Impact of Surface Charge Directionality on Membrane Potential in Multi-ionic Systems

Abstract

[EN] The membrane potential (V-mem), defined as the electric potential difference across a membrane flanked by two different salt solutions, is central to electrochemical energy harvesting and conversion. Also, V-mem and the ionic concentrations that establish it are important to biophysical chemistry because they regulate crucial cell processes. We study experimentally and theoretically the salt dependence of V-mem in single conical nanopores for the case of multi-ionic systems of different ionic charge numbers. The major advances of this work are (i) to measure Vmem using a series of ions (Na+, K+, Ca2+, Cl-, and SO42-) that are of interest to both energy conversion and cell biochemistry, (ii) to describe the physicochemical effects resulting from the nanostructure asymmetry, (iii) to develop a theoretical model for multi-ionic systems, and (iv) to quantify the contributions of the liquid junction potentials established in the salt bridges to the total cell membrane potential.