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.
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.
The lack of aesthetic properties of electrospun nanofibres in terms of colour appearance is the drive in this preliminary study. This research is conducted to study the dyeing behaviour and colorimetric properties of electrospun nanofibres blended with Remazol Yellow FG reactive dye using dope-dyeing method via electrospinning process. This paper reports the colorimetric properties of dyed poly vinyl alcohol (PVA) nanofibres within the range of 2.5 wt.% to 12.5 wt.% dye content. The electrospinning parameters were fixed at the electrospinning distance of 10 cm, constant feed rate of 0.5 mL/h and applied voltage of 15 kV. The resulting impregnated dye of 10 wt.% exhibits acceptable colour difference of dyed PVA nanofibres, with a mean fibre diameter of 177.1 ± 11.5 nm. The SEM micrographs show the effect of dye content on morphology and fibre diameter upon the increment of dye used. Further increase of dye content adversely affects the jet stability during the electrospinning, resulting in macroscopic dropping phenomenon. The presence of all prominent peaks of Remazol dye in the PVA nanofibers was supported with FTIR analysis. The addition of dye into the nanofibres has resulted in the enhancement of thermal stability of the PVA as demonstrated by TGA analysis.
The present work focuses on the development of cellulose nanofibrils (CNF) film that derived from sustainable biomass resources, which potentially to work as bio-based conductive membranes that assembled into supercapacitors. The chemically purified cellulose was isolated from different parts of coconut (coconut shell and its husk) and further subjected to 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation for CNF preparation. Physicochemical properties of prepared CNFs were studied in terms of chemical characteristics & crystallinity, surface functionalities, surface morphology, and thermal properties. Both coconut shell-derived CNF and coconut husk-derived CNF fulfilled with nanocellulose's characteristics with fibres width ranged of 70-120 nm and 150-330 nm, respectively. CNF films were further prepared by solvent casting method to measure the modulus elasticity, piezoelectric and dielectric properties of the films. Mechanical study indicated that coconut shell-derived CNF film showed a higher value of elastic modulus than the coconut husk-derived CNF film, which was 8.39 GPa and 5.36 GPa, respectively. The effectiveness of electrical aspects for CNF films are well correlated with the crystallinity and thermal properties, associated with it's composition of different coconut's part.
Control synthesis of high quality large-area graphene on transition metals (TMs) by chemical vapor deposition (CVD) is the most fascinating approach for practical device applications. Interaction of carbon atoms and TMs is quite critical to obtain graphene with precise layer number, crystal size and structure. Here, we reveal a solid phase reaction process to achieve Cu assisted graphene growth in nanoscale by in-situ transmission electron microscope (TEM). Significant structural transformation of amorphous carbon nanofiber (CNF) coated with Cu is observed with an applied potential in a two probe system. The coated Cu particle recrystallize and agglomerate toward the cathode with applied potential due to joule heating and large thermal gradient. Consequently, the amorphous carbon start crystallizing and forming sp(2) hybridized carbon to form graphene sheet from the tip of Cu surface. We observed structural deformation and breaking of the graphene nanoribbon with a higher applied potential, attributing to saturated current flow and induced Joule heating. The observed graphene formation in nanoscale by the in-situ TEM process can be significant to understand carbon atoms and Cu interaction.
A double SAW resonator system was developed as a novel method for gas sensing applications. The proposed system was investigated for hydrogen sensing. Commercial Surface Acoustic Wave (SAW) resonators with resonance frequencies of 433.92 MHz and 433.42 MHz were employed in the double SAW resonator system configuration. The advantages of using this configuration include its ability for remote measurements, and insensitivity to vibrations and other external disturbances. The sensitive layer is composed of functionalized multiwalled carbon nanotubes and polyaniline nanofibers which were deposited on pre-patterned platinum metal electrodes fabricated on a piezoelectric substrate. This was mounted into the DSAWR circuit and connected in parallel. The sensor response was measured as the difference between the resonance frequencies of the SAW resonators, which is a measure of the gas concentration. The sensor showed good response towards hydrogen with a minimum detection limit of 1%.
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.
