Cytotechnology

, Volume 55, Issue 2, pp 115–124

On-line monitoring of infected Sf-9 insect cell cultures by scanning permittivity measurements and comparison with off-line biovolume measurements

Special Issue JAACT

DOI: 10.1007/s10616-007-9093-0

Cite this article as:
Ansorge, S., Esteban, G. & Schmid, G. Cytotechnology (2007) 55: 115. doi:10.1007/s10616-007-9093-0

Abstract

Two infected Sf-9 cell cultures were monitored on-line by multi-frequency permittivity measurements using the Fogale BIOMASS SYSTEM® and by applying different off-line methods (CASY®1, Vi-CELL™, packed cell volume) to measure the biovolume and the mean diameter of the cell population. During the growth phase and the early infection phase the measured permittivity at the working frequency correlated well with the different off-line methods for the biovolume. We found a value of 0.67 pF cm−1 permittivity per unit of total biovolume (CASY) (μL mL−1). After the maximum value in the permittivity was reached, i.e. when the viability of the cultures decreased significantly, we observed different time courses for the biovolume depending on the applied method. The differences were compared and could be explained by the underlying measurement principles. Furthermore, the characteristic frequency (fC) was calculated from the on-line scanning permittivity measurements. The fC may provide an indication of changes in cell diameter and membrane properties especially after infection and could also be an indicator for the onset of the virus production phase. The changes in fC were qualitatively explained by the underlying equation that is correlating fC and the properties of the cell population (cell diameter, intracellular conductivity and capacitance per membrane area).

Keywords

Baculovirus Biomass Biovolume Capacitance Characteristic frequency Insect cell culture On-line monitoring Permittivity Scanning spectroscopy Sf-9 

Abbreviations

α

Cole–Cole alpha

CM

Capacitance per membrane area (F m−2)

Δε

Cell permittivity (pF cm−1)

ΔεFOGALE

Permittivity difference at f1 and f2 (pF cm−1)

fC

Characteristic frequency (Hz)

hema

Hemacytometer

KLa

Volumetric oxygen mass transfer coefficient (h−1)

PBS

Phosphate buffered saline

PCV

Packed cell volume (μL mL−1)

TOI

Time of infection with baculovirus (h)

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  1. 1.Pharmaceuticals DivisionF. Hoffmann-La Roche AG, Pharma Research Basel, Protein SciencesBaselSwitzerland
  2. 2.Animal Cell Technology GroupBiotechnology Research Institute, National Research Council CanadaMontrealCanada
  3. 3.FOGALE NanotechNimesFrance