Nanofibers

Introduction-Eliminating and/or inhibiting bacterial growth within the root canal system have been shown to play a key role in the regenerative outcome. The aim of this study was to synthesize and determine in vitro both the antimicrobial effectiveness and cytocompatibility of bi-mix antibiotic-containing polydioxanone (PDS)-based polymer scaffolds. Methods-Antibiotic-containing (metronidazole, MET and ciprofloxacin, CIP) polymer solutions (distinct antibiotic weight ratios) were spun into fibers as a potential mimic to the double antibiotic paste (DAP, a MET/CIP mixture). Fiber morphology, chemical characteristics, and tensile strength were evaluated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and tensile testing, respectively. Antimicrobial efficacy was tested over time (aliquot collection) against Enterococcus faecalis (Ef), Porphyromonas gingivalis (Pg), and Fusobacterium nucleatum (Fn). Similarly, cytotoxicity was evaluated in human dental pulp stem cells (hDPSCs). Data were statistically analyzed (p<0.05). Results-SEM and FTIR confirmed that electrospinning was able to produce antibioticcontaining fibers with diameter mostly in the nanoscale. Tensile strength of 1:1MET/CIP scaffolds was significantly (p<0.05) higher than pure PDS (control). Meanwhile, all other groups presented similar strength as the control. Aliquots obtained from antibiotic-containing scaffolds inhibited growth of Ef, Pg and Fn, except pure MET that did not show an inhibitory action towards Pg or Fn. Antibiotic-containing aliquots promoted slight hDPSCs viability reduction, but none of them were considered to be cytotoxic.

Dimensional reduction of ZnO semiconductors is expected to create wide-ranging application possibilities from roomtemperature ultraviolet (UV) lasers, sensors, photocatalysts, solar cells, [4] to field-emission (FE) devices. In general, ZnO nanowires as one-dimensional (1D) materials with diameters of less than 10 nm are expected to display novel and unique physical and chemical properties due to quantum confinement. Furthermore, it is very important to fabricate a dense array of ZnO nanowires on an appropriate substrate so that the nanowires can be directly addressed, surface area can be optimized, and/or collective properties may be induced. A host of techniques have been developed for the synthesis of aligned 1D ZnO nanostructures with sizes in the range of 10-100 nm on a variety of substrates for nanodevice applications. [6] For example, well-aligned ZnO nanowires that are 10-15 nm across have been grown from patterned, thin gold dots on sapphire substrates by a vapor-liquid-solid (VLS) process. To our knowledge, however, little has been reported on the synthesis of well-aligned ZnO nanowires with diameters of less than 10 nm. Although 6nm ZnO nanobelts have been obtained by solid-vapor deposition, [9] they are randomly oriented. Therefore, one of the synthetic challenges of nanowire materials is to reduce the nanowire diameter and, at the same time, align the nanowires in a controlled fashion. Here, we demonstrate the first synthesis of aligned ZnO nanofibers, which are no thicker than 10 nm and % 500 nm in length, by hydrothermal treatment of a Zn foil in an ammonia/alcohol aqueous solution. It should be emphasized that the reaction was carried out at a relatively low temperature without any catalyst. We have established that the use of ammonia/alcohol is crucial to the growth of the aligned ultrathin ZnO nanofibers. Photoluminescence (PL) measurement at room temperature shows a prominent peak at 373 nm (3.32 eV), which is about 100 meV blue-shifted from the bulk ZnO emission (3.24 eV, 383 nm) due to the ultrafine dimension along the radial direction of the ZnO nanofibers.

Jet-based technologies are increasingly being explored as potential high-throughput and high-resolution methods for the manipulation of biological materials. Previously shown to be of use in generating scaffolds from biocompatible materials, we were interested to explore the possibility of using electrospinning technology for the generation of scaffolds comprised of living cells. For this, it was necessary to identify appropriate parameters under which viable threads containing living cells could be produced. Here, we describe a method of electrospinning that can be used to deposit active biological threads and scaffolds. This has been achieved by use of a coaxial needle arrangement where a concentrated living biosuspension flows through the inner needle and a medicalgrade poly(dimethylsiloxane) (PDMS) medium with high viscosity (12 500 mPa s) and low electrical conductivity (10 -15 S m -1 ) flows through the outer needle. Using this technique, we have identified the operational conditions under which the finest cell-bearing composite microthreads are formed. Collected cells that have been cultured, postelectrospinning, have been viable and show no evidence of having incurred any cellular damage during the bionanofabrication process. This study demonstrates the feasibility of using coaxial electrospinning technology for biological and biomedical applications requiring the deposition of living cells as composite microthreads for forming active biological scaffolds.

In this investigation, the nanofiber formation ability of gellan, a FDA approved low cost natural polysaccharide, has been achieved for the first time using electrospinning technique. The gellan based ultrafine nanofibers were fabricated by using a blend mixture of gellan with another biodegradable polymer polyvinyl alcohol (PVA). The morphology of resulting gellan-PVA nanofibers was analyzed using field emission scanning electron microscopy (FESEM). The mass ratio of 50:50 for gellan:PVA was recorded as an optimum solution ratio to obtain uniform bead free nanofibers with an average diameter of 40 ± 15.8 nm. Data depicted that among different parameters evaluated, viscosity and the mass ratio of gellan:PVA were the key parameters that influence the nanofiber morphology and diameter.

Bioactive implants intended for rapid, robust, and durable bone tissue regeneration are presented. The implants are based on nanofibrous 3D-scaffolds of bioresorbable polye-caprolactone mimicking the fibrillar architecture of bone matrix. Layer-by-layer nanoimmobilization of the growth factor BMP-2 in association with chitosan (CHI) or poly-L-lysine over the nanofibers is described. The osteogenetic potential of the scaffolds coated with layers of CHI and BMP-2 is demonstrated in vitro, and in vivo in mouse calvaria, through enhanced osteopontin gene expression and calcium phosphate biomineralization. The therapeutic strategy described here contributes to the field of regenerative medicine, as it proposes a route toward efficient repair of bone defects at reduced risk and cost level.

A novel high-performance polyamide 6, polyacrylonitrile and polyvinylidene fluoride nanofibers were fabricated using industrial production Nanospider equipment for liquid filtration as microfilters. The application of nanofibers has been hindered by their poor mechanical strength. This work developed a feasible approach to preparing mechanically strong nanofiber webs. The mechanical strength of the nanofibers was enhanced using special lamination technique on a supporting layer. Experimental results show that the mechanical strength of the nanofibers enhanced more than 5 times while high porosity and liquid permeability retain. The separation results indicate that nanofibers have a potential to be used in liquid filters.

The development of solid materials which are able to upconvert optical radiation into photons of higher energy is attractive for many applications such as photocatalytic cells and photovoltaic devices. However, to fully exploit triplet-triplet annihilation photon energy upconversion (TTA-UC), oxygen protection is imperative because molecular oxygen is an ultimate quencher of the photon upconversion process. So far, reported solid TTA-UC materials have focused mainly on elastomeric matrices with low barrier properties because the TTA-UC efficiency generally drops significantly in glassy and semicrystalline matrices. To overcome this limit, for example, combine effective and sustainable annihilation upconversion with exhaustive oxygen protection of dyes, we prepare a sustainable solid-state-like material based on nanocellulose. Inspired by the structural buildup of leaves in Nature, we compartmentalize the dyes in the liquid core of nanocellulose-based capsules which are then further ...

Comparative statistical analysis of the infiuence of processing parameters, for electrospinning (ES) and solution blow spinning (SBS) processes, on nanofibrous poly(L-lactic acid) (PLLA) material morphology and average fiber diameter was conducted in order to identify the key processing parameter for tailoring the product properties. Further, a comparative preliminary biocompatibility evaluation was performed. Based on Design of Experiment (DOE) principles, analysis of standard effects of voltage, air pressure, solution feed rate and concentration, on nanofibers average diameter was performed with the Pareto’s charts and the best fitted surface charts. Nanofibers were analyzed by scanning electron microscopy (SEM). The preliminary biocompatibility comparative tests were performed based on SEM microphotographs of CP5 cells cultured on materials derived from ES and SBS. Polymer solution concentration was identified as the key parameter infiuencing morphology and dimensions of nanofibr...

In this study, erbia (Er2O3)-doped Bi2O3 ceramics were prepared from sol–gel derived nanocrystalline powders. The morphological properties were investigated by scanning electron microscopy. X-ray diffraction (XRD) analysis was carried out in order to characterize the phase and crystal structure of the powder samples. Temperature dependent electrical properties were determined by thermogravimetry/differential thermal analyzer (TG/DTA) and 4-point probe techniques. The stable fluorite face centered cubic δ-type phase was observed at room temperature from the XRD result, which was supported by the DTA and temperature dependent electrical conductivity measurements. Electrical conductivity results indicate that there is a transition approximately at 650 °C, which can be attributed to an order–disorder transition (ODT). The activation energy values obtained from the Arrhenius approach for heating and cooling process were presented. Two regimes, corresponding to high temperature region (HTR) and low temperature region (LTR), were observed. As a result of morphological changes during the ODT, the electrical conductivity modifies and the activation energies are different for studied sample at HTR and LTR.

Background: Polymeric scaffolds have achieved immense importance in the field of nerve tissue engineering. Methods: In the present study, the combination of thermally induced phase separation (TIPS) and electrospinning methods were used to fabricate poly-(lactic acid)/gelatin nanofiber/PRP-scaffolds. Several physical and mechanical tests (weight loss measurement, surface wettability, porosity, microstructure observation via SEM photography, mechanical tests such as tensile strength, and Young modulus) and cellular assays (MTT assay and DAPI staining) were explored to assess the scaffolds capability to serve as neural guidance conduit. In this study, we hypothesized that conduits enriched with PRP may provide a better regenerative environment for nerve tissue repair. Results: This study suggests that GTNF/PRP incorporated scaffolds revealed better biological and physical properties than PLA only scaffolds. Conclusions: Results indicate that when GTNF/PRP is incorporated into the PLA scaffolds, resultant mechanical properties, porosity and cell attachment, and viability in vitro were better than pure PLA.

Biocompatible poly(vinyl alcohol)/poly (vinylpyrrolidone) iodine/poly(ethylene glycol) fibers containing (hydroxypropyl)methyl cellulose (HPMC) and aloe vera were successfully prepared by electrospinning their aqueous solution. Aloe vera which is known to be effective in the treatment of various wounds was added to the polymer solution. HPMC was added to the system as the water retention agent. The hybrid fiber mats were subjected to detailed analysis using a differential scanning calorimeter, a scanning electron microscope (SEM), and a Fourier transform infrared spectrometer. Images obtained from the SEM showed that the polymer fibers were linear, homogenous, and contained no beading. The fiber diameters ranged between 100 and 900 nm. It was seen that the electrospun mats obtained could potentially be used as a material for dressing wounds. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Due to the numerous advantages of nanofibers, there is a strong demand in various fields for nanofibrous structures fabricated by electrospinning. However, the process is currently beset by troublesome limitations with respect to geometric and morphological control of electrospun nanofibrous mats. This study presents a direct-write electrospinning process and apparatus with improved focusing and scanning functionalities for the fabrication of various patterned thick mats and nanofibrous patterns with high geometric fidelity, supported by a number of experimental results. Consequently, various patterned nanofibrous mats were fabricated using the developed method. Additionally, the fabricated mat was successfully used for cell patterning as a bioengineering application. The proposed method is expected to significantly improve the properties and functionalities of nanofibrous mats in a variety of applications.

Chitin nanofillers were incorporated in thermoplastic starch matrix by melt-mixing. Starch nanocomposites showed better mechanical properties than starch matrix. Starch nanocomposites presented good thermal stability. Materials with nanofibers showed better properties than those with nanocrystals. These nanocomposites contribute to a breakthrough in chitin applications.

Phase change materials (PCMs) are known to be excellent candidates for thermal energy storage in transient applications. However, enhancement of the thermal conductivity of a paraffin-based PCM is required for effective performance, particularly during solidification where diffusion is the dominant heat transfer mode. This study experimentally examines the effect that graphite nanofibers (GNFs), aspect ratio and power density have on both thermal storage and solidification time of a PCM which is embedded between two sets of aluminum fins. Additionally, a figure of merit is introduced in order to quantify the effectiveness of each of these three parameters with respect to solidification time. GNF enhancement was shown to reduce the maximum temperature in the thermal containment unit (TCU) by 48%. It was also found that for aspect ratios of 1, the GNF enhancement shortens solidification time by as much as 61% over the paraffin samples. This research indicates that GNF impregnation into phase change materials is an effective method for the enhancement of the thermal energy storage and the solidification of paraffin-based phase change materials.

