pH-Sensitive, cation-selective channels formed by a simple synthetic polyelectrolyte in artificial bilayer membranes

A synthetic amphiphilic polymer, poly(2-ethylacrylic acid), induces pore formation in artificial phospholipid bilayers under mildly acidic conditions. This process is pH-controllable and produces cation-selective ion channels of at least three unique large conductances with differing Na+/Cl- permeability ratio values. Two general types of channel gating kinetics are observed, one flickering and irregular and one regular and discrete. The discrete channel activity resembles that of well-characterized biological and synthetic peptides. Given the heterogeneity of polymer structure and conformation, this observation raises questions about the mechanism of polymer channel formation and the nature of these channels in lipid bilayer membranes.