Effect of shape on the dielectric properties of biological cell suspensions

Structural and spectroscopic studies of DMPC/cationic surfactant system

“…In any biological or membrane system one must consider complex interfacial polarization mechanism leading to the so-called multi-shell model of complex permittivity [9]. For this reason the complex dielectric spectrum strongly depends on the morphology of phospholipids [9] and the shape of existing forms [38]. In general, besides the water relaxation detected at frequencies above 1 GHz (not visible in frequency range of our measurements) and reorientation of dipolar head groups of DMPC (found at frequency of 3 Â 10 7 Hz, presented in Fig.…”

Quantifying the membrane potential during E. coli growth stages

“…The independent input parameters entering the formula are: the volume fraction p of the cell solution, the outer and inner average radius of the cell's membrane, R 1 and R 2 (d = R 1 − R 2 ; consideration of a strict ellipsoidal shape for the cells makes very little difference [20,21]), the complex dielectric function of the medium ε 0 ⁎ = ε 0 + σ 0 / jω, of the membrane ε 1 ⁎ = ε 1 + σ 1 / jω and of the inner cell region ε 2 ⁎ = ε 2 + σ 2 / jω; the diffusion constant D of surface charges accumulated around the membrane and the resting membrane potential ΔV.…”

Complex Dielectric Properties of Sulfate-Reducing Bacteria Suspensions

“…In this range, the ε of live D. vulgaris suspensions is as high as 10 6 , being 6-to 10-fold higher in the OD 0.37 suspensions relative to the OD 0.28 suspensions. The significant α-dispersion depends not only on the conductivities of the extracellular medium and cell cytoplasm, but also on the cell size, shape, and biomass concentration (Di Biasio and Cametti 2007;Schwan 1957;Yang et al 1999). Previous work shows that living E. coli cells in pure water have ε of 10 5 and increasing with cell 494 Zhang et al As the cell ages, the relative dielectric permittivity decreases and the conductivity decreases (color figure available online).…”