Cinnamaldehyde, a natural preservative that can non-specifically deactivate foodborne pathogens, was successfully incorporated into fish skin gelatin (FSG) solutions and blow spun into uniform nanofibers. The effects of cinnamaldehyde ratios (5-30%,/FSG) on physicochemical properties of fiber-forming emulsions (FFEs) and their nanofibers were investigated. Higher ratios resulted in higher values in particle size and viscosity of FFEs, as well as higher values in diameter of nanofibers. Loss of cinnamaldehyde was observed during solution blow spinning (SBS) process and cinnamaldehyde was mainly located on the surface of resultant nanofibers. Nanofibers all showed antibacterial activity by direct diffusion and vapor release againstO157:H7, and. Inhibition zones increased as cinnamaldehyde ratio increased. Nanofibers showed larger inhibition effects than films prepared by casting method when.was exposed to the released cinnamaldehyde vapor, although films had higher remaining cinnamald...

The potential of nanoscaled cellulose and enzymatically phosphorylated derivatives as bio-adsorbents to remove metal ions (Ag(+), Cu(2+) and Fe(3+)) from model water and industrial effluents is demonstrated. Introduction of phosphate groups onto nanocelluloses significantly improved the metal sorption velocity and sorption capacity. The removal efficiency was considered to be driven by the high surface area of these nanomaterials as well as the nature and density of functional groups on the nanocellulose surface. Generally, in the solutions containing only single types of metal ions, the metal ion selectivity was in the order Ag(+)&gt;Cu(2+)&gt;Fe(3+), while in the case of mixtures of ions, the order changed to Ag(+)&gt;Fe(3+)&gt;Cu(2+), irrespective of the surface functionality of the nanocellulose. In the case of industrial effluent from the mirror making industry, 99% removal of Cu(2+) and Fe(3+) by phosphorylated nanocellulose was observed. The study showed that phosphorylated n...

New hybrid nanofibers prepared with chitosan (CTS), containing a total amount of polyethylene oxide (PEO) down to 3.6 wt.%, and silica precursors were produced by electrospinning. The solution of modified sol-gel particles contained tetraethoxysilane (TEOS) and the organosilane 3-glycidyloxypropyltriethoxysilane (GPTEOS). This is rending stable solution toward gelation and contributing in covalent bonding with chitosan. The fibers encompass advantages of biocompatible polymer template silicate components to form self-assembled core-shell structure of the polymer CTS/PEO encapsulated by the silica. Potential applicability of this hybrid material to bone tissue engineering was studied examining its cellular compatibility and bioactivity. The nanofiber matrices were proved cytocompatible when seeded with bone-forming 7F2-cells, promoting attachment and proliferation over 7 days. These found to enhance a fast apatite formation by incorporation of Ca 2+ ions and subsequent immersion in modified simulated body fluid (m-SBF). The tunable properties of these hybrid nanofibers can find applications as active biomaterials in bone repair and regeneration.

Microfibrillated cellulose nanofibers (MFC) provide strong reinforcement in polymer nanocomposites. In the present study, cellulosic wood fiber pulps are treated by endoglucanases or acid hydrolysis in combination with mechanical shearing in order to disintegrate MFC from the wood fiber cell wall. After successful disintegration, the MFC nanofibers were studied by atomic force microscopy (AFM). Enzyme-treatment was found to facilitate disintegration, and the MFC nanofibers produced also showed higher average molar mass and larger aspect ratio than nanofibers resulting from acidic pretreatment.

This paper reports on structural characterization and morphology of titanium dioxide (TiO 2 ) nanofibers prepared by electrospinning using a solution that contained poly(vinyl pyrrolidone) (PVP) and titanium(diisoproproxide) bis(2,4-pentanedionate) 75 wt.% in 2-propanol. TiO 2 nanofibers with diameters of 80-100 nm were successfully obtained from calcination of the as-spun TiO 2 /PVP composite nanofibers at above 300 • C in air for 3 h. The as-spun and calcined TiO 2 /PVP composite nanofibers were characterized by TG-DTA, Raman spectroscopy, XRD, SEM, AFM, and TEM. The results indicated a significant effect of calcination temperature on the crystalline phase in the form of either anatase or mixed anatase-rutile and the morphology of the nanofibers. The anatase-to-rutile transformation and the grain growth during the calcination of the electrospun TiO 2 /PVP composite nanofibers, as revealed by TEM, occurred simultaneously and affected each other. The rutile content was the highest (∼80%) at 800 • C, and it can be expected that the complete anatase-to-rutile transformation in the TiO 2 nanofibers would be above 800 • C.

ABOUT THIS BOOK:

During the past decade, research and development in the area of synthesis and applications of different nanostructured titanium dioxide have become tremendous. This book briefly describes properties, production, modification and applications of nanostructured titanium dioxide focusing in particular on photocatalytic activity. The physicochemical properties of nanostructured titanium dioxide are highlighted and the links between properties and applications are emphasized. The preparation of TiO2 nanomaterials, including nanoparticles, nanorods, nanowires, nanosheets, nanofibers, and nanotubes are primarily categorized by their preparation method (sol-gel and hydrothermal processes). Examples of early applications of nanostructured titanium dioxide in dye-sensitized solar cells, hydrogen production and storage, sensors, rechargeable batteries, electrocatalysis, self-cleaning and antibacterial surfaces and photocatalytic cancer treatment are reviewed. The review of modifications of TiO2 nanomaterials is mainly focused on the research related to the modifications of the optical properties of TiO2 nanomaterials, since many applications of TiO2 nanomaterials are closely related to their optical properties. Photocatalytic removal of various pollutants using pure TiO2 nanomaterials, TiO2-based nanoclays and non-metal doped nanostructured TiO2 are also discussed.

Designing scaffolds that can mimic native skeletal muscle tissue and induce 3D cellular alignment and elongated myotube formation remains an ongoing challenge for skeletal muscle tissue engineering. Herein, we present a simple technique to generate core-shell composite scaffolds for mimicking native skeletal muscle structure, which comprise the aligned nanofiber yarn (NFY) core and the photocurable hydrogel shell. The aligned NFYs are prepared by the hybrid composition including poly(caprolactone), silk fibroin, and polyaniline via a developed dry-wet electrospinning method. A series of core-shell column and sheet composite scaffolds are ultimately obtained by encapsulating a piece and layers of aligned NFY cores within the hydrogel shell after photo-cross-linking. C2C12 myoblasts are seeded within the core-shell scaffolds, and the good biocompatibility of these scaffolds and their ability to induce 3D cellular alignment and elongation are successfully demonstrated. Furthermore, the 3D elongated myotube formation within core-shell scaffolds is also performed after long-term cultivation. These data suggest that these core-shell scaffolds combine the aligned NFY core that guides the myoblast alignment and differentiation and the hydrogel shell that provides a suitable 3D environment for nutrition exchange and mechanical protection to perform a great practical application for skeletal muscle regeneration.

The fundamental properties of one-dimensional (1D) carbon nanostructures and their promising technological applications have stimulated significant research in different areas. Because of their outstanding electrical and mechanical properties, these nanostructures have emerged as a new class of sensor material with real potential for a variety of nano-electromechanical systems (NEMS). Several studies have shown that the performance of a NEMS device is significantly affected by the material properties of the nanostructures used to build it. For this reason, a section of this review is devoted to the synthesis and properties of 1D carbon nanostructures including nanotubes, nanofibers, and nanowires. Thereafter, some NEMS-based sensors using 1D carbon nanostructures are introduced and issues related to their fabrication processes are addressed. The goal of this brief review is to outline the benefits of the use of 1D carbon nanostructures, the current status of development and challenges to enable their widespread application as sensing elements in NEMS devices.

Nanoteknoloji ile ilgili çalışmalar son günlerde oldukça yoğundur. Geçtiğimiz günlerde 8-12 Haziran 2009 tarihleri arasında 5. Ulusal Nanobilim ve Teknoloji sempozyumu (Nanotr 5) Eskişehir’ de gerçekleştirilmiştir [1]. 10-13 Ağustos 2009 tarihleri arasında da İTÜ’ de Nanomats Uluslar arası sempozyumu düzenlenmesi planlanmaktadır. Ülkemizde başta UNAM olmak üzere, birçok Üniversite ve kuruluş bu konu ile ilgili oldukça fazla uğraş vermektedir. Henüz Nanoteknoloji ile ilgili çalışmalar emekleme seviyesinde olmasına karşın, tüm bilim insanları yeni nano-teknolojik ürün oluşturma gayreti içindedirler. Akıllı - kendini temizleyen boyalar, kir tutmayan çantalar, koku yaymayan çoraplar, yapay organ, nano-cip, kırışmayan ve ütü gerektirmeyen elbiseler sadece bunlara verebileceğimiz birkaç örnektir. Stratejik öneme sahip, son derece kullanışlı ve dayanıklı karbon fiber mikro elektrot (KFME) malzeme (7 μ çapında) ve bunların üzerine elektrokimyasal metotlarla kaplanmış π - konjuge bağ içeren monomerler (pirol, karbazol, tiyofen, anilin vb.) çalışma konularımı oluşturmaktadır. Elde edilen filmlerin ve kompozit malzemelerin çekme – germe ve kopma mukavemeti, film kalınlığı ve uygulama alanlarına (elektrokimyasal empedans spektroskopisi (EIS) ve biyosensör uygulamalar) ne derece sahip olup olmadıkları değişik karakterizasyon yöntemleri ile test edilmektedir. Bunlar arasında, (Döngülü voltametre (DV), FTIR reflektans spektrofotometre ve reflektans UV-vis spektrofotometrisi, Taramalı elektron mikroskop (TEM) ve Atomik kuvvet mikroskop (AKM)) sayılabilir. Elde edilen ince filmler nanokompozit malzeme olarak, (biyo) sensör ve EIS konularında detaylıca çalışılmaktadır.

Presenting the latest coverage of the fundamentals and applications of nanofibrous materials and their structures for graduate students and researchers, this book bridges the communication gap between fiber technologists and materials scientists and engineers. Featuring intensive coverage of electroactive, bioactive and structural nanofibers, it provides a comprehensive collection of processing conditions for electrospinning and includes recent advances in nanoparticle-/nanotube-based nanofibers. The book also covers mechanical properties of fibers and fibrous assemblies, as well as characterization methods.

Cellulose acetate (CA) has been a material of choice for spectrum of utilities across different domains ranging from high absorbing diapers to membrane filters. Electrospinning has conferred a whole new perspective to polymeric materials including CA in the context of multifarious applications across myriad of niches. In the present review, we try to bring out the recent trend (focused over last five years' progress) of research on electrospun CA fibers of nanoscale regime in the context of developmental strategies of their blends and nanocomposites for advanced applications. In the realm of biotechnology, electrospun CA fibers have found applications in biomolecule immobilization, tissue engineering, bio-sensing, nutraceutical delivery, bioseparation, crop protection, bioremediation and in the development of anti-counterfeiting and pH sensitive material, photocatalytic self-cleaning textile, temperature-adaptable fabric, and antimicrobial mats, amongst others. The present review discusses these diverse applications of electrospun CA nanofibers.

Electrospinning has been recognized as a simple and versatile method for fabrication of polymer nanofibers. Various polymers that include synthetic, natural, and hybrid materials have been successfully electrospun into ultrafine fibers. The inherently high surface to volume ratio of electrospun fibers can enhance cell attachment, drug loading, and mass transfer properties. Drugs ranging from antibiotics and anticancer agents to proteins, DNA, RNA, living cells, and various growth factors have been incorporated into electrospun fibers. This article presents an overview of electrospinning techniques and their application in drug delivery.

ABSTRACT This article verifies the hysteresis phenomenon in heat–voltage curves of polypyrrole-coated electrospun nanofibrous and regular fibrous mats. A third-order polynomial model fits the heat–voltage data better than a second-order polynomial model. It was also observed that the hysteresis loop area of nanofibrous and regular fibrous mats increases with decreasing fiber diameter. Moreover, the curvature of the hysteresis loops is significantly affected by the fiber diameter. In fact, the slope of the curvatures increases with decreasing fiber diameter.

Infections caused by microorganisms like bacteria, fungi, etc. are the main obstacle in healing processes. Conventional antibacterial administration routes can be listed as oral, intravenous/intramuscular, topical and inhalatory. These kinds of drug administrations are faced with critical vital issues such as; more rapid delivery of the drug than intended which can result inbacterial resistance, dose related systemic toxicity, tissue irritation and finally delayed healing process that need to be tackled. Recently, studies have been focused on new drug delivery systems, overcoming resistance and toxicological problems and finally localizing the molecules at the site of action in a proper dose. In this regard, many nanotechnological approaches such as nanoparticulate therapeutic systems have been developed to address accompanying problems mentioned above.Among them, drug loaded electrospun nanofiberspropose main advantages like controlled drug delivery, high drug loading capacity, hig...

In this work, the technology of nano and micro-scale particle reinforcement concerning various polymeric fibre-reinforced systems including polyamides (PA), polyesters, polyurethanes, polypropylenes and high performance/temperature engineering polymers such as polyimide (PI), poly(ether ether ketone) (PEEK), polyarylacetylene (PAA) and poly p-phenylene benzobisoxazole (PBO) is reviewed. When the diameters of polymer fibre materials are shrunk from micrometers to submicrons or nanometers, there appear several unique characteristics such as very large surface area to volume ratio (this ratio for a nanofibre can be as large as 10 3 times of that of a microfibre), flexibility in surface functionalities and superior mechanical performance (such as stiffness and tensile strength) compared with any other known form of the material. However, nanoparticle reinforcement of fibre reinforced composites has been shown to be a possibility, but much work remains to be performed in order to understand how nanoreinforcement results in dramatic changes in material properties. The understanding of these phenomena will facilitate their extension to the reinforcement of more complicated anisotropic structures and advanced polymeric composite systems.

Most of the phenomena in life, such as heat transfer, wave propagation, thermoelectricity, sheet materials, multifunctional material properties, etc., can be expressed through mathematical equations or partial differential equations (PDEs). However, with complex differential equations, it is difficult or impossible to find solutions, especially differential equations for complex problems such as solid-liquid interactions, mechanical-thermal-electrical environments, and functional material plate environments in the multiphysics environment, etc. Since then, many numerical methods have been researched and developed to find approximate solutions to partial differential equations. Today, the finite element method (FEM) is the most widely used and effective among the commonly used numerical methods. However, with the continuous emergence of new complex problems in science and technology, especially problems in the multiphysics environment in sheet-material structures, the finite element method has revealed new challenges. There are certain limitations related to the element technique and the weak form discretization of the problem of sheet structure with many different degrees of freedom, significantly affecting the accuracy and efficiency of calculations. Therefore, it is always important to propose improvements to the traditional finite element method and the optimal method algorithm to meet the increasing requirements in the behavior analysis of sheet materials. This research direction is always topical and has received the attention of scientists around the world for many decades.

One-dimensional (1-D) nanostructures have attracted enormous research interest due to their unique physicochemical properties and wide application potential. These 1-D nanofibers are being increasingly applied to biomedical fields owing to their high surface area-to-volume ratio, high porosity, and the ease of tuning their structures, functionalities, and properties. Many biomedical nanofiber reviews have focused on tissue engineering and drug delivery applications but have very rarely discussed their use as wound dressings. However, nanofibers have enormous potential as wound dressings and other clinical applications that could have wide impacts on the treatment of wounds. Herein, the authors review the main fabrication methods of nanofibers as well as requirements, strategies, and recent applications of nanofibers, and provide perspectives of the challenges and opportunities that face multifunctional nanofibers for active therapeutic applications.

Electrospinning is a versatile technique for generating a mat of continuous fibers with diameters from a few nanometers to several micrometers. The diversity of electrospinnable materials, and the unique features associated with electro-spun fibers make this technique and its resultant structures attractive for applications in the biomedical field. This article presents an overview of this technique focusing on its application for tissue engineering. In particular, the advantages and disadvantages of using an electrospinning mat for biomedical applications are discussed. It reviews the different available electrospinning configurations, detailing how the different process variables and material types determine the obtained fibers characteristics. Then a description of how nanofiber based scaffolds offer great promise in the regener-ation or function restoration of damaged or diseased bones, muscles or nervous tissue is reported. Different methods for incorporating active agents on nanofibers and controlling their release mechanisms are also reviewed. The review concludes with some personal perspectives on the future work to be done in order to include electrospinning technique in the industrial development of biomedical materials.

Electrospinning is a widely used technique to produce continuous polymeric fibers ranging from 2 nm to several micrometers. This technique is not only employed in research laboratories, but it is also increasingly being applied in different industrial fields in the last few decades as a highly versatile and cost-effective technology. Compared to conventional techniques for fiber fabrication, electrospinning can fabricate fibers in a more desirable size (e.g., nanoscale). Nanofibers are generated by the application of a strong electric field on polymer solution. Over the years, more than 200 polymers have been electrospun for various applications. In this review, our aim was to present an overview of the electrospinning technique and its potential applications. We covered the basic principles of the electrospinning technique and parameters which significantly affect the fiber morphology. The most recent work on electrospinning nanofibers for blending polymers, filtration, energy, sensing and biomedical applications was also presented in this review.

