Cellular dielectric spectroscopy

FIGURE 4.1 Assays commonly used in GPCR research. SPA = scintillation proximity assay FP = fluorescence polarization TR-FRET = time-resolved fluorescence resonance energy transfer FCS = fluorescence correlation spectroscopy SeAP = secreted alkaline phosphate TF = transcription factor EFC = enzyme fragment complementation DMR = dynamic mass redistribution CDS = cellular dielectric spectroscopy. 

This laboratory long ago devised [120] the use of radio-frequency dielectric spectroscopy [121, 122] for the on-line and real-time estimation of microbial and other cellular biomass during laboratory and industrial fermentations. The principle of operation is that only intact cells (see [123] for what is meant in this context by the word viable ), and nothing else likely to be in a fermentor, have intact plasma membranes and that the measurement of the electrical properties of these membranes allows the direct estimation of cellular biomass (Fig. 4). 

The use of dielectric spectroscopy for the characterization of living cells and the possible derivation of cellular parameters such as living ceU volume concentration (Figure 4.14), complex permittivity of extracellular and intracellular media, and morphological factors is discussed by Gheorghiu (1996). Another possible application is the electrical measurement of erythrocyte deformability (Amoussou-Guenou et al., 1995). 

Hillenbrand J, Sessler GM (2004) Quasistatic and dynamic piezoelectric coefficients of polymer foams and polymer film systems. Dielectr Electr Insul IEEE Trans 11 72-79 Kremer F, Schonhals A (2002) Broadband dielectric spectroscopy. Springer, Berlin Kressmann R (2001a) Linear and nonlinear piezoelectric response of charged cellular polypropylene. J Appl Phys 90 3489-3496... 

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