The Multi-Conductivity Clausius-Mossotti Factor as an Electrophysiology Rosetta Stone: Dielectrophoresis, Membrane Potential and Zeta Potential

Indeed, there are many aspects of the model presented here that raise questions about the nature of Vm. Vm as described by Equation (6) is of a system out of equilibrium, where ion channels are used to constantly pump ions against their concentration gradients to maintain the diffusion gradient giving rise to Vm. However, the fact that σcyto, which depends on the cytoplasm in concentration, varies linearly with σmed suggests that the process might be more of an equilibrium. One model that describes this is the Gibbs–Donnan model of permeant and non-permeant ions [36]; this is often dismissed for higher values of Vm as the required cytoplasm ion concentration would drive so much water ingress due to osmosis that the cell would burst. However, the model presented here suggests that this excess charge might only be present in the electrical double layer, and that it is this value that we actually observe when we extract the σcyto parameter using CM Modeling. This would change our understanding of the origin of Vm, at least for non-excitable cells; an issue with these models is that all were developed for excitable cells (muscle, nerve) between the 1930s and 1950s [39,40,41,42,43] and subsequently applied to all cells. These results suggest that this might not be the best approach. The work also highlights the importance of capacitance in the formation of Vm and may point towards new models of cell electrical behavior—and an expanding of our understanding of the role of the cellular electrome in wider cell biology

The Clausius–Mossotti spectrum has been used for the determination of cellular electrical properties for three decades. The ability it confers to allow dielectrophoresis to determine passive electrical properties of cytoplasm and membrane have allowed DEP to become a functional tool for cell electrophysiology. However, the parameters yielded by this method have found little traction with classical electrophysiology. Recent work has demonstrated that these parameters—and importantly, the way in which they change in media of different conductivity—allow the unlocking of further parameters that form a “Rosetta stone” between DEP, surface science, and conventional electrophysiology, and potentially unlocks new understandings of the role the cellular electrome plays in the function of the cell.