Use Of Nanofibers Research Articles

Characterization of carbon based nanofibers in nanocomposites and their applications

Now-a-days nanocomposites are used in almost all fields due to enhanced properties. Nanocomposite is composed of nanofibers and matrix. Due to large area to volume ratio nanofibers play a vital role in determining the characteristics of the nanocomposites. In this study it has been discussed about various properties of the carbon nanofibers in various matrix. From the study it is observed that mechanical properties like hardness, tensile strength are greatly affected by the size of nanofibers. By increasing CNF percentage in epoxy matrix it is observed that mechanical strength increased by 49%. Similarly other propertieslike physical property, electrical property, thermal property etc. get improved by the use of nanofibers. Materials having higher thermal conductivity such as Carbon and Diamond are introduced in the composite so as to increase thermal conductivity of nanocomposite. Generally the carbon based nanocomposites are used as supercapacitor, air purifier, battery and sensor.

Mechanism and characteristics of Au-functionalized SnO2/In2O3 nanofibers for highly sensitive CO detection

In this study, SnO2 doped In2O3 nanofibers were prepared using an electrospinning method and subjected to a series of analyses using TGA, XRD, SEM, TEM, and XPS. The gold nanoparticles were then sputtered onto nanofibers for use in a carbon monoxide (CO) gas sensor. The gas sensing results show that 4 wt% SnO2 doped In2O3 nanofibers with gold coating for 20 s (gold particle size of about 14 ± 3 nm) have the best CO sensing response. The best CO gas response is 29.2%, with good recovery and reproducibility.

Evolution of aerial spider webs coincided with repeated structural optimization of silk anchorages

Physical structures built by animals challenge our understanding of biological processes and inspire the development of smart materials and green architecture. It is thus indispensable to understand the drivers, constraints, and dynamics that lead to the emergence and modification of building behavior. Here, we demonstrate that spider web diversification repeatedly followed strikingly similar evolutionary trajectories, guided by physical constraints. We found that the evolution of suspended webs that intercept flying prey coincided with small changes in silk anchoring behavior with considerable effects on the robustness of web attachment. The use of nanofiber based capture threads (cribellate silk) conflicts with the behavioral enhancement of web attachment, and the repeated loss of this trait was frequently followed by physical improvements of web anchor structure. These findings suggest that the evolution of building behavior may be constrained by major physical traits limiting its role in rapid adaptation to a changing environment.

Hierarchical assembly of manganese dioxide nanosheets on one-dimensional titanium nitride nanofibers for high-performance supercapacitors

MnO2 has attracted considerable attention for use in supercapacitors. Nevertheless, its low electrical conductivity greatly hinders its potential application. Here, we demonstrate the fabrication of a high-performance electrode material via facile coating of hierarchical MnO2 nanosheets onto highly electrically conductive one-dimensional (1D) TiN nanofibers for use in supercapacitors. The TiN nanofibers are prepared through nitridation electrospinning of TiO2 nanofibers via ammonia annealing. The obtained TiN@MnO2 composites exhibit enhanced electrochemical properties, such as high specific capacitance of 386 F/g at a current density of 1 A/g, and long cycle stability of ∼111.7% capacity retention after 4000 cycles at 6 A/g. The unique nanostructure and significant synergistic effect between TiN and MnO2 are responsible for its good electrochemical performance.

The Use of Nanofibers in the Clothing Industry

The Use of Nanofibers in the Clothing Industry

Electrospinning Nanofibers for Therapeutics Delivery.

The limitations of conventional therapeutic drugs necessitate the importance of developing novel therapeutics to treat diverse diseases. Conventional drugs have poor blood circulation time and are not stable or compatible with the biological system. Nanomaterials, with their exceptional structural properties, have gained significance as promising materials for the development of novel therapeutics. Nanofibers with unique physiochemical and biological properties have gained significant attention in the field of health care and biomedical research. The choice of a wide variety of materials for nanofiber fabrication, along with the release of therapeutic payload in sustained and controlled release patterns, make nanofibers an ideal material for drug delivery research. Electrospinning is the conventional method for fabricating nanofibers with different morphologies and is often used for the mass production of nanofibers. This review highlights the recent advancements in the use of nanofibers for the delivery of therapeutic drugs, nucleic acids and growth factors. A detailed mechanism for fabricating different types of nanofiber produced from electrospinning, and factors influencing nanofiber generation, are discussed. The insights from this review can provide a thorough understanding of the precise selection of materials used for fabricating nanofibers for specific therapeutic applications and also the importance of nanofibers for drug delivery applications.

Preparation and Characterization of Electrospun Gelatin Nanofibers for Use as Nonaqueous Electrolyte in Electric Double-Layer Capacitor

A novel nanofibrous gel electrolyte was prepared via gelatin electrospinning for use as a nonaqueous electrolyte in electric double-layer capacitors (EDLCs). An electrospinning technique with a 25 wt% gelatin solution was applied to produce gelatin electrospun (GES) nanofiber electrolytes. Structural analysis of the GES products showed a clearly nanofibrous structure with fiber diameters in the 306.2–428.4 nm range and exhibiting high thermal stability, high tensile strength, and a stable form of nanofibrous structure after immersion in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4). After testing over a range of spinning times, GES electrolytes that were produced at 25 min (GES-25) had a suitable thickness for the assembly of EDLC with the optimized tensile properties and were used to fabricate EDLC test cells with EMImBF4. These test cells were compared to those with pure EMImBF4 and a separator as an electrolyte. The electrochemical properties of the test cells were characterized by charge-discharge testing, discharge capacitance, and alternative current (AC) impedance measurements. AC impedance measurements showed that the test cell with the GES-25/EMImBF4 gel electrolyte showed slightly poorer contact with the electrode when compared to that with pure EMImBF4, whereas exhibited comparable IR drop and discharge capacitance (calculated capacitance retention was 56.6%). The results demonstrated that this novel gel electrolyte can be used as a nonaqueous electrolyte in order to improve the safety in EDLCs.

Sonication-assisted surface modification method to expedite the water removal from cellulose nanofibers for use in nanopapers and paper making

This paper addresses the issue of high water retention by cellulose nanofibers (CNFs) that lead to exorbitant time consumption in the dewatering of CNF suspensions. This has been a bottleneck, which is restricting the commercialization of CNF derived products such as nanopapers and CNF reinforced paper sheets. As a remedy, we suggest an eco-friendly water-based approach that involves the use of sonication energy and lactic acid (LA) to modify the surface of CNFs. The suggested modification resulted in rapid water drainage, and dewatering was completed in 10 min; with unmodified CNFs, it took around 45 min. We have also compared the draining characteristics of LA modification of CNF suspensions with a common draining agent (NaCl); LA modification drains water 56% faster than the use of NaCl, and produced mechanically superior dimensionally stable nanopaper. Additionally, LA modification allows the addition of 10 wt.% CNF in paper sheets, with dewatering done in 2 min (while the unmodified CNFs took 23 min).

ZnO Nanofiber Thin‐Film Transistors with Low‐Operating Voltages

AbstractAlthough significant progress has been made towards using ZnO nanofibers (NFs) in future high‐performance and low‐cost electronics, they still suffer from insufficient device performance caused by substantial surface roughness (i.e., irregularity) and granular structure of the obtained NFs. Here, a simple one‐step electrospinning process (i.e., without hot‐press) is presented to obtain controllable ZnO NF networks to achieve high‐performance, large‐scale, and low‐operating‐power thin‐film transistors. By precisely manipulating annealing temperature during NF fabrication, their crystallinity, grain size distribution, surface morphology, and corresponding device performance can be regulated reliably for enhanced transistor performances. For the optimal annealing temperature of 500 °C, the device exhibits impressive electrical characteristics, including a small positive threshold voltage (Vth) of ≈0.9 V, a low leakage current of ≈10−12 A, and a superior on/off current ratio of ≈106, corresponding to one of the best‐performed ZnO NF devices reported to date. When high‐κ AlOx thin films are employed as gate dielectrics, the source/drain voltage (VDS) can be substantially reduced by 10× to a range of only 0–3 V, along with a 10× improvement in mobility to a respectable value of 0.2 cm2 V−1 s−1. These results indicate the potential of these nanofibers for use in next‐generation low‐power devices.

Investigating the performance of drug delivery system of fluconazole made of nano-micro fibers coated on cotton/polyester fabric.

Polymer-based drug delivery systems are suitable to optimize the therapeutic properties of drugs and to render them safer, more effective and reliable. Long-term or repeated use of oral administration of fluconazole for treating chronic candidiasis in the patient and partially abandoned treatment lead to the resistant strains of the fungus Candida albicans and severity of the disease. In this study, the use of nanofibers and microfibers containing fluconazole for local drug delivery to increase the efficiencies and reduce the side effects caused by taking the drug was studied. Morphology, microstructure and chemical composition of PVA nanofibers containing fluconazole were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). As well as, the DSC test was indicated presence of fluconazole in PVA fibrous mats. The rate of drug release was investigated by UV-Vis spectrophotometery and swelling technique. SEM images showed that the nanofibers with uniform structure without beads were produced. The mechanical properties of the pristine PVA nanofiber and fibrous mat containing drug were evaluated. The release of fluconazole from PVA nanofibers in pH of 7.4 and at 37 °C was investigated. The results presented that the drug release rate is dependent on the morphology and structure of PVA nanofibers and could be adjusted in desired dosage. The presented products are applicable in the high production form for medical textile industry.

(Invited) Intelligent Innovation in the Water Sector. Opportunities and Challenges in Sensor Design for the Drinking and Wastewater Markets

The water and wastewater industries face many challenges in providing safe drinking water, sanitary services and environmental protection to the public. The dynamic nature of our water systems along with new regulations, emerging contaminants and increasing environmental concerns combined with the constant pressure to reduce operating costs and conserve energy make the development of sensors for the water industry a field ripe with opportunity. As with all areas of opportunity, to be successful in developing sensors for the water industry there are hurdles to overcome and pitfalls to be avoided. Harsh environmental conditions in wastewater sensor deployment scenarios are a given, but, the severe conditions commonly encountered in drinking water applications are often not addressed with the diligence that they merit. Factors such as debris in the pipes, turbidity, fluctuating pH, various types and levels of disinfectants and other water treatment chemicals; fluctuating redox conditions and variable conductivity are just a few of the complicating elements that can hamper sensor development. Once a sensor has been developed the last hurdle has been by no means cleared. The water industry is a notoriously reactionary group. The barriers to change are extremely large and adoption curves for new technologies tend to be extremely slow. One of the chief factors in these slow adoption rates is the glacial pace of regulatory acceptance of new methods. Even for measurements not taken for reporting purposes, the industry tends to favor methods that have EPA or other regulatory body approval. Unfortunately, this approval process can take several years (2 to 3 years for drinking water and up to 7 years for wastewater applications). There are several industry initiatives sponsored by groups, such as the Water Environment Federation, that are attempting to speed up the innovation curve in the water industry but these groups are just beginning to act and it is unknown if they will meet with success. In this presentation, the above constraints will be discussed, as well as others, which are commonly encountered in the research and development cycle for sensors tailored to the water industry. Examples of obstacles encountered in a recent development project initiated for the use of nano-fibers in sensors for the water industry will be utilized to illustrate various points. A thorough knowledge of the technological pitfalls to be avoided as well as an understanding of the market and regulatory forces that can come into play in this market arena will lead to the development of robust sensors that serve the industry and help to ensure developers of a reasonable return on investment.

Nanofiber Scaffolds as Drug Delivery Systems to Bridge Spinal Cord Injury.

The complex pathophysiology of spinal cord injury (SCI) may explain the current lack of an effective therapeutic approach for the regeneration of damaged neuronal cells and the recovery of motor functions. A primary mechanical injury in the spinal cord triggers a cascade of secondary events, which are involved in SCI instauration and progression. The aim of the present review is to provide an overview of the therapeutic neuro-protective and neuro-regenerative approaches, which involve the use of nanofibers as local drug delivery systems. Drugs released by nanofibers aim at preventing the cascade of secondary damage (neuro-protection), whereas nanofibrous structures are intended to re-establish neuronal connectivity through axonal sprouting (neuro-regeneration) promotion, in order to achieve a rapid functional recovery of spinal cord.

Mesenchymal stem cells cultivated on scaffolds formed by 3D printed PCL matrices, coated with PLGA electrospun nanofibers for use in tissue engineering

Materials, such as biopolymers, can be applied to produce scaffolds as mechanical support for cell growth in regenerative medicine. Two examples are polycaprolactone (PCL) and poly (lactic-co-glycolic acid) (PLGA), both used in this study to evaluate the behavior of umbilical cord-derived mesenchymal stem cells. The scaffolds were produced by the 3D printing technique using PCL as a polymer covered with PLGA fibers obtained by electrospinning. The cells were seeded in three concentrations: 8.5 × 103; 25.5 × 103 and 51.0 × 103 on the two surfaces of the scaffolds. With scanning electron microscopy (SEM), it was observed that the electrospun fibers were integrated into the 3D printed matrices. Confocal laser scanning microscopy and SEM confirmed the presence of attached cells and the lactate dehydrogenase release test showed the scaffolds were not cytotoxic. The cells were able to differentiate into osteogenic and chondrogenic lineages on the scaffolds. Mechanical test showed that the cells seeded on the 3D printed PCL matrices coated with PLGA electrospun nanofibers (3D + ES + SC) did not show significant difference in tensile modulus than the pure PCL matrix (3D) or PCL matrices coated with PLGA electrospun nanofibers (3D + ES). The combination of the two polymers facilitated the production of a support with greater mechanical stability due to the presence of the 3D printed PCL matrices fabricated by melted filaments and greater cell adhesion due to the PLGA fibers. The scaffolds are suitable for use in cell therapy and also for tissue regeneration purposes.

