Polyacrylonitrile belongs to the most often used precursors for carbon fibers. Using electrospinning, polyacrylonitrile nanofiber mats can be prepared and afterwards stabilized and carbonized to prepare carbon nanofiber mats which, by adding other materials, will be useful for several applications. One of these materials is TiO2, which has photocatalytic properties and can thus be used as a photocatalyst for photodegradation of dyes. Here, we report on a detailed study of electrospinning, stabilization, and carbonization of electrospun polyacrylonitrile/TiO2 mats with varying TiO2 content. Depending on the amount of TiO2 in the nanofibers, the fiber morphology changes strongly, indicating an upper limit for the preparation of carbon/TiO2 nanofibers with smooth surface, but offering an even increased inner surface of the rougher carbon/TiO2 nanofibers with increased TiO2 content due to better maintenance of the fibrous structure during stabilization.

Nanofi brous mats can be used as a substrate for eukaryotic cell growth in biotechnology, tissue engineering, etc. Several adherent cells (e.g. human fi broblasts) have been shown to grow well on fi ne fi bres. For most applications, it is necessary to sterilize nanofi brous mats before adding the cells. Another possibility would be the addition of antibiotics and antimycotics to the cell culture medium to prevent microbial infection. However, antibiotics are disadvantageous since they might promote the growth of resistant bacteria in possible future medical applications of nanofi brous mats. Possible sterilization techniques include autoclaving, UV-sterilization, ozone treatment, heat sterilization and other techniques which usually necessitate more expensive equipment, such as gamma irradiation. Systematic examinations of the infl uence of diff erent sterilization techniques on the cell growth on nanofi brous mats have not yet been reported in the literature. Here, we report on the fi rst experimental investigations of the eff ect of sterilization with diff erent methods on the properties of polyacrylonitrile (PAN)/gelatine nanofi brous mats, and the resulting growth and adhesion of Chinese hamster ovary cells. While all techniques under investigation yielded sterile nanofibrous mats, autoclaving and heat sterilization change the PAN/gelatine fi bre morphology. Ozone, on the other hand, modifi es the pH value of the culture medium and partly impedes cell adhesion. UV sterilization also suggests a chemical modifi cation of the nanofi brous mat. Unexpectedly, heat sterilization resulted in the highest amount of adherent Chinese hamster ovary cells grown on PAN/gelatine nanofi brous mats in spite of gelatine melting.

Textile-based dye-sensitized solar cells (DSSCs) can be created by building the necessary layers on a textile fabric or around fibers which are afterwards used to prepare a textile layer, typically by weaving. Another approach is using electrospun nanofiber mats as one or more layers. In this work, electrospun polyacrylonitrile (PAN) nanofiber mats coated by a conductive polymer poly(3,4-ethylenedioxythiopene) polystyrene sulfonate (PEDOT:PSS) were used to produce the counter electrodes for half-textile DSSCs. The obtained efficiencies were comparable with the efficiencies of pure glass-based DSSCs and significantly higher than the efficiencies of DSSCs with cotton based counter electrodes. The efficiency could be further increased by increasing the number of PEDOT:PSS layers on the counter electrode. Additionally, the effect of the post treatment of the conductive layers by HCl, acetic acid, or dimethyl sulfoxide (DMSO) on the DSSC efficiencies was investigated. Only the treatment by HCl resulted in a slight improvement of the energy-conversion efficiency.

Pleurotus ostreatus is a well-known edible mushroom species which shows fast growth. The fungus can be used for medical, nutritional, filter, or packaging purposes. In this study, cultivation experiments were carried out with Pleurotus ostreatus growing on polyacrylonitrile (PAN) nanofiber mats in the presence of saccharose and Lutrol F68. The aim of this study was to find out whether modified PAN nanofiber mats are well suited for the growth of fungal mycelium, to increase growth rates and to affect mycelium fiber morphologies. Our results show that Pleurotus ostreatus mycelium grows on nanofiber mats in different morphologies, depending on the specific substrate, and can be used to produce a composite from fungal mycelium and nanofiber mats for biomedical and biotechnological applications.

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