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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.

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For more information refer to www.gelifesciences.com/handbooks 2-D Electrophoresis Principles and Methods GE Healthcare Life Sciences 2-D Electrophoresis using immobilized pH gradients Principles and Methods 80-6429-60 Affinity Chromatography

A prototype of a newly developed apparatus for measuring cell growth characteristics of suspension cells in micro titre plates over a period of time was examined. Fully automated non-invasive cell counts in small volume cultivation vessels, e.g. 96 well plates, were performed with the Cellscreen system by Innovatis AG, Germany. The system automatically generates microscopic images of suspension cells which had sedimented on the base of the well plate. The total cell number and cell geometry was analysed without staining or sampling using the Cedex image recognition technology. Thus, time course studies of cell growth with the identical culture became possible. Basic parameters like the measurement range, the minimum number of images which were required for statistically reliable results, as well as the influence of the measurement itself and the effect of evaporation in 96 well plates on cell proliferation were determined. A comparison with standard methods including the influence of the cultured volume per well (25 mul to 200 mul) on cell growth was performed. Furthermore, the toxic substances ammonia, lactate and butyrate were used to show that the Cellscreen system is able to detect even the slightest changes in the specific growth rate.