Photoinduced electron transfer across a gold supported octadecanethiol/phosphatidylcholine hybrid bilayer membrane mediated by C₆₀ in different redox species solution

Electron transfer across the biomembrane is central to photosynthesis, to mitochondrial respiration and to the design of molecular systems for solar energy conversion. We report here that gold supported octadecanethiol/phosphatidylcholine hybrid bilayer membrane mediated by C₆₀ (abbreviated C₆₀ HBM) can act as both a photosensitizer for electron transfer from a donor molecule and a mediator for electron transport across a hybrid bilayer membrane. The steady-state photocurrent behaviors in different concentration of ascorbate, Co(bpy)₃^2+/3+ or Fe(CN)₆^4-/3- solution have been studied. The rate-limiting step of the whole photoinduced electron transfer depends on the applied potential and the redox concentration in solution. The C₆₀ HBM electrode was fabricated for the first time and there is no investigation on C₆₀ incorporated octadecanethiol/phosphatidylcholine hybrid bilayer membrane in literature. The sigmoidal-shaped steady-state photocurrent versus the applied potential curve is first observed and it is different from the linear-shaped i_ph/E curve of C₆₀ modified bilayer lipid membrane reported by Bensasson et al. [R.V. Bensasson, J.-L. Garaud, S. Leach, G. Miquel, P. Seta, Chem. Phys. Lett. 210 (1993) 141].