The dielectric behaviour of single-shell spherical cells with a dielectric anisotropy in the shell

Recent experiments on cells treated with hydrophobic ions showed that the mobile charges adsorbed to the plasma membrane contributed significantly to the low-frequency dielectric behaviour of cells. Due to the different transport properties of the mobile ions along the radial and tangential directions within the membrane, there is a dielectric anisotropy in the plasma membrane. In this work, we adopted a single-shell spherical cell model with an intrinsic dispersion in the membrane, which can be isotropic or anisotropic. We developed a dielectric dispersion spectral representation (DDSR) and expressed the Clausius-Mossotti factor in terms of a series of sub-dispersions. This representation enables us to assess the effects of the permittivities and conductivities in cells. We further assessed the effects of a dielectric anisotropy on the dispersion spectrum in the DDSR. To this end, we interpreted the results as a change in the dispersion strength, as well as a shift of the characteristic frequency. Moreover, the changes are indeed small and the weak-anisotropy expansion is justified.