Point-of-care biosensors are important tools developed to aid medical diagnosis and testing, food safety and environmental monitoring. Paper-based biosensors, especially nucleic acid-based lateral flow assays (LFA), are affordable, simple to produce and easy to use in remote settings. However, the sensitivity of such assays to infectious diseases has always been a restrictive challenge. Here, we have successfully electrospun polycaprolactone (PCL) on nitrocellulose (NC) membrane to form a hydrophobic coating to reduce the flow rate and increase the interaction rate between the targets and gold nanoparticles-detecting probes conjugates, resulting in the binding of more complexes to the capture probes. With this approach, the sensitivity of the PCL electrospin-coated test strip has been increased by approximately ten-fold as compared to the unmodified test strip. As a proof of concept, this approach holds great potential for sensitive detection of targets at point-of-care testing.
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.
Fabrication of composite scaffolds is one of the strategies proposed to enhance the functionality of tissue-engineered scaffolds for improved tissue regeneration. By combining multiple elements together, unique biomimetic scaffolds with desirable physical and mechanical properties can be tailored for tissue-specific applications. Despite having a highly porous structure, the utility of electrospun fibers (EF) as scaffold is usually hampered by their insufficient mechanical strength. In this study, we attempted to produce a mechanically competent scaffold with cell-guiding ability by fabricating aligned poly lactic-co-glycolic acid (PLGA) fibers on decellularized human amniotic membrane (HAM), known to possess favorable tensile and wound healing properties. Decellularization of HAM in 18.75 μg/mL of thermolysin followed by a brief treatment in 0.25 M sodium hydroxide efficiently removed the amniotic epithelium and preserved the ultrastructure of the underlying extracellular matrix. The electrospinning of 20% (w/v) PLGA 50:50 polymer on HAM yielded beadless fibers with straight morphology. Subsequent physical characterization revealed that EF-HAM scaffold with a 3-min fabrication had the most aligned fibers with the lowest fiber diameter in comparison with EF-HAM 5- and 7-min scaffolds. Hydrated EF-HAM scaffolds with 3-min deposition had a greater tensile strength than the other scaffolds despite having thinner fibers. Nevertheless, wet HAM and EF-HAMs regardless of the fiber thicknesses had a significantly lower Young's modulus, and hence, a higher elasticity compared with dry HAM and EF-HAMs. Biocompatibility analysis showed that the viability and migration rate of skeletal muscle cells on EF-HAMs were similar to control and HAM alone. Skeletal muscle cells seeded on HAM were shown to display random orientation, whereas cells on EF-HAM scaffolds were oriented along the alignment of the electrospun PLGA fibers. In summary, besides having good mechanical strength and elasticity, EF-HAM scaffold design decorated with aligned fiber topography holds a promising potential for use in the development of aligned tissue constructs.
Far-flung evolution in tissue engineering enabled the development of bioactive and biodegradable materials to generate biocomposite nanofibrous scaffolds for bone repair and replacement therapies. Polymeric bioactive nanofibers are to biomimic the native extracellular matrix (ECM), delivering tremendous regenerative potentials for drug delivery and tissue engineering applications. It's been known from few decades that Zinc oxide (ZnO) nanoparticles are enhancing bone growth and providing proliferation of osteoblasts when incorporated with hydroxyapatite (HAp). We attempted to investigate the interaction between the human foetal osteoblasts (hFOB) with ZnO doped HAp incorporated biocomposite poly(L-lactic acid)-co-poly(ε-caprolactone) and silk fibroin (PLACL/SF) nanofibrous scaffolds for osteoblasts mineralization in bone tissue regeneration. The present study, we doped ZnO with HAp (ZnO(HAp) using the sol-gel ethanol condensation technique. The properties of PLACL/SF/ZnO(HAp) biocomposite nanofibrous scaffolds enhanced with doped and blended ZnO/HAp were characterized using Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Contact angle and Tensile studies to determine the morphology, functionality, wettability and stability. The in vitro study results showed that the addition of ZnO and HAp enhances the secretion of bone mineral matrix (98%) with smaller fiber diameter (139.4 ± 27 nm) due to the presence of silk fibroin showing potential tensile properties (322.4%), and increased the proliferation of osteoblasts for bone tissue regeneration.
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.
