Multifrequency permittivity measurements enable on-line monitoring of changes in intracellular conductivity due to nutrient limitations during batch cultivations of CHO cells

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DOIResolve DOI: http://doi.org/10.1002/btpr.347
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TypeArticle
Journal titleBiotechnology Progress
Volume26
Issue1
Pages272283; # of pages: 12
Subjectpermittivity; on-line monitoring; CHO cell cultures; physiological state; metabolic shift
AbstractLab and pilot scale batch cultivations of a CHO K1/dhfr- host cell line were conducted to evaluate on-line multifrequency permittivity measurements as a process monitoring tool. The b-dispersion parameters such as the characteristic frequency (fC) and the permittivity increment (Demax) were calculated on-line from the permittivity spectra. The dual-frequency permittivity signal correlated well with the off-line measured biovolume and the viable cell density. A significant drop in permittivity was monitored at the transition from exponential growth to a phase with reduced growth rate. Although not reflected in off-line biovolume measurements, this decrease coincided with a drop in OUR and was probably caused by the depletion of glutamine and a metabolic shift occurring at the same time. Sudden changes in cell density, cell size, viability, capacitance per membrane area (CM), and effects caused by medium conductivity (rm) could be excluded as reasons for the decrease in permittivity. After analysis of the process data, a drop in fC as a result of a fall in intracellular conductivity (ri) was identified as responsible for the observed changes in the dual-frequency permittivity signal. It is hypothesized that the b-dispersion parameter fC is indicative of changes in nutrient availability that have an impact on intracellular conductivity ri. On-line permittivity measurements consequently not only reflect the biovolume but also the physiological state of mammalian cell cultures. These findings should pave the way for a better understanding of the intracellular state of cells and render permittivity measurements an important tool in process development and control. -¬ 2009 American Institute of Chemical Engineers
Publication date
LanguageEnglish
AffiliationNRC Biotechnology Research Institute; National Research Council Canada
Peer reviewedYes
NRC number52779
NPARC number16945690
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Record identifierce48d69b-5f22-495f-827f-61dd4b6bfab2
Record created2011-03-31
Record modified2016-05-09
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