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  • 1
    Electronic Resource
    Electronic Resource
    Evaluation of membranes for use in on-line cell separation during mammalian cell perfusion processes (1994)
    Springer
    Cytotechnology 15 (1994), S. 243-251 
    Details
    ISSN: 1573-0778
    Keywords: Hybridomate ; monoclonal antibody ; perfusion ; microfiltration ; membrane ; fouling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In this study two microporous hollow fibre membranes were evaluated for their use as cell retention device in continuous perfusion systems. A chemically modified permanent hydrophillic PTFE membrane and a hydrophilized PP membrane were tested. To investigate the filtration characteristics under process conditions each membrane was tested during a long term perfusion cultivation of a hybridoma cell line. In both cultivations the conditions influencing membrane filtration (e.g. transmembrane flux) were kept constant. Filtration behaviour was investigated by monitoring transmembrane pressure and protein permeability. Transmembrane pressure was measured on-line with an autoclavable piezo-resistive pressure sensor. Protein permeability was determined by quantitative evaluation of unreduced, Coomassie stained SDS-PAGE. The membrane fouling process influences the filtration characteristics of both membranes in a different way. After fermentation the PP membrane was blocked by a thick gel layer located in the big outer pores of the asymmetric membrane structure. The hydraulic resistance was higher but the protein permeability was slightly better than of the PTFE membrane. For this reason the PP membrane should be preferred. On the other hand, transmembrane pressure decreases slower when the PTFE membrane is used, which favours this membrane for long term cultivations, especially when low molecular weight proteins (〈30 KD) are produced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00762399
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A direct computer control concept for mammalian cell fermentation processes (1994)
    Springer
    Cytotechnology 15 (1994), S. 271-279 
    Details
    ISSN: 1573-0778
    Keywords: Bioreactor ; control ; computer ; fermentation ; perfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In the last 10 years, new assignments and the special demands of mammalian cells to the culture conditions caused the develoepment of complex small scale fermentation setups. The use of continuous fermentation and cell retention devices requires appropriate process control systems. An arrangement for control and data-acquisition of complex laboratory-scale bioreactors is presented. The fundamental idea was the usage of a standard personal computer, which is connected to pumps, valves and sensors via ADA-transformation. The possibility of free programming allowed the development of user-oriented software, especially designed for the far-reaching requirements of a university laboratory in the field of animal cell culture. Control of aeration, pumps, data-acquisition and data-storage are combined within one program, which allows the automation of standard operations like measurement of kLa- or OTR-values. Pump control algorithms for all common fermentation strategies (batch, fed batch, chemostat, perfusion) are included and can be selected any time during cultivation. Oxygen partial pressure and pH are controlled via direct digital control (ddc), providing simple adaption of control parameters and set points to current fermentation conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00762402
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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