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Department of Cell Biology and Applied Virology
25
Total Impact Points
8
Members
Department of Biophysics and Cryotechnology
29
Total Impact Points
5
Members

Publication History View all

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    ABSTRACT: Cultivation and proliferation of stem cells in three-dimensional (3-D) scaffolds is a promising strategy for regenerative medicine. Mesenchymal stem cells with their potential to differentiate in various cell types, cryopreserved adhesion-based in fabricated scaffolds of biocompatible materials can serve as ready-to-use transplantation units for tissue repair, where pores allow a direct contact of graft cells and recipient tissue without further preparation. A successful cryopreservation of adherent cells depends on attachment and spreading processes that start directly after cell seeding. Here, we analyzed different cultivation times (0.5, 2, 24 h) prior to adhesion-based cryopreservation of human mesenchymal stem cells within alginate-gelatin cryogel scaffolds and its influence on cell viability, recovery and functionality at recovery times (0, 24, 48 h) in comparison to non-frozen control. Analysis with confocal laser scanning microscopy and scanning electron microscopy indicated that 2 h cultivation time enhanced cryopreservation success: cell number, visual cell contacts, membrane integrity, motility, as well as spreading were comparable to control. In contrast, cell number by short cultivation time (0.5 h) reduced dramatically after thawing and expanded cultivation time (24 h) decreased cell viability. Our results provide necessary information to enhance the production and to store ready-to-use transplantation units for application in bone, cartilage or skin regenerative therapy.
    Journal of Materials Science Materials in Medicine 12/2013; 25(3). DOI:10.1007/s10856-013-5108-x
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    ABSTRACT: Therapeutic proteins are an integral part of today's pharmaceutical practice, but they still present challenges from the drug delivery point of view. In this work we study a new approach based on hard templating for fabrication of microparticles composed of pure insulin that may enable effective delivery, for instance pulmonary delivery. The approach is both simple and versatile: the protein particles are prepared by selective precipitation into porous CaCO3 microtemplates, followed by full decomposition of the template at the isoelectric point of the protein (pH 5.2). Control over the main material parameters (mechanical properties, porosity, morphology, and stability at physiological conditions) are critical for the envisioned application in drug delivery. We demonstrate that these critical parameters can be significantly tuned by a slight final pH variation around the isoelectric point (pH range 4-6) and by the denaturation degree of insulin. Electrostatic interactions and inter-protein crosslinking in the protein particles as well as their internal structure are considered to explain the variation in the particle properties. We explore the particle properties parameters using atomic force microscopy (AFM), optical microscopies, CD, etc. Finally, we studied phagocytic clearance the of protein particles in vitro to explore possible enhancements of particle fabrication to improve insulin delivery efficiency by inhalation.
    Acta biomaterialia 11/2013; DOI:10.1016/j.actbio.2013.11.011
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    ABSTRACT: The enzyme horseradish peroxidase has been immobilized on nanoelectrode arrays by alternating current dielectrophoresis. Preservation of its enzymatic function after field application was demonstrated by oxidizing dihydrorhodamine 123 with hydrogen peroxide as co-oxidant to create its fluorescent form, rhodamine 123. Localization of the fluorescently labeled enzyme and its product was conducted by fluorescence microscopy. Nanoelectrodes were prepared as tungsten pins arranged in square arrays. Experimental parameters for dielectrophoretic immobilization were optimized for even enzyme distribution and for enzymatic efficiency. Enzyme activity was quantified by determination of fluorescence intensities of immobilized enzyme molecules and of rhodamine 123 produced. These results demonstrate that DEP can be applied to immobilize enzyme molecules while retaining their activity and rendering any chemical modifications unnecessary. This introduces a novel way for the preparation of bioactive surfaces for processes such as biosensing.
    Electrophoresis 11/2013; DOI:10.1002/elps.201300447

Information

  • Address
    Ensheimer Straße 48, 66386 St. Ingbert, Sankt Ingbert, Germany
  • Head of Institution
    Prof. Dr. Günter Fuhr
  • Website
    http://www.ibmt.fraunhofer.de/
  • Phone
    +49 (0) 6894 980 - 0
  • Fax
    +49 (0) 6894 980 - 400
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Top publications last week by downloads

 
The International journal of developmental biology 01/2012; 56(1-3):117-25. DOI:10.1387/ijdb.113440sm
8 Downloads
 
Biomedizinische Technik 01/2014; 59(s1):S1089.
8 Downloads

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