Papers by Keyword: Nanofiber

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Authors: Natthan Charernsriwilaiwat, Theerasak Rojanarata, Tanasait Ngawhirunpat, Praneet Opanasopit
Abstract: The aim of this study was to investigate the antioxidant activities of chitosan acetate (CS-acetate), chitosan hydroxybenzotriazole (CS-HOBt), chitosan thiamine pyrophosphate (CS-TPP) and chitosan ethylenediaminetetraacetic acid (CS-EDTA) nanofiber mats. Chitosan was dissolved with hydroxybenzotriazole (HOBt), thiamine pyrophosphate (TPP) and ethylenediaminetetraacetic acid (EDTA) in distilled water. These chitosan aqueous salts were blended with polyvinyl alcohol (PVA) at volume ratio 30/70 chitosan salts/PVA and prepared to nanofibers via electrospinning process. The morphology of electrospun chitosan aqueous salts based nanofiber mats were observed under scanning electron microscope (SEM). The antioxidant activities were determined employing various established in vitro system such as superoxide, hydroxyl radicals scavenging and metal ion chelating compared with pure PVA nanofiber mats. The results exhibited that the electrospun chitosan aqueous salts based nanofiber mats showed the different antioxidant activity depended on salt forms. Among the salt forms, CS-acetate nanofiber mats showed the highest superoxide radical scavenging effect while CS-HOBt nanofiber mats (IC50 = 7.53 mg/mL) showed the highest hydroxyl radical scavenging effect. For the metal ion chelating activity, CS-EDTA nanofiber mats showed the highest chelating activity (IC50 = 1.07 mg/mL). In summary, the antioxidant chitosan aqueous salt based nanofiber mats have potential for use in pharmaceutical applications.
Authors: Xin Zhang, Min Wang, Xiao Yan Yuan, Jia Chen Kang
Abstract: Electrospinning is investigated by many groups around the world for constructing fibrous tissue engineering scaffolds. Incorporating biomolecules such as growth factors in fibers is becoming common for enhancing the biological performance of electrospun scaffolds. However, biomolecules may lose bioactivity if they are exposed to organic solvent during electrospinning. In emulsion electrospinning, an aqueous biomolecule solution is emulsified and water-in-oil emulsions are then electrospun into core-shell structured fibers, with biomolecules being contained in the core of fibers, which helps to avoid biomolecule-solvent contact and also reduce the initial burst release. In this investigation, for a comparative study, poly (L-lactic acid) was made into solid and core-shell structured fibers via conventional electrospinning and emulsion electrospinning, respectively. The two electrospinning techniques and resultant fibers were compared in terms of processing parameters (polymer concentration, applied voltage, working distance, etc.) and fiber characteristics (morphology, diameter, structure, etc.). Solvent properties such as conductivity and volatility affected fiber morphology and diameter. The polymer concentration range usable for emulsion electrospinning was narrower than that for conventional electrospinning owing to changes in viscosity.
Authors: Li Guo, Yuan Bao Sun, Jian Qiang Hu, Zhi Jie Huang
Abstract: We described a facile approach to carrying out secondary doping of polyaniline nanofibers. SEM, UV-VIS-NIR and XRD techniques were used to characterize the secondary doping and de-doping of polyaniline nanofibers. The conductivity of secondary doping and de-doping of polyaniline nanostructure with m-cresol is higher than before secondary doping of it accompany with keeping nanostructure. A new approach to improving electric performance of polyaniline nanostructure was provided.
Authors: Bo Yuan, Qun Feng Liu, Cai Lin, Xiao Feng Chen
Abstract: In this paper, a high order strain gradient (HSGE) model is constructed to predict the bending size dependence of the elastic property of nanofibers under three-point tests. The model can be applied to explain the size dependency in bending test for polymeric nanofibers.
