Biomimetic Metal‐Sorbing Vesicles: Cd2+ Uptake by Phosphatidylcholine Vesicles Doped with Ionophore A23187

Publisher Website
Google Scholar
Abstract
Unilamellar phosphatidylcholine vesicles, harboring the ionophore, A23187, in the bilayer and the water‐soluble chelating agent, nitrilotriacetate, in the vesicle interior, rapidly sequester and concentrate Cd2+ from dilute aqueous solution. Metal‐sorbing vesicle permeabilities for cadmium ion at 5 ppm (42.8 μM) ranged from 8.09 × 10−7 to 1.27 × 10−4 cm/s for surface A23187 concentrations of 0.22–2.27 pmol/cm2 (which correspond to lipid: carrier molar ratios of 2000:1 to 200:1) and pH's from 5.5 to 8.5. The Cd2+ permeability shows linear variation with carrier concentration under the conditions studied. As pH is decreased, an increasing fraction of the A23187 becomes protonated, and the permeability exhibits a positive linear relationship with a function related to that for the fraction of unprotonated carrier. These noncovalently assembled, metal‐sorbing vesicles exhibit shelf lives of several months and remain stable throughout typical metal sorption studies.