Roles of electroneutrality breakdown, membrane thickness, and dielectric mismatch in PNP spatiotemporal ionic reorganization

Determine the roles of (i) breakdown of electroneutrality, (ii) finite lipid membrane thickness, and (iii) dielectric mismatch between the lipid membrane and the surrounding electrolyte solutions in the spatiotemporal reorganization of ions near membranes within the Poisson–Nernst–Planck framework.

Background

Classical cable theory treats intracellular and extracellular media as resistors and the lipid membrane as a capacitor, assuming electroneutrality and neglecting spatiotemporal ionic dynamics. Recognizing these limitations, recent studies have employed Poisson–Nernst–Planck (PNP) models but often in 1D or with continued reliance on equivalent-circuit ideas, thereby neglecting in-plane interfacial phenomena and detailed electrostatics.

Within this context, the paper explicitly notes that key aspects remain unresolved even in PNP-based approaches: namely, how electroneutrality breakdown, membrane finite thickness, and the large dielectric mismatch between the membrane and electrolyte solutions shape spatiotemporal ionic reorganization near biological membranes.