Authors: Hai Yan Kong, Ji Huan He
Abstract: This paper suggests a new method for fabrication of nanofibers with polymer liquid membrane, which is produced by a metal ring rotating through the polymer solution. The thickness of the produced membrane is thin and suitable for nanomaterial fabrication. In this paper the membrane is to form a polymer bubble by blowing air under the presence of a high electronic field, and multiple jets eject when the bubble is ruptured. The effect of applied voltage on the fiber diameter is studied.
Authors: W. Han, Ming Xia Lu, H. Wang, G. Liu
Abstract: Water contaminated by heavy metals remains a serious environmental and public health problem. The toxic effects of heavy metals on the biosphere have been demonstrated by a number of studies. Since the main sources of heavy metals for humans are water and food, the monitoring of the heavy metals content in natural water is of paramount importance. Diverse technologies have been used to reduce the contents of heavy metals in water. Recently, adsorption methods have been widely used because of their low cost. The novel nano-water-purifying material used in our work is composed of AlO(OH) nanoparticles loaded onto glass fibre and supported by active carbon felt. The Al nano-powder starting material, was prepared using an electric explosive technique. The products were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, and BET techniques. It was found that the particles consisted of AlO(OH) nanofibres of pure boehmite structure. They exhibited a surface area of 431.7 m2 / g. The composite material was found to be effective in removing cadmium from dilute aqueous solutions and could find broad application in heavy metal removal.
Authors: Ming Tian, You Ping Wu, Wen Li Liang, Li Jun Cheng, Li Qun Zhang
Authors: Mahboubeh Maleki, Mohammad Amani-Tehran, Masoud Latifi, Sanjay Mathur
Abstract: The demand for novel antibiotic-loaded electrospun nanofibrous structures has increased extremely in the recent years and has engaged the interests of scientists and engineers into a blend configuration of antibiotic drug and biocompatible polymers due to their unique applications in future of better therapeutic effect, reduced toxicity and sustained local antibiotic release over a period of time. One method to produce these antibiotic-loaded networks is by electrospinning process. However, it is very important to know structural characteristics and morphology of nanofibers for controlling the performance of the yields. In this paper, fabrication of electrospun nanofibers suited for antibiotic delivery system is investigated based on tetracycline hydrochloride as the antibiotic drug and poly (lactic-co-glycolic acid) as the biodegradable polymeric matrix. Furthermore, the effect of material and process parameters on morphology and release behavior of produced nonwovens is investigated. The efficacy of the medicated scaffolds using a static system for bacterial growth on agar plates was also proved.
Authors: Hang Jun Ding, Zhou Yang, Huai Yang, Mei Xiang Wan
Abstract: PANI nanofibers with a really nanoscaled diameter of 20 ~ 30 nm and a high conductivity of 100 S/cm were successfully prepared by using FeCl3 · 6H2O as oxidant at the acidic dopant-free. Compared with other synthetic methods for nanostructures, this approach is most simple and cheap because of FeCl3 · 6H2O having two-function of oxidant and dopant at the same time, resulting in further simplifying reaction reagents. Characterizations of UV-visible, FTIR spectra, XRD as well as conductivity measured by four-probe method definitely proved the nanofibers oxidized by FeCl3 as oxidant at dopant-free are identical to the emeraldine salt form of PANI, although without external acidic dopant, and Cl- anion is incorporated the PANI main chain as counter-ion.
Authors: Ke Han, Jing Ping Chen
Abstract: Large amount of research has been undertaken on the effects of conventional thermomechanical treatment and chemistry variations on the mechanical properties of nanostructured bulk materials developed for wire rod and sheet products. The thermomechanical treatments are selected to refine as much as possible the microstructure to achieve high strength. In most of the cases, the alloy additions are deliberated added to be beneficial to the mechanical properties of the nanostructured materials, especially the tensile strength. In addition to refine the microstructure, both the thermomechanical treatments and chemistry variations may also alter the shape and distribution of the strengthening phases. This article describes the nanostructured composites with face-centered cubic (fcc) copper or body-centered cubic (bcc) ferrite as matrix and discusses several factors that affect the mechanical strength of such materials.
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