Tungsten oxide (WO 3 ) nanofibers with shapes ranging from cylindrical to ribbon-like were prepared by annealing electrospun polyvinylpyrrolidone/ammonium metatungstate (PVP/AMT) fibers. Formation of periodically folded "zigzag" patterns in PVP/AMT and WO 3 ribbon-like fibers was observed for the first time at the initial stage of the electrospinning process on the surface of a stationary substrate. Among methods tested (capillary needle, needleless dc-and ac-electrospinning), only the capillary needle dc-electrospinning process was effective in producing ribbon-like fiber structures. Annealing of such PVP/AMT fibers at 500 C in air led to the formation of 80 AE 10 nm thick WO 3 ribbons with a width-tothickness ratio of up to 50 : 1. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Raman spectroscopy were used to analyze the material. Analyses revealed that regardless the fiber's shape, the annealed oxide fibers were polycrystalline with a grain size of 60 AE 30 nm and consisted of the monoclinic phase of WO 3 . When compared to cylindrical fibers, the ribbon-like WO 3 nanofibers exhibited higher porosity but lower mechanical strength with increased width of the ribbon-like structure. Fig. 7 XPS (W4f, C1s, O1s, and N1s) spectra of (a) as prepared PVP/AMT ribbon-like nanofibers and (b) the resulting WO 3 fibers after thermal processing for 3 h at 500 C in the air; (c) FTIR spectra of PVP/AMT (top) and annealed WO 3 (bottom) fibers.This journal is

The biological (antiviral) activity of a dried purified extract of Stevia was evaluated in vitro. Tests were performed using Teschen disease virus, infectious rhinotracheitis virus, and human coronavirus.

In this work, we report the electrospinning and mechano-morphological characterizations of scaffolds based on blends of a novel poly(ester urethane urea) (PHH) and poly(dioxanone) (PDO). At the optimized electrospinning conditions, PHH, PDO and blend PHH/PDO in Hexafluroisopropanol (HFIP) solution yielded bead-free non-woven random nanofibers with high porosity and diameter in the range of hundreds of nanometers. The structural, morphological, and biomechanical properties were investigated using Differential Scanning Calorimetry, Scanning Electron Microscopy, Atomic Force Microscopy, and tensile tests. The blended scaffold showed an elastic modulus (~5 MPa) with a combination of the ultimate tensile strength (2 ± 0.5 MPa), and maximum elongation (150% ± 44%) in hydrated conditions, which are comparable to the materials currently being used for soft tissue applications such as skin, native arteries, and cardiac muscles applications. This demonstrates the feasibility of an electrospun PHH/PDO blend for cardiac patches or vascular graft applications that mimic the nanoscale structure and mechanical properties of native tissue.

Carbon nanostructures, e.g., nanotubes, fullerenes, carbon blacks, etc., are being extensively explored for numerous biomedical applications. The most of such studies, however, deal with carbon nanotubes, and comparatively less is known on the biomedical potential of other nanosize carbon particles. In the present work, carbon and metal/carbon core/shell spherical nanoparticles have been prepared using the decomposition of monosaccharide-based compositions under hydrothermal conditions with or without the presence of metal seed particles. The effects of different process conditions on the particle size, structure, and composition have been examined using TEM, XRD, UV-Vis, FTIR and Raman spectroscopies. The nearly perfect spherical particles with the dimensions in the range of 20 – 100 nm have been obtained depending on the process parameters such as precursor concentration, presence of seed particles and polymeric additives, process temperature and time. The particles prepared with 5 – 20 nm gold seeds clearly showed the core/shell structure with the thickness of carbon shell in the range of 10 – 50 nm. The FTIR experiments have indicated a strong effect of the processing conditions on the chemical activity of nanoparticle surfaces in the attachment of the additional surface functional groups and organic molecules. It has been found that the both hydrothermally prepared carbon and metal/carbon core/shell nanoparticles possess very good dispersibility and stability in the both water and simulated body fluids in the most of experiments. The particles have been successfully functionalized with several molecules such as polyethyleneglucol and biotin. Selected samples of well-dispersed carbon nanospheres with different concentrations have been tested for their interaction with several cultured cell lines including epidermal keratinocytes, fibroblasts, and dog macrophages.