Photoinduced electron transport across phospholipid wall of liposome using methylene blue

Abstract

PHOTOSENSITISED electron transport across membranes is a useful model reaction for photosynthesis. We have previously reported¹ the photoredox reaction in/on liposomes. Other similar studies have used chlorophyll as a sensitiser^2,3, but this compound is easily broken and difficult to purify. The surfactant analogues of metal complexes (particularly tris-(2,2′-bipyridine) Ru²⁺)^4–6 are also widely used, but with such photosensitisers which possess long alkyl chains, electron transport does not occur in the absence of electron carriers such as quinones or carotenes. We report here the occurrence of photosensitised electron transport across the single phospholipid wall of the liposome using methylene blue as both a sensitiser and an electron carrier. This is the first report of photosensitised electron transport across a membrane using a dye not only as a photosensitiser but also as an electron carrier.