% higher in tensile strength (1950 MPa) compared to untreated nylon 6,6 NFM (738 MPa), and has the final permeability closest to the untreated nylon 6,6 NFM (733 L/m2.h.bar). It also took more time to get fouled (220 min) compared to untreated NFM (160 min).
Nanofibrillated cellulose from biomass has recently gained attention owing to their biodegradable nature, low density, high mechanical properties, economic value and renewability. Although they still suffer from two major drawbacks. The first challenge is the exploration of raw materials and its application in nanocomposites production. Second one is high energy consumption regarding the mechanical fibrillation. However, pretreatments before mechanical isolation can overcome this problem. Hydrophilic nature of nano-size cellulose fibers restricts good dispersion of these materials in hydrophobic polymers and therefore, leads to lower mechanical properties. Surface modification before or after mechanical defibrillation could be a solution for this problem. Additionally, drying affects the size of nanofibers and its properties which needs to study further. This review focuses on recent developments in pretreatments, nanofibrillated cellulose production and its application in nanopaper applications, coating additives, security papers, food packaging, and surface modifications and also for first time its drying.
In the current practice, the clinical use of conventional skin substitutes such as autogenous skin grafts have shown several problems, mainly with respect to limited sources and donor site morbidity. In order to overcome these limitations, the use of smart synthetic biomaterials is tremendously diffusing as skin substitutes. Indeed, engineered skin grafts or analogues frequently play an important role in the treatment of chronic skin wounds, by supporting the regeneration of newly formed tissue, and at the same time preventing infections during the long-term treatment. In this context, natural proteins such as collagen-natively present in the skin tissue-embedded in synthetic polymers (i.e., PCL) allow the development of micro-structured matrices able to mimic the functions and to structure of the surrounding extracellular matrix. Moreover, the encapsulation of drugs, such as gentamicin sulfate, also improves the bioactivity of nanofibers, due to the efficient loading and a controlled drug release towards the site of interest. Herein, we have done a preliminary investigation on the capability of gentamicin sulfate, loaded into collagen-added nanofibers, for the controlled release in local infection treatments. Experimental studies have demonstrated that collagen added fibers can be efficaciously used to administrate gentamicin for 72 h without any toxic in vitro response, thus emerging as a valid candidate for the therapeutic treatment of infected wounds.
Lack of suitable auto/allografts has been delaying surgical interventions for the treatment of numerous disorders and has also caused a serious threat to public health. Tissue engineering could be one of the best alternatives to solve this issue. However, deficiency of oxygen supply in the wounded and implanted engineered tissues, caused by circulatory problems and insufficient angiogenesis, has been a rate-limiting step in translation of tissue-engineered grafts. To address this issue, we designed oxygen-releasing electrospun composite scaffolds, based on a previously developed hybrid polymeric matrix composed of poly(glycerol sebacate) (PGS) and poly(ε-caprolactone) (PCL). By performing ball-milling, we were able to embed a large percent of calcium peroxide (CP) nanoparticles into the PGS/PCL nanofibers able to generate oxygen. The composite scaffold exhibited a smooth fiber structure, while providing sustainable oxygen release for several days to a week, and significantly improved cell metabolic activity due to alleviation of hypoxic environment around primary bone-marrow-derived mesenchymal stem cells (BM-MSCs). Moreover, the composite scaffolds also showed good antibacterial performance. In conjunction to other improved features, such as degradation behavior, the developed scaffolds are promising biomaterials for various tissue-engineering and wound-healing applications.
Polymer composites are favorite materials for sensing applications due to their low cost and easy fabrication. In the current study, composite nanofibers consisting of polyethylene oxide (PEO), oxidized multi-walled carbon nanotubes (MWCNT) and copper oxide (CuO) nanoparticles with 1% and 3% of fillers (i.e., PEO-CuO-MWCNT: 1%, and PEO-CuO-MWCNT: 3%) were successfully developed through electrospinning for humidity sensing applications. The composite nanofibers were characterized by FTIR, XRD, SEM and EDX analysis. Firstly, they were loaded on an interdigitated electrode (IDE), and then the humidity sensing efficiency was investigated through a digital LCR meter (E4980) at different frequencies (100 Hz-1 MHz), as well as the percentage of relative humidity (RH). The results indicated that the composite nanofibers containing 1% and 3% MWCNT, combined with CuO in PEO polymer matrix, showed potent resistive and capacitive response along with high sensitivity to humidity at room temperature in an RH range of 30-90%. More specifically, the PEO-CuO-MWCNT: 1% nanocomposite displayed a resistive rapid response time within 3 s and a long recovery time of 22 s, while the PEO-CuO-MWCNT: 3% one exhibited 20 s and 11 s between the same RH range, respectively.
Magnetic nanofibers are composed of good dispersion of magnetic nanoparticles along an organic material. Magnetic nanofibers are potentially useful for composite reinforcement, bio-medical and tissue engineering. Nanofibers with the thinner diameter have to result in higher rigidity and tensile strength due to better alignments of lamellae along the fiber axis. In this study, the performance of electrospinning process was explained using response surface methodology (RSM) during fabrication of magnetic nanofibers using polyvinyl alcohol (PVA) as a shelter for (γ-Fe2O3) nanoparticles where the parameters investigated were flow rate, applied voltage, distance between needle and collector and collector rotating speed. The response variable was diameter distribution. The two parameters flow rate and applied voltage in primary evaluation were distinguished as significant factors. Central composite design was applied to optimize the variable of diameter distribution. Quadratic estimated model developed for diameter distribution indicated the optimum conditions to be flow rate of 0.25 ml/h at voltage of 45 kV while the distance and rotating speed are at 8 cm and 1500 rps respectively. The obtained model was verified successfully by the confirmation experiments.
For the first time, the fabrication of novel nanorods by the addition of polyaniline (PANI) to polyethylene oxide (PEO) and polyvinyl alcohol (PVA) polymers through electrospinning method is investigated. Field emission scanning electron microscopy observations reveal the formation of nanofibers and nanorods having diameters in the range of 26.87-139.90 nm and 64.11-122.40 nm, respectively, and lengths in the range of 542.10 nm to 1.32 μm. Photoluminescence (PL) analysis shows the presence of peaks which are characteristic of isotactic polymers (363-412, 529-691 nm), 412-529 nm for PVA/PEO and 363-691 nm for PVA/PEO/PANI. PL spectra also show peak bonding at a wavelength of 552 nm. Manufacture of nanorods by electrospinning method gives better options for controlling the diameter and length of nanorods.
Chitosan is a polycationic natural polymer which is abundant in nature. Chitosan has gained much attention as natural polymer in the biomedical field. The up to date drug delivery as well as the nanotechnology in controlled release of drugs from chitosan nanofibers are focused in this review. Electrospinning is one of the most established and widely used techniques for preparing nanofibers. This method is versatile and efficient for the production of continuous nanofibers. The chitosan-based nanofibers are emerging materials in the arena of biomaterials. Recent studies revealed that various drugs such as antibiotics, chemotherapeutic agents, proteins and anti-inflammatory analgesic drugs were successfully loaded onto electrospun nanofibers. Chitosan nanofibers have several outstanding properties for different significant pharmaceutical applications such as wound dressing, tissue engineering, enzyme immobilization, and drug delivery systems. This review highlights different issues of chitosan nanofibers in drug delivery applications, starting from the preparation of chitosan nanofibers, followed by giving an idea about the biocompatibility and degradation of chitosan nanofibers, then describing how to load the drug into the nanofibers. Finally, the major applications of chitosan nanofibers in drug delivery systems.
Separation and purification of oilfield produced water (OPW) is a major environmental challenge due to the co-production of the OPW during petroleum exploration and production operations. Effective capture of oil contaminant and its in-situ photodegradation is one of the promising methods to purify the OPW. Based on the photocatalytic capability of graphitic carbon nitride (GCN) which was recently rediscovered, photodegradation capability of GCN for OPW was investigated in this study. GCN was synthesized by calcination of urea and further exfoliated into nanosheets. The GCNs were incorporated into polyacrylonitrile nanofibers using electrospinning, which gave a liquid-permeable self-supporting photocatalytic nanofiber mat that can be handled by hand. The photocatalytic nanofiber demonstrated 85.4% degradation of OPW under visible light irradiation, and improved the degradation to 96.6% under UV light. Effective photodegradation of the photocatalytic nanofiber for OPW originates from synergetic effects of oil adsorption by PAN nanofibers and oil photodegradation by GCNs. This study provides an insight for industrial application on purification of OPW through photocatalytic degradation under solar irradiation.
A novel third generation H2O2 biosensor is fabricated using multiporous SnO2 nanofiber/carbon nanotubes (CNTs) composite as a matrix for the immobilization of redox protein onto glassy carbon electrode. The multiporous nanofiber (MPNFs) of SnO2 is synthesized by electrospinning technique from the tin precursor. This nanofiber shows high surface area and good electrical conductivity. The SnO2 nanofiber/CNT composite increases the efficiency of biomolecule loading due to its high surface area. The morphology of the nanofiber has been evaluated by scanning electron microscopy (SEM). Cyclic Voltammetry and amperometry technique are employed to study and optimize the performance of the fabricated electrode. A direct electron transfer between the protein's redox centre and the glassy carbon electrode is established after fabrication of the electrode. The fabricated electrode shows excellent electrocatalytic reduction to H2O2. The catalysis currents increases linearly to the H2O2 concentration in a wide range of 1.0 10-6-1.4×10-4M and the lowest detection limit was 30nM (S/N=3). Moreover, the biosensor showed a rapid response to H2O2, a good stability and reproducibility.
This work reports on a novel glucose biosensor based on co-immobilization of glucose oxidase (GOx) and horseradish peroxidase with polymerized multiporous nanofiber (MPNFs) of SnO2 onto glassy carbon electrode with chitosan. Multiporous nanofibers of SnO2 were synthesized by electrospinning method from the tin precursor which possesses high surface area good electrical conductivity, and the nanofibers were polymerized with polyaniline (PANI). GOx and HRP were then co-immobilized with the nanofibers on the surface of the glassy carbon electrode by using chitosan. The polymerized nanofibers play a significant role in facilitating the direct electron transfer between the electroactive center of the immobilized enzyme and the electrode surface. The morphology of the nanofiber and polymerized nanofiber has been evaluated by field emission scanning electron microscopy (FESEM). Cyclic Voltammetry and amperometry were employed to study and optimize the performance of the fabricated biosensor. The PANI/SnO2-NF/GOx-HRP/Ch/GC biosensor displayed a linear amperometric response towards the glucose concentration range from 5 to 100 μM with a detection limit of 1.8 μM (S/N = 3). Also, the anti-interference study and real sample analysis was investigated. Furthermore, the biosensor reported in this work exhibited excellent stability, reproducibility, and repeatability.
Demand is increasing for superhydrophobic materials in many applications, such as membrane distillation, separation and special coating technologies. In this study, we report a chemical vapor deposition (CVD) process to fabricate superhydrophobic carbon nanomaterials (CNM) on nickel (Ni)-doped powder activated carbon (PAC). The reaction temperature, reaction time and H2/C2H2 gas ratio were optimized to achieve the optimum contact angle (CA) and carbon yield (CY). For the highest CY (380%) and CA (177°), the optimal reaction temperatures were 702 °C and 687 °C, respectively. However, both the reaction time (40 min) and gas ratio (1.0) were found to have similar effects on CY and CA. Based on the Field emission scanning electron microscopy and transmission electron microscopy images, the CNM could be categorized into two main groups: a) carbon spheres (CS) free carbon nanofibers (CNFs) and b) CS mixed with CNFs, which were formed at 650 and 750 °C, respectively. Raman spectroscopy and thermogravimetric analysis also support this finding. The hydrophobicity of the CNM, expressed by the CA, follows the trend of CS-mixed CNFs (CA: 177°) > CS-free CNFs (CA: 167°) > PAC/Ni (CA: 65°). This paves the way for future applications of synthesized CNM to fabricate water-repellent industrial-grade technologies.
Polyethylene oxide (PEO)/chitosan (CS)/graphene oxide (GO) electrospun nanofibrous scaffolds were successfully developed via electrospinning process for controlled release of doxorubicin (DOX). The SEM analysis of nanofibrous scaffolds with different contents of GO (0.1, 0.2, 0.5 and 0.7wt.%) indicated that the minimum diameter of nanofibers was found to be 85nm for PEO/CS/GO 0.5% nanofibers. The π-π stacking interaction between DOX and GO with fine pores of nanofibrous scaffolds exhibited higher drug loading (98%) and controlled release of the DOX loaded PEO/CS/GO nanofibers. The results of DOX release from nanofibrous scaffolds at pH5.3 and 7.4 indicated strong pH dependence. The hydrogen bonding interaction between GO and DOX could be unstable under acidic conditions which resulted in faster drug release rate in pH5.3. The cell viability results indicated that DOX loaded PEO/CS/GO/DOX nanofibrous scaffold could be used as an alternative source of DOX compared with free DOX to avoid the side effects of free DOX. Thus, the prepared nanofibrous scaffold offers as a novel formulation for treatment of lung cancer.
