Biomimetic metal-sorbing vesicles: Cd2+ uptake by phosphatidylcholine vesicles doped with ionophore A23187.
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 microM) ranged from 8.09 x 10(-7) to 1.27 x 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.
Chemical Engineering Department, University of California, Los Angeles 90024-1592.
J H
JH
van Zanten
H G
HG
Monbouquette
D000327:Adsorption; D001709:Biotechnology; D002104:Cadmium / Q000302:isolation & purification*; D000001:Calcimycin; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D008670:Metals / Q000302:isolation & purification; D008823:Micelles; D010539:Permeability; D010713:Phosphatidylcholines
D008670:Metals; D008823:Micelles; D010713:Phosphatidylcholines; D002104:Cadmium; D000001:Calcimycin