The ultimate goal of tissue engineering is to replace damaged tissues by applying engineering technology and the principles of life sciences. To successfully engineer a desirable tissue, three main elements of cells, scaffolds and growth factors need to be harmonized. Biomaterial-based scaffolds serve as a critical platform both to support cell adhesion and to deliver growth factors. Various methods of fabricating scaffolds have been investigated. One recently developed method that is growing in popularity is called electrospinning. Electrospinning is known for its capacity to make fibrous and porous structures that are similar to natural extracellular matrix (ECM). Other advantages to electrospinning include its ability to create relatively large surface to volume ratios, its ability to control fiber size from micro-to nano-scales and its versatility in material choice. Although early work with electrospun fibers has shown promise in the regeneration of certain types of tissues, further modification of their chemical, biological and mechanical properties would permit future advancements. In this paper, current approaches to the development of modular electrospun fibers as scaffolds for tissue engineering are discussed. Their chemical and physical characteristics can be tuned for the regeneration of specific target tissues by co-spinning of multiple materials and by post-modification of the surface of electrospun fibers. In addition, topology or structure can also be controlled to elicit specific responses from cells and tissues. The selection of proper polymers, suitable surface modification techniques and the control of the dimension and arrangement of the fibrous structure of electrospun fibers can offer versatility and tissue specificity, and therefore provide a blueprint for specific tissue engineering applications.

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.

Nanofibers have superior physical and mechanical properties. Although nanofibers can be produced by several methods, the electrospinning is predominant method in terms of simplicity, fiber diameter, flexibility and morphology. Moreover, usage nanofibers are generally produced as non-woven webs by electrospinning. This shape of production limits usage areas of nanofibers. Therefore, researchers have been working on electrospinning of nanofibers into yarns. The main aims of these studies are alignment and twisting of nanofibers. The usage areas of nanofibers will be increased by converting them into yarns from webs. Nanofibers in yarn formation can be used in several applications especially woven and knitted fabrics like convention yarns. The aim of this study is to analyze the studies about electrospun nanofiber yarn production in terms of twisting and winding mechanisms developments by years and also working principles and parameters of the electrospinning setups that are related to production of nanofiber yarn in the literature are compared. These studies are divided into two classes as discontinuous and continuous, both of them are divided into sub groups twisted and non-twisted systems. When nanofiber yarn production studies by electrospinning method are examined, it can be said that the continuous methods are advantageous compared to the discontinuous methods in terms of production speed. Twisted systems are more attractive because they give strength to the nanofiber yarn. Needless type feeders are more suitable for high speed production than needle type feeders that are used to decrease complexity of the process. In recent years, funnels, discs and cylinder types of twisting units have been preferred due to the advantages of easy installation and twisting control. As a result, systems that produce nanofiber yarns by electrospinning method are trending to industrial production that means they are focused on twisted and continuous nanofiber yarns.

The present study describes the processing and mechanical characterization of S-2 glass fiber with and without interleaved Ethyl Orthosilicate (TEOS) chemically engineered glass nanofibers manufactured using electrospinning technique with resin EPON 862 with EPIKURE curing agent W. The manufactured electrospun TEOS nanofiber were sintered to evaporate ethanol and reduce the fiber diameter so as to increase the surface area. The heated Vacuum assisted resin transfer molding (H-VARTM) method was used to fabricate the combined panel using same resin and equal flow and specimen were cut using the water jet machine as per the standards. Tension, compression, in plane shear, interlaminar shear and iosipecu test were conducted as per the accepted ASTM test standards. The mechanical properties strength, modulus, Poisson's ratio, shear modulus, fiber volume fraction ratios and densities are measured and corresponding modes of failure have been studied and compared with each other. The S-2 glass fibers with Electrospun TEOS nanofiber composite have shown significant improvement in the in plane shear strength and modulus and slightly improvement in the tensile properties. However lower the compression strength and modulus as well as shear modulus. Due to pre bend in the plies of the glass fiber and fold over elastic sizing are the possible reasons for reduction of compression properties. The predicted values of the elastic constant using simplified micormechanics equation of the composite are verified with experimental result that matches and have shown the significant improvement in the in plane shear strength of the composite that will help to improve the delaimination of the composite.

Currently the applications of silver nanoparticles (Ag NPs) are gaining overwhelming response due to the advancement of nanotechnology. However, only limited information is available with regard to their toxicity mechanism in different species. It is very essential to understand the complete molecular mechanism to explore the functional and long term applications of Ag NPs. Ag NPs could be toxic at cellular, subcellular, biomolecular, and epigenetic levels. Toxicity effects induced by Ag NPs have been evaluated using numerous in vitro and in vivo models, but still there are contradictions in interpretations due to disparity in methodology, test endpoints and several other model parameters which needs to be considered. Thus, this review article focuses on the progressive elucidation of molecular mechanism of toxicity induced by Ag NPs in various in vitro and in vivo models. Apart from these, this review also highlights the various ignored factors which are to be considered during toxicity studies.