Photocurrent Generation by Photosynthetic Purple Bacterial Reaction Centers Interfaced with a Porous Antimony-Doped Tin Oxide (ATO) Electrode

Abstract

The ability to exchange energy and information between biological and electronic materials is critical in the development of hybrid electronic systems in biomedicine, environmental sensing, and energy applications. While sensor technology has been extensively developed to collect detailed molecular information, less work has been done on systems that can specifically modulate the chemistry of the environment with temporal and spatial control. The bacterial photosynthetic reaction center represents an ideal photonic component of such a system in that it is capable of modifying local chemistry via light-driven redox reactions with quantitative control over reaction rates and has inherent spectroscopic probes for monitoring function. Here a well-characterized model system is presented, consisting of a transparent, porous electrode (antimony-doped tin oxide) which is electrochemically coupled to the reaction center via a cytochrome c molecule. Upon illumination, the reaction center performs the 2-step, 2-electron reduction of a ubiquinone derivative which exchanges with oxidized quinone in solution. Electrons from the electrode then move through the cytochrome to reoxidize the reaction center electron donor. The result is a facile platform for performing redox chemistry that can be optically and electronically controlled in time and space.

Enhancing Photocurrent Generation in Photosynthetic Reaction Center‐Based Photoelectrochemical Cells with Biomimetic DNA Antenna

“…Macroporous ATO coatings were prepared on fluorine‐doped tin oxide (FTO) glass as described previously and covered a 1 cm 2 area. Cytochrome c (equine heart, Sigma) was adsorbed to ATO films by incubating slides in a 50 μ m solution of cytochrome c in 5 m m phosphate buffer (pH 7.0) for 45 minutes.…”

“…Following the general processes in our previous work,, the RC–YDNA conjugates were then incorporated into macroporous antimony‐doped tin oxide (ATO) films, which had been impregnated with cytochrome c , on fluorine tin oxide (FTO) glass slides. The RCs were interfaced with the ATO pore surface via a cytochrome c bridge, which served as a redox wire . Dutta et al.…”

“…RC–DNA conjugates were prepared as reported by Dutta et al . Solutions of RCs and RC–DNA conjugates (in 15 m m Tris buffer with 0.05 % auryldimethylamine oxide (LDAO), 150 m m NaCl, 1 m m ethylenediaminetetraacetic acid (EDTA), and 6 m m Mg 2+ ) were incubated overnight under darkness at 4 °C with a tenfold molar excess of ubiquinone‐0 to replace the native ubiquinone in the QB binding pocket and then applied to ATO cytochrome c slides (15 μL of 7 μ m RC) and left to incubate overnight under darkness at 4 °C. Photoelectrochemical measurements were performed as described previously [3a] with the following alterations: ATO slides were illuminated by using a broad spectrum 20 W fiberoptic white lamp.…”

Thickness-Dependent Bioelectrochemical and Energy Applications of Thickness-Controlled Meso-Macroporous Antimony-Doped Tin Oxide

“…Finding the right conducting substrate for safely hosting biomacromolecules is necessary to transfer chemical potential from biochemical pathways to electrical circuits. Such porous electrodes open the way for hybrid photovoltaic [1][2][3][4][5][6][7][8][9], battery [10], photocatalytic [11][12][13][14] and sensing [15,16] applications. The high surface area provided by mesopores allows for high surface coverage of redox-active species on an electrode [7,[17][18][19][20], while the co-presence of openly connected macropores facilitates the better diffusivity of solvent and solutes for better electrochemical performance [9,[21][22][23] and is crucial for diffusion of bulky molecules through the entire coating thickness [15,16,24].…”

“…Macroporous coatings of transparent conducting oxides (TCOs), namely of SnO 2 and TiO 2 -based materials, have been synthesized by various methods. Aside from our previous reports [1,25], without employing pre-formed particles, meso-macroporous coatings have been fabricated with thickness up to 1 µm [11,26] which can accommodate one or two layers of macropