Bioelectronic Circuit on a 3D Electrode Architecture: Enzymatic Catalysis Interconnected with Photosystem I Dmitri Ciornii,* ,† Marc Riedel, † Kai R. Stieger, † Sven C. Feifel, † Mahdi Hejazi, ‡ Heiko Lokstein, § Athina Zouni, ‡ and Fred Lisdat* ,† † Biosystems Technology, Institute of Applied Life Sciences, Technical University of Applied Sciences Wildau, Hochschulring 1, 15475 Wildau, Germany ‡ Biophysics of Photosynthesis, Institute for Biology, Humboldt-University of Berlin, Philippstrasse 13, Haus 18, 10115 Berlin, Germany § Department of Chemical Physics and Optics, Charles University, Ke Karlovu 3, 121 16 Prague, Czech Republic * S Supporting Information ABSTRACT: Artificial light-driven signal chains are particularly important for the development of systems converting light into a current, into chemicals or for light- induced sensing. Here, we report on the construction of an all-protein, light-triggered, catalytic circuit based on photosystem I, cytochrome c (cyt c) and human sulfite oxidase (hSOX). The defined assembly of all components using a modular design results in an artificial biohybrid electrode architecture, combining the photophysical features of PSI with the biocatalytic properties of hSOX for advanced light-controlled bioelectronics. The working principle is based on a competitive switch between electron supply from the electrode or by enzymatic substrate conversion. I ntegration of biomolecules into an electrical circuit in which electrons can be routed in a desirable way represents an interesting topic in biomolecular electronics. It opens new perspectives for practical applications, where desired reactions can be triggered on demand or supplied with the needed energy. Thus, the design of functional biohybrid architectures on the nanoscale has gained intense research interest over the last decades. 1-4 Such biohybrids are based on an efficient biomolecule-electrode contact. This can be achieved via free or bound redox compounds, shuttling electrons between the electrode and the biocatalytic entity 5,6 or by direct electron transfer. 7,8 Efficient wiring of several biocatalysts with the electrode and with each other, however, remains challenging. One possibility for communication between multiple enzymes has been exploited by using reaction intermediates and establishing enzyme cascades, enzyme competition or recycling schemes on electrodes. 9-11 Metabolic channeling can be considered as a further advancement in constructing multienzyme complexes in an artificial way with reduced diffusion pathways. 12,13 Another step in the development of multiprotein systems represents the establishment of direct electron exchange between immobilized proteins on electrode surfaces. 14-16 Here the capability of natural redox proteins to communicate even with non-native partners can be exploited for the design of artificial signal cascades. 17 The successful integration of light-sensitive proteins with biocatalysts is a research target for which only recently first examples have been demonstrated, where biological light- converting complexes such as photosystem I (PSI) have been incorporated in biohybrid systems. 18, 19 The photoactive complex PSI has also been successfully coupled with a hydrogenase via a dithiol-linker allowing a photocatalytically driven electron supply for the enzyme. 20 Following this idea, it has been recently shown that hydrogen production and photocurrent production are feasible by combining PSI with a hydrogenase via a redox polymer on an electrode. 21 In a different approach, the enzyme glucose oxidase has been coupled to an electrode-fixed PSI resulting in enhancement of the anodic photocurrent in the presence of glucose. 22 These developments may illustrate that the combination of biocatalytic conversions with photoactive entities is advantageous in connecting complex redox reactions, because light and electrode potential can be used to control the processes. Encouraged by previous studies on photoelectrodes, we have developed a modular self-driven photobiocatalytic architecture, in which the photoactive unit, PSI, produces a light-induced current, human sulfite oxidase (hSOX) acts as an electron supplier for PSI and cytochrome c (cyt c) works as a molecular wire between the biocompounds and also toward the electrode. In our system, the assembly of several biomolecules results in an efficient interprotein electron transfer allowing the establish- ment of well-defined electron pathways. For the incorporation of the multiprotein system, we have used 3D inverse opal ITO (IO-ITO) electrodes (Figure S1, SI) applying the previously reported template-based preparation procedure. 23 IO-ITO electrodes provide a high surface area, which in turn allows for harboring large amounts of biomolecules. In this system, protein binding has been ensured without the need for polymers or mediators, but solely by adsorption due to the hydrophilic surface of such IO-ITO structures. Here, a sequential incubation procedure starting with PSI and hSOX followed by cyt c has been used (see SI for Received: September 22, 2017 Published: November 1, 2017 Communication pubs.acs.org/JACS © 2017 American Chemical Society 16478 DOI: 10.1021/jacs.7b10161 J. Am. Chem. Soc. 2017, 139, 16478-16481 Cite This: J. Am. Chem. Soc. 2017, 139, 16478-16481 Downloaded via UNIV OF UTAH on September 24, 2018 at 19:52:45 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.