Reduced Graphene Oxide Combined with Photosystem I in Three-Dimensional Photobioelectrodes

Abstract

Photobioelectrodes or biophotovoltaics represent a rather new field of semiartificial systems within the field of bioenergy [1]. Here synthetic electrode materials are incubated with photoactive protein complexes, components, or whole cells to convert light into current and valuable chemicals. These bio-hybrid setups benefit from recent developments in materials chemistry. Thus, the characteristics can be tuned over a broad range to adapt the surface to the specific needs of the biomolecules.The aim of the work described here [2] is the facile construction of a scalable 3D photobioelectrode by incubation of graphene with photosystem I (PSI). Thereto reduced graphene oxide (rGO) was used as quasi graphene-like material because it is comparatively cheap and available in larger amounts [3]. The 3D structure results from a spin coating process with latex beads as templates. An approach that was successful for biophotovoltaics made of other materials was adapted to graphene oxide [4]. Next, the latex beads were removed by acetone and hydrazine was used to reduce the graphene oxide. The electrode structure was analysed with cyclic voltammetry, UV/VIS spectro-scopy and scanning electron microscopy.A photobioelectrode is setup by incubation of the structure with PSI. The assembly of the protein complex is confirmed just as the direct electron transfer from the rGO surface to the reaction center of PSI. The small redox protein cytochrome c is used to boost the performance of the photobioelectrodes. Then mediated electron transfer helps to connect as much PSI as possible. The biophotovoltaic was characterized with different electrochemical methods e. g. cyclic voltammetry, chopped light voltammetry, and photo action spectroscopy.The manufacturing process enables an adjustment of the thickness of the electrode by varying the number of spin-coating steps. The structure remains semi-transparent even for multiple layers of rGO. Thus, scalability of the photobioelectrode is in principle possible.Literature:[1] Lee I, Lee JW, Greenbaum E. Biomolecular Electronics: Vectorial Arrays of Photosynthetic Reaction Centers. Phys. Rev. Lett. 1997;79(17):3294–7.[2] Morlock S, Subramanian SK, Zouni A, Lisdat F. Scalable Three-Dimensional Photobioelectrodes Made of Reduced Graphene Oxide Combined with Photosystem I. ACS applied materials & interfaces 2021;13(9):11237–46.[3] Phiri J, Gane P, Maloney TC. General overview of graphene: Production, properties and application in polymer composites. Materials Science and Engineering: B 2017;215:9–28.[4] Ciornii D, Kölsch A, Zouni A, Lisdat F. A precursor-approach in constructing 3D ITO electrodes for the improved performance of photosystem I-cyt c photobioelectrodes. Nanoscale 2019;11(34):15862–70.