Nanofibers: New Insights for Drug Delivery and Tissue Engineering.

Nanofibers became one of the major research areas for drug delivery and tissue engineering applications in the last decade. Depending on the simplicity of the preparation method and high drug loading capacity, nanofibers provide many advantages for therapeutic perspectives. In addition, combined systems such as embedding nanoparticles into the nanofiber structures provide a second option for delivery of dual active ingredients in the same formulation. The release rate of the active ingredients can also be modified easily by the formulation parameters depending on the desired release time for treatment. Nanofibers systems are used for the delivery of antibiotics, anticancer drugs, analgesics, hemostatic agents and various proteins for tissue engineering purposes. In addition, various applications such as medical device coating also provide new insights for the clinical use of nanofibers. The most commonly used technique for preparation of nanofibers is the electrospinning, which provides feasibility background for scale up process from laboratory to the industrial applications. The main boundary for nanofibers is the limitations for systemic route. Nanofibers are mainly designed for the delivery of active ingredients for local purposes. Regardless of the therapeutic aim, nanofibers are also perfect 3 dimensional structures that are suitable for tissue regeneration. They provide matrix structure for cell regeneration especially in applications for wound healing. This review is mainly focused on the recent advances on the preparation of nanofibers, applications for drug delivery, tissue engineering and wound healing purposes.

Electrospinning of thermoplastic carboxymethyl cellulose/poly(ethylene oxide) nanofibers for use in drug-release systems

Polymeric delivery systems using electrospun nanofibers have been developed for many applications, notably for drug delivery and tissue engineering in the healthcare industry. In this study, a nanofiber drug carrier was fabricated via two different electrospinning processes, blend and coaxial, using a new degradable thermoplastic carboxymethyl cellulose (TCMC) and poly(ethylene oxide) (PEO). The TCMC was synthesized by graft copolymerization with methyl acrylate. Tetracycline hydrochloride served as a drug model incorporated within these nanofibers and their performance as a drug-carrier scaffold was evaluated. The structure morphology of the obtained nanofibers was viewed under scanning electron microscope, and the changes of the structural of polymer before and after graft and confirmation of incorporation of the drug on the fibers was characterized by Fourier transform infrared spectroscopy. Response surface methodology was applied to predict the optimum condition for fabrication of the nanofibers. The drug-delivery profile showed that drug release from the optimized core–shell sample TCMC 3% (w/v)/PEO 1% (w/v) was much slower than for the blend nanofibers and was sustained for 72h with only 26.06% burst release within the first 30min. The drug-loaded TCMC 3% (w/v)/PEO 1% (w/v) core–shell sample nanofibers showed excellent bactericidal activity against a wide range of bacteria, indicating their potential as antibacterial materials in various applications such as tissue engineering and pharmaceutical science.

Preparation and molten salt-assisted KOH activation of porous carbon nanofibers for use as supercapacitor electrodes

Carbon nanofiber paper was prepared by electrospinning from thermosetting phenolic resin, followed by activation via KOH-containing molten salt at high temperature. By adding a small dosage of KOH in the molten salt the porous volume and specific surface area could be greatly improved. The obtained porous carbon nanofibers had a specific surface area of 1007 m2 g−1, total pore volume of 0.363 cm3 g−1, micropore volume of 0.247 cm3 g−1. The electrochemical measurements in 6 M KOH aqueous solution showed that the porous carbon nanofibers possessed high specific capacitance and considerable rate performance. The maximal specific capacitance of 288 F g−1 was achieved at 0.2 A g−1 and the specific capacitance could still remain 204 F g− 1 at 20 A g−1 with the retention of 71%. In the molten salt system, the reaction between activating agent and carbon could be more efficient, hence, such molten salt-assisted activation method was considered as a general activation method for the high-specific-surface-areaed carbons.

