Structural Thermodynamics of Membrane Electroporation: Voltage-Driven Interdigitation Induces Electro-Topological...

Electroporation triggers topological transitions in lipid membranes, yet the nanoscale spatiotemporal reorganization of cholesterol (Chol), acyl chains, and local electrostatic fields remains unexplored. Employing molecular dynamics (MD) simulations coupled with enhanced sampling, we map the structural thermodynamics of pore nucleation across multiple lipid species and Chol concentrations, analyzing 99 membrane systems (33 zero- and 66 applied-field) totaling >0.40 ms of MD sampling. We reveal that pore-induced acyl-chain interdigitation acts as a thermodynamic barrier, forcibly expelling rigid Chol. Whole-membrane z-profiles of membrane potential and water-dipole orientation largely mirror bulk behavior, showing that global averaging masks the pore-core electrostatic response and necessitating characteristic-radius-resolved local sampling. Crucially, high applied potentials induce an electro-topological disparity: voltage-driven leaflet interpenetration structurally outpaces aqueous pore dilation. Radius-resolved electrostatic matrices, phenotype clustering, and state-progression analyses show that interdigitation-defined local domains concentrate core water ordering and potential amplification. Rather than a simple nanoscale hole, this extensive electro-deformation generates an expanded "lipid scar" characterized by substantial tail entanglement, sharp lateral sterol gradients, and localized electrostatic enrichment. This amplified structural prestrain creates a thermodynamically vulnerable domain, potentially lowering the activation energy for consecutive poration, clarifying the molecular origins of electrosensitization in pulsed electric field therapies.