Short talk:
Rational design of biophotoelectrodes for in vitro biocatalysis

Anna Frank1, Panpan Wang2, Felipe Conzuelo2,3, Wolfgang Schuhmann2, Marc Nowaczyk1

1Ruhr-Universität Bochum, Molecular Mechanisms of Photosynthesis, Bochum, Germany,
2Ruhr- Universität Bochum, Analytical Chemistry and Center for Electrochemical Sciences (CES) , Bochum, Germany,
3ITQB NOVA, Bioelectrochemistry and Electrobiotechnology, Oeiras, Portugal

The use of photosynthetic protein complexes for the fabrication of solar energy conversion devices is a promising strategy due to their natural abundancy and high quantum efficiency. Particularly one of the main photosynthesis-driving enzymes, photosystem I (PSI), is a stable protein complex able to convert visible light into high-energy electrons – making it an attractive candidate for the fabrication of biohybrid devices. One of the challenges in such devices is to overcome short-circuiting processes between the light-generated electrons and the electrode. One approach is oriented immobilization of PSI complexes in so-called Langmuir monolayers by taking advantage of their amphiphilic character, thus enabling anisotropic electron flow. Residual charge recombination occurring at the gaps between PSI trimers could be successfully closed by additionally employing smaller PSI monomers, resulting in increased surface coverage and overall performance. To promote efficient wiring between PSI complexes and the electrode, rationally designed redox-active polymers can be used as an effective tool. They enhance electron transfer and film stability and furthermore enable deposition of additional enzymes such as oxidoreductases to the photoelectrode to make use of the high energy electrons generated by PSI, as could be shown for a hydrogenase, resulting in light-driven H2 production. Further optimization of PSI-based biohybrid devices can be achieved via the use of transparent, 3D-structured electrodes that enable a significantly increased protein loading density and via decorating PSI complexes with additional light-harvesting antennae, closing the “green gap” and thus increasing the system’s overall quantum efficiency.


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