Reversible control of vesicle formation using electrochemical reaction

Vesicle formation in an aqueous mixture of a ferrocene-modified cationic surfactant (FTMA) and anionic sodium dodecylbenzenesulfonate (SDBS) was reversibly controlled by redox reactions of FTMA on the electrode surface. Differential optical microscopic observation, dynamic light scattering measurements and cyclic voltammogram measurements showed that vesicles spontaneously formed at a 7:3 mixture of FTMA and SDBS disintegrate into much smaller assemblies by the oxidation of FTMA and the following re-reduction of the oxidized solution resulted in the re-constitution of vesicles. Aqueous compounds like glucose entrapped in the vesicles were released to bulk solution with the redox switching. This formation and disintegration of vesicles induced by the redox reactions were found to be brought about by drastic increase in hydrophilicity of the FTMA/SDBS pseudo double-tailed surfactant by the oxidation (ionization) of a ferrocenyl moiety. (C) 2003 Elsevier B.V. All rights reserved.