Impact of Surface Charge Heterogeneity on Ion Selectivity in Soft Nanopores: A Computational Study

Abstract

This study explores the role of surface charge heterogeneity in influencing ion selectivity within soft nanopores, with particular focus on how the combination of heterogeneous surface charge distribution and the elasticity of nanopores impacts ion flow and selectivity. The investigation centers on understanding how these two factors—surface charge distribution and nanopore deformation—affect both microscopic interactions (specifically between ions and the pore surface) and macroscopic ion transport dynamics (which includes bulk flow and ion selectivity). A hybrid computational approach is employed, integrating molecular dynamics (MD) simulations with continuum models such as Navier-Stokes for fluid flow, Poisson-Boltzmann for electrostatic potential, and Nernst-Planck for ion transport. This methodology allows for the dynamic modeling of both surface charge density variations and the elastic properties of nanopores, simulating their real-world behavior under varying conditions. The results show that heterogeneous surface charge distributions cause substantial variations in ion concentration profiles and selectivity within the nanopores, and that these effects are further modified by the elastic deformation of the nanopores. Unlike rigid nanopores, where the surface charge is fixed, soft nanopores exhibit adaptive ion selectivity, responding dynamically to the changing environmental conditions. These findings offer valuable insights for the design of smart nanofilters, biosensors, and energy harvesting systems where dynamic ion selectivity is critical to performance