Trans-membrane Electron Transport and the Redox Reactions of Dyes in a Single Wall Liposome System

Abstract

Dye-sensitized electron transport through the phospholipid wall of a single wall liposome system was studied in the presence of several redox dyes. The experiments were carried out in the single wall liposome system that contained the electron acceptor (K₃[Fe(CN)₆]) only in the inner aqueous phase and the electron donnor (sodium ascorbate) only in the outer aqueous phase. The reduction of K₃[Fe(CN)₆] accompanied with the trans-membrane electron transport was observed even in the dark for the dye with higher redox potential than that of ascorbate. Though the redction of K₃[Fe(CN)₆] was not observed in the dark for the dye with lower redox potential than that of ascorbate, it was induced by light irradiation. The electron transport observed here was completely coupled with the redox cycle of the dye, and the dye was recycled in the course of the electron transport reaction. These electron transport experiments were carried out both in the irradiated and non-irradiated system without using any quinones or carotenes.