Scaling Behavior of Ionic Transport in Membrane Nanochannels
We make use of scaling arguments to provide a common framework for two contrasting types of membrane biochannels, the narrow ones key to signaling and neurotransmission and the wide ones involved in keeping cell homeostasis through solute interchange. We show that when the characteristic size of the channel decreases to the nanoscale, surface and confinement effects become dominant
Queralt-Martin M, Lopez ML, Aguilella-Arzo M, Aguilella VM, Alcaraz A.
Nano Lett 2018 Oct; 18: 6604.
Ionic conductance in membrane channels exhibits a power-law dependence on electrolyte concentration ( G approximately c(alpha)). The many scaling exponents, alpha, reported in the literature usually require detailed interpretations concerning each particular system under study. Here, we critically evaluate the predictive power of scaling exponents by analyzing conductance measurements in four biological channels with contrasting architectures. We show that scaling behavior depends on several interconnected effects whose contributions change with concentration so that the use of oversimplified models missing critical factors could be misleading. In fact, the presence of interfacial effects could give rise to an apparent universal scaling that hides the channel distinctive features. We complement our study with 3D structure-based Poisson-Nernst-Planck (PNP) calculations, giving results in line with experiments and validating scaling arguments. Our findings not only provide a unified framework for the study of ion transport in confined geometries but also highlight that scaling arguments are powerful and simple tools with which to offer a comprehensive perspective of complex systems, especially those in which the actual structure is unknown.
PubMed: 30178677. Doi: 10.1021/acs.nanolett.8b03235.
