Cytochrome c Provides an Electron-Funneling Antenna for Efficient Photocurrent Generation in a Reaction Center Biophotocathode

Vincent M. Friebe, Diego Millo, David J. K. Swainsbury, Michael R. Jones, Raoul N. Frese

Research output: Contribution to JournalArticleAcademicpeer-review


The high quantum efficiency of photosynthetic reaction centers (RCs) makes them attractive for bioelectronic and biophotovoltaic applications. However, much of the native RC efficiency is lost in communication between surface-bound RCs and electrode materials. The state-of-the-art biophotoelectrodes utilizing cytochrome c (cyt c) as a biological wiring agent have at best approached 32% retained RC quantum efficiency. However, bottlenecks in cyt c-mediated electron transfer have not yet been fully elucidated. In this work, protein film voltammetry in conjunction with photoelectrochemistry is used to show that cyt c acts as an electron-funneling antennae that shuttle electrons from a functionalized rough silver electrode to surface-immobilized RCs. The arrangement of the two proteins on the electrode surface is characterized, revealing that RCs attached directly to the electrode via hydrophobic interactions and that a film of six cyt c per RC electrostatically bound to the electrode. We show that the additional electrical connectivity within a film of cyt c improves the high turnover demands of surface-bound RCs. This results in larger photocurrent onset potentials, positively shifted half-wave reduction potentials, and higher photocurrent densities reaching 100 μA cm–2. These findings are fundamental for the optimization of bioelectronics that utilize the ubiquitous cyt c redox proteins as biological wires to exploit electrode-bound enzymes.
Original languageEnglish
Pages (from-to)23379-23388
Number of pages10
JournalACS Applied Materials and Interfaces
Issue number28
Publication statusPublished - 19 Jul 2017


M.R.J. and D.J.K.S. acknowledge support from the Biotechnology and Biological Sciences Research Council of the U.K. (project BB/I022570/1). R.N.F. acknowledges support from the Dutch Science Foundation NWO for a vidi grant, and D.M. for a veni grant (no. 722.011.003). Molecular graphics were performed with the UCSF Chimera package. Chimera is developed by the Resource for Biocomputing, Visualization, and Informatics at the University of California, San Francisco (supported by NIGMS P41-GM103311).

FundersFunder number
Dutch science foundation NWO722.011.003
National Institute of General Medical Sciences5P41GM103311-36
Biotechnology and Biological Sciences Research CouncilBB/I022570/1


    • biophotoelectrochemistry
    • biophotovoltaics
    • biosolar cells
    • cytochrome c
    • reaction center


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