Enhancing water swelling ability and mechanical properties of water‐swellable rubber by PAA/SBS nanofiber mats

ABSTRACTInvestigation of the potential use of nanofibers to reinforce composites has gained significance in many applications. In this article, the nanofiber mats of poly(acrylic acid) (PAA) and styrene–butadiene–styrene (SBS) triblock copolymer with composites structure were interweaved by double needle electrospinning process. The multiple nanofiber mats were added to conventional water‐swellable rubber (WSR). Improved mechanical and physical properties of WSR were obtained. Enhancement of the swellability of WSR + PAA/SBS nanofiber mats was derived from the PAA constituent absorbing water from the surface into the bulk and introducing random internal water channels between discontinuous superabsorbent polymers. The role of SBS nanofibers in the composite of WSR + PAA/SBS nanofiber mats was more related to the mechanical properties, where the breaking force of the composite increased to twice that of the conventional WSR. Interestingly, after immersion of the WSR + PAA/SBS nanofiber mats in water for 1 week, there was only a slight decrease in their mechanical properties of less than 5% compared to the dry state. The mechanisms and effects of the nanofiber mats in enhancing the mechanical and water swelling properties of WSR are also discussed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44213.

Recent Applications of Coaxial and Emulsion Electrospinning Methods in the Field of Tissue Engineering.

Electrospinning has emerged as an effective method of producing nanoscale fibers for use in multiple fields of study. One area of significant interest is nanofiber utilization for tissue engineering because the nanofibrous mats can mimic the native extracellular matrix of biological tissues. A logical next step is the inclusion of certain molecules and compounds to accelerate or increase the efficacy of tissue regeneration. Two methods are under scrutiny for their capability to encapsulate therapeutic compounds within electrospun nanofibers: emulsion and coaxial electrospinning. Both have advantages and disadvantages, which need to be taken into careful consideration when deciding to use them in a specific application. Several examples are provided here to highlight the vast potential of multilayered nanofibers as well as the emergence of new techniques to produce three-dimensional scaffolds of nanofibers for use in the field of tissue engineering.

Biosensor based on electrospun blended chitosan-poly (vinyl alcohol) nanofibrous enzymatically sensitized membranes for pirimiphos-methyl detection in olive oil

An ultra-sensitive electrochemical biosensor was successfully developed for rapid detection of pirimiphos-methyl in olive oil, based of genetically-engineered acetylcholinesterase (AChE) immobilization into electrospun chitosan/poly (vinyl alcohol) blend nanofibers. Due to their unique properties such as spatial structure, high porosity, and large surface area, the use of nanofibers allowed improving the biosensor response by two folds. The developed biosensor showed a good performance for detecting pirimiphos-methyl, with a limit of detection of 0.2nM, a concentration much lower than the maximum residue limit allowed set by international regulations (164nM). The biosensor was used for the detection of pirimiphos-methyl in olive oil samples after a simple liquid-liquid extraction, and the recovery rates were close to 100%.

Photosensitizer-Embedded Polyacrylonitrile Nanofibers as Antimicrobial Non-Woven Textile.

Toward the objective of developing platform technologies for anti-infective materials based upon photodynamic inactivation, we employed electrospinning to prepare a non-woven textile comprised of polyacrylonitrile nanofibers embedded with a porphyrin-based cationic photosensitizer; termed PAN-Por(+). Photosensitizer loading was determined to be 34.8 nmol/mg material; with thermostability to 300 °C. Antibacterial efficacy was evaluated against four bacteria belonging to the ESKAPE family of pathogens (Staphylococcus aureus; vancomycin-resistant Enterococcus faecium; Acinetobacter baumannii; and Klebsiella pneumonia), as well as Escherichia coli. Our results demonstrated broad photodynamic inactivation of all bacterial strains studied upon illumination (30 min; 65 ± 5 mW/cm2; 400–700 nm) by a minimum of 99.9996+% (5.8 log units) regardless of taxonomic classification. PAN-Por(+) also inactivated human adenovirus-5 (~99.8% reduction in PFU/mL) and vesicular stomatitis virus (>7 log units reduction in PFU/mL). When compared to cellulose-based materials employing this same photosensitizer; the higher levels of photodynamic inactivation achieved here with PAN-Por(+) are likely due to the combined effects of higher photosensitizer loading and a greater surface area imparted by the use of nanofibers. These results demonstrate the potential of photosensitizer-embedded polyacrylonitrile nanofibers to serve as scalable scaffolds for anti-infective or self-sterilizing materials against both bacteria and viruses when employing a photodynamic inactivation mode of action.