Electrospinning is a common method to prepare nanofiber scaffolds for tissue engineering. One of the common cellulose esters, cellulose acetate butyrate (CAB), has been electrospun into nanofibers and studied. However, the intrinsic hydrophobicity of CAB limits its application in tissue engineering as it retards cell adhesion. In this study, the properties of CAB nanofibers were improved by fabricating the composite nanofibers made of CAB and hydrophilic polyethylene glycol (PEG). Different ratios of CAB to PEG were tested and only the ratio of 2:1 resulted in smooth and bead-free nanofibers. The tensile test results show that CAB/PEG composite nanofibers have 2-fold higher tensile strength than pure CAB nanofibers. The hydrophobicity of the composite nanofibers was also reduced based on the water contact angle analysis. As the hydrophilicity increases, the swelling ability of the composite nanofiber increases by 2-fold with more rapid biodegradation. The biocompatibility of the nanofibers was tested with normal human dermal fibroblasts (NHDF). The cell viability assay results revealed that the nanofibers are non-toxic. In addition to that, CAB/PEG nanofibers have better cell attachment compared to pure CAB nanofibers. Based on this study, CAB/PEG composite nanofibers could potentially be used as a nanofiber scaffold for applications in tissue engineering.
A weak ion-exchange membrane (P-COOH) was synthesized by alkaline hydrolysis of a polyacrylonitrile nanofiber membrane prepared by electrospinning process. The P-COOH membrane was characterized for its physical properties and its application for purification of lysozyme from chicken egg white was investigated. The lysozyme adsorption efficiency of the P-COOH membrane operating in a stirred cell contactor (Millipore, Model 8010) was evaluated. The effects of key parameters such as the feed concentration, the rotating speed, the flow rate of feed and the operating pressure were studied. The results showed successful purification of lysozyme with a high recovery yield of 98% and a purification factor of 63 in a single step. The purification strategy was scaled-up to the higher feedstock loading volume of 32.7 and 70 mL using stirred cell contactors of Model 8050 and 8200, respectively. The scale-up processes achieved similar purification results, proving linear scalability of the purification technique adopted.
Enzyme immobilization has been known to be one of the methods to improve the stability and reusability of enzyme. In this study, a strategy to optimize laccase immobilization on polyethylene terephthalate grafted with maleic anhydride electrospun nanofiber mat (PET-g-MAH ENM) was developed. The development involves the screening and optimization processes of the crucial factors that influence the immobilization yield such as enzyme concentration, pH values, covalent bonding (CV) time, CV temperature, crosslinking (CL) time, CL temperature and glutaraldehyde concentration using two-level factorial design and Box-Behnken design (BBD), respectively. It was found that laccase concentration, pH values and glutaraldehyde concentration play important role in enhancing the immobilization yield of laccase on PET-g-MAH ENM in the screening process. Subsequently, the optimization result showed at 0.28 mg/ml laccase concentration, pH 3 and 0.45% (v/v) glutaraldehyde concentrations gave the highest immobilization yield at 87.64% which was 81.2% increment from the immobilization yield before optimization. Under the optimum condition, the immobilized laccase was able to oxidize 2, 2-azino-bis 3-ethylbenzothiazoline-6- sulfonic acid (ABTS) in a broad range of pH (pH 3-6) and temperature (20- 70 °C). Meanwhile, the kinetic parameters for Km and Vmax were 1.331 mM and 0.041 mM/min, respectively. It was concluded that the optimization of immobilized laccase on PET-g-MAH ENM enhance the performance of this biocatalyst.
Electrospinning technology was applied for the preparation of polyacrylonitrile (PAN) nanofiber membrane in this work. After hot pressing, alkaline hydrolysis and neutralization treatment, a weak acid cation exchange membrane (P-COOH) was prepared. By the covalent coupling reaction between the acidic membrane and aminomethane sulfonic acid (AMSA), a strong acidic nanofiber membrane (P-SO3H) was obtained. The surface morphology, chemical structure, and thermal stability of the prepared ion exchange membranes were analyzed via SEM, FTIR and TGA. Analytical results showed that the membranes were prepared successfully and thermally stable. The ion exchange membrane (IEX) was conducted with the newly designed membrane reactor, and different operating conditions affecting the adsorption efficiency of Toluidine Blue dye (TBO) were investigated by dynamic flow process. The results showed that dynamic binding capacity (DBC) of weak and strong IEX membranes for TBO dye was ~170 mg/g in a dynamic flow process. Simultaneously, the ion exchange membranes were also used for purifying lysozyme from chicken egg white (CEW). Results illustrated that the recovery yield and purification factor of lysozyme were 93.43% and 29.23 times (P-COOH); 90.72% and 36.22 times (P-SO3H), respectively. It was revealed that two type ion exchange membranes were very suitable as an adsorber for use in dye waste treatment and lysozyme purification process. P-SO3H strong ion-exchange membrane was more effective either removal of TBO dye or purification of lysozyme. The ion exchange membranes not only effectively purified lysozyme from CEW solution, but also effectively removed dye from wastewater.
Polyacrylonitrile nanofiber membrane functionalized with tris(hydroxymethyl)aminomethane (P-Tris) was used in affinity membrane chromatography for lysozyme adsorption. The effects of pH and protein concentration on lysozyme adsorption were investigated. Based on Langmuir model, the adsorption capacity of P-Tris nanofiber membrane was estimated to be 345.83 mg/g. For the operation of dynamic membrane chromatography with three-layer P-Tris nanofiber membranes, the optimal operating conditions were at pH 9, 1.0 mL/min of feed flow rate, and 2 mg/mL of feed concentration. Chicken egg white (CEW) was applied as the crude feedstock of lysozyme in the optimized dynamic membrane chromatography. The percent recovery and purification factor of lysozyme obtained from the chromatography were 93.28% and 103.98 folds, respectively. Our findings demonstrated the effectiveness of P-Tris affinity nanofiber membrane for the recovery of lysozyme from complex CEW solution.
Cellulose acetate (CA) is a remarkable biomaterial most extensively used in biomedical applications due to their properties. This review highlighted the synthesis and chemical structure of CA polymer as well as focused on the mechanical, chemical, thermal, biocompatible, and biodegradable properties of electrospun CA nanofibers. These properties are essential in the evaluation of the CA nanofibers and provide information as a reference for the further utilization and improvement of CA nanofibers. Moreover, we have summarized the use of electrospun CA nanofibers in the drug delivery system as a carrier for drugs and classify them according to the drug class, including anti-inflammatory, anticancer, antioxidant, antimicrobial agents, vitamins and amino acids. Our review has been concluded that CA nanofibers cannot wholly be biodegraded within the human body due to the absence of cellulase enzyme but degraded by microorganisms. Hence, the biodegradation of CA nanofibers in vivo has addressed as a critical challenge.
Adsorption of lysozyme on the dye-affinity nanofiber membranes was investigated in batch and dynamic modes. The membrane matrix was made of electrospun polyacrylonitrile nanofibers that were grafted with ethylene diamine (EDA) and/or chitosan (CS) for the coupling of Reactive Blue 49 dye. The physicochemical properties of these dye-immobilized nanofiber membranes (P-EDA-Dye and P-CS-Dye) were characterized microscopically, spectroscopically and thermogravimetrically. The capacities of lysozyme adsorption by the dye-affinity nanofiber membranes were evaluated under various conditions, namely pH, dye immobilized density, and loading flow rate. The adsorption of lysozyme to the dye-affinity nanofiber membranes was well fitted by Langmuir isotherm and pseudo-second kinetic models. P-CS-Dye nanofiber membrane had a better performance in the dynamic adsorption of lysozyme from complex chicken egg white solution. It was observed that after five cycles of adsorption-desorption, the dye-affinity nanofiber membrane did not show a significant loss in its capacity for lysozyme adsorption. The robustness as well as high dynamic adsorption capability of P-CS-Dye nanofiber membrane are promising for the efficient recovery of lysozyme from complex feedstock via nanofiber membrane chromatography.
In this study, laccase was immobilized on nylon 6,6/Fe(3+) composite (NFC) nanofibrous membrane and used for the detoxification of 3,3'-dimethoxybenzidine (DMOB). The average size and tensile strength of the NFC membrane were found to be 60-80 nm (diameter) and 2.70 MPa, respectively. The FTIR results confirm that the amine (N-H) group of laccase was attached with Fe(3+) particles and the carbonyl (C=O) group of NFC membrane via hydrogen bonding. The half-life of the laccase-NFC membrane storage stability was increased from 6 to 11 weeks and the reusability was significantly extended up to 43 cycles against ABTS oxidation. Enhanced electro-oxidation of DMOB by laccase was observed at 0.33 V and the catalytic current was found to be 30 µA. The DMOB-treated mouse fibroblast 3T3-L1 preadipocytes showed maximum (97 %) cell inhibition at 75 µM L(-1) within 24 h. The cytotoxicity of DMOB was significantly decreased to 78 % after laccase treatment. This study suggests that laccase-NFC membrane might be a good candidate for emerging pollutant detoxification.