Superhydrophilic graphene oxide/electrospun cellulose nanofibre (GO/CNF) was synthesized, characterized and successfully used in a solid-phase membrane tip adsorption (SPMTA) as an adsorbent towards a simultaneous analysis of polar organophosphorus pesticides (OPPs) in several food and water samples. Separation, determination and quantification were achieved prior to ultra-performance liquid chromatography coupled with ultraviolet detector. The influence of several parameters such as sample pH, adsorption time, adsorbent dosage and initial concentration were investigated. SPMTA was linear in the range of 0.05 and 10 mg l-1 under the optimum adsorption conditions (sample pH 12; 5 mg of adsorbent dosage; 15 min of adsorption time) for methyl parathion, ethoprophos, sulfotepp and chlorpyrifos with excellent correlation coefficients of 0.994-0.999. Acceptable precision (RSDs) as achieved for intraday (0.06-5.44%, n = 3) and interday (0.17-7.76%, n = 3) analyses. Low limits of detection (0.01-0.05 mg l-1) and satisfactory consistency in adsorption (71.14-99.95%) were obtained for the spiked OPPs from Sungai Pahang, Tasik Cheras, cabbages and rice samples. The adsorption data were well followed the second-order kinetic model and fits the Freundlich adsorption model. The newly synthesized GO/CNF showed a great adsorbent potential for OPPs analysis.
In this study, single, mix, multilayer Polyvinyl alcohol (PVA) electrospun nanofibers with epidermal growth factor (EGF) and fibroblast growth factor (FGF) were fabricated and characterized as a biological wound dressing scaffolds. The biological activities of the synthesized scaffolds have been verified by in vitro and in vivo studies. The chemical composition finding showed that the identified functional units within the produced nanofibers (O-H and N-H bonds) are attributed to both growth factors (GFs) in the PVA nanofiber membranes. Electrospun nanofibers' morphological features showed long protrusion and smooth morphology without beads and sprayed with an average range of 198-286 nm fiber diameter. The fiber diameters decrement and the improvement in wettability and surface roughness were recorded after GFs incorporated within the PVA Nanofibers, which indicated potential good adoption as biological dressing scaffolds due to the identified mechanical properties (Young's modulus) in between 18 and 20 MPa. The MTT assay indicated that the growth factor release from the PVA nanofibers has stimulated cell proliferation and promoted cell viability. In the cell attachment study, the GFs incorporated PVA nanofibers stimulated cell proliferation and adhered better than the PVA control sample and presented no cytotoxic effect. The in vivo studies showed that compared to the control and single PVA-GFs nanofiber, the mix and multilayer scaffolds gave a much more wound reduction at day 7 with better wound repair at day 14-21, which indicated to enhancing tissue regeneration, thus, could be a projected as a suitable burn wound dressing scaffold.
The conventional isolation of cellulose nanofibers (CNFs) process involves high energy input which leads to compromising the pulp fiber's physical and chemical properties, in addition to the issue of elemental chlorine-based bleaching, which is associated with serious environmental issues. This study investigates the characteristic functional properties of CNFs extracted via total chlorine-free (TCF) bleached kenaf fiber followed by an eco-friendly supercritical carbon dioxide (SC-CO2) treatment process. The Fourier transmission infra-red FTIR spectra result gave remarkable effective delignification of the kenaf fiber as the treatment progressed. TEM images showed that the extracted CNFs have a diameter in the range of 10-15 nm and length of up to several micrometers, and thereby proved that the supercritical carbon dioxide pretreatment followed by mild acid hydrolysis is an efficient technique to extract CNFs from the plant biomass. XRD analysis revealed that crystallinity of the fiber was enhanced after each treatment and the obtained crystallinity index of the raw fiber, alkali treated fiber, bleached fiber, and cellulose nanofiber were 33.2%, 54.6%, 88.4%, and 92.8% respectively. SEM images showed that amorphous portions like hemicellulose and lignin were removed completely after the alkali and bleaching treatment, respectively. Moreover, we fabricated a series of cellulose nanopapers using the extracted CNFs suspension via a simple vacuum filtration technique. The fabricated cellulose nanopaper exhibited a good tensile strength of 75.7 MPa at 2.45% strain.
Skin and soft tissue infections are major concerns with respect to wound repair. Recently, anti-bacterial wound dressings have been emerging as promising candidates to reduce infection, thus accelerating the wound healing process. This paper presents our work to develop and characterize poly(vinyl alcohol) (PVA)/chitosan (CS)/silk sericin (SS)/tetracycline (TCN) porous nanofibers, with diameters varying from 305 to 425 nm, both in vitro and in vivo for potential applications as wound dressings. The fabricated nanofibers possess a considerable capacity to take up water through swelling (~325-650%). Sericin addition leads to increased hydrophilicity and elongation at break while decreasing fiber diameter and mechanical strength. Moreover, fibroblasts (L929) cultured on the nanofibers with low sericin content (PVA/CS/1-2SS) displayed greater proliferation compared to those on nanofibers without sericin (PVA/CS). Nanofibers loaded with high sericin and tetracycline content significantly inhibited the growth of Escherichia coli and Staphylococcus aureus. In vivo examination revealed that PVA/CS/2SS-TCN nanofibers enhance wound healing, re-epithelialization, and collagen deposition compared to traditional gauze and nanofibers without sericin. The results of this study demonstrate that the PVA/CS/2SS-TCN nanofiber creates a promising alternative to traditional wound dressing materials.
In this data article, we provide energy dispersive X-ray spectroscopy (EDX) spectra of the electrospun composite (SnO2-TiO2) nanowires with the elemental values measured in atomic and weight%. The linear sweep voltammetry data of composite and its component nanofibers are provided. The data collected in this article is directly related to our research article "Synergistic combination of electronic and electrical properties of SnO2 and TiO2 in a single SnO2-TiO2 composite nanowire for dye-sensitized solar cells" [1].
This study aimed to explore a potential use of fish scale-derived gelatin nanofibrous scaffolds (GNS) in tissue engineering due to their biological and economical merits. Extraction of gelatin was achieved via decalcification, sonication and lyophilization of mixed fish scales. To fabricate nano-scale architecture of scaffolds analogous to natural extracellular matrix, gelatin was rendered into nanofibrous matrices through 6-h electrospinning, resulting in the average diameter of 48 ± 12 nm. In order to improve the water-resistant ability while retaining their biocompatibility, GNS were physically crosslinked with ultraviolet (UV) irradiation for 5 min (UGN5), 10 min (UGN10) and 20 min (UGN20). On average, the diameter of nanofibers increased by 3 folds after crosslinking, however, Fourier transform infrared spectroscopy analysis confirmed that no major alterations occurred in the functional groups of gelatin. A degradation assay showed that UGN5 and UGN10 scaffolds remained in minimum essential medium for 14 days, while UGN20 scaffolds degraded completely after 10 days. All UGN scaffolds promoted adhesion and proliferation of human keratinocytes, HaCaT, without causing an apparent cytotoxicity. UGN5 scaffolds were shown to stimulate a better growth of HaCaT cells compared to other scaffolds upon 1 day of incubation, whereas UGN20 had a long-term effect on cells exhibiting 25% higher cell proliferation than positive control after 7 days. In the wound scratch assay, UGN5 scaffolds induced a rapid cell migration closing up to 79% of an artificial wound within 24 h. The current findings provide a new insight of UGN scaffolds to serve as wound dressings in the future. In the wound scratch assay, UGN5 induced a rapid cell migration closing up to 79% of an artificial wound within 24 h.
Novel bio-based polyurethane (PU) nanocomposites composed of cellulose nanofiller extracted from the rachis of date palm tree and polycaprolactone (PCL) diol based PU were prepared by casting/evaporation. Two types of nanofiber were used: cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs). The mechanical and thermal properties of the nanocomposite films were studied by DMA, DSC, and tensile tests and the morphology was investigated by SEM. Bionanocomposites presented good mechanical properties in comparison to neat PU. While comparing both nanofillers, the improvement in mechanical and thermal properties was more pronounced for the nanocomposites based on CNF which could be explained, not only by the higher aspect ratio of CNF, but also by their better dispersion in the PU matrix. Calculation of the solubility parameters of the nanofiller surface polymers and of the PU segments portend a better interfacial adhesion for CNF based nanocomposites compared to CNC.