J. Am. Chem. Soc. 1996, 118, 5791-5795
5791
Fast and Efficient Charge Transport across a Lipid Bilayer Is Electronically Mediated by C70 Fullerene Aggregates Shufang Niu and David Mauzerall* Contribution from The Rockefeller UniVersity, 1230 York AVenue, New York, New York 10021 ReceiVed January 23, 1996X
Abstract: Fullerene anions, made by photoreduction in a lipid bilayer, produce the largest trans-membrane steady state photocurrents yet observed, ∼6.0 µA/cm2. Since these photocurrents are not light saturated, their maximum value is considerably larger. Dithionite was used as electron donor for its ability to reduce photoexcited fullerenes at the donor interface on a time scale faster than 15 ns. Both photovoltage and photocurrent increase 15-fold on adding the acceptor ferricyanide trans to the donor. There are two components to the transit time of negative charge across the bilayer, 100 mV with the asymmetric system dithionite|C70|ferricyanide and breaks the membranes. Thus the voltage measurements are carried out on partially polarized systems. The (11) Hwang, K. C.; Mauzerall, D. J. Am. Chem. Soc. 1992, 114, 9705. (12) Hwang, K. C.; Mauzerall, D. Nature 1993, 361, 138. (13) Hwang, K. C.; Niu, S.; Mauzerall, D. ECS Fullerene Symp. Proc. 1994, 94-24, 845. (14) Woodle, M.; Zhang, J. W.; Mauzerall, D. Biophys. J. 1987, 52, 577.
© 1996 American Chemical Society
5792 J. Am. Chem. Soc., Vol. 118, No. 24, 1996
Niu and Mauzerall
Table 1. Photoelectric Properties of C70 in a DPPC Bilayer Membrane with Dithionite as Donor and Different Acceptorsa acceptor pulsed light Vmaxfast, mV t1/2,risefast, µs Vmaxslow, mV t1/2,riseslow, µs Imaxfast, mAb t1/2,decayfast, µsc Imaxslow, µA t1/2,decayslow, µs continuous light Idark, nA Ilight, nA
-
AQS1-
Fe(CN)63-
MV2+
1.7 0.015 1.1 30
3.2 0.015 2.1 30
19.0 0.015 13.3 30
3.7 0.015 2.6 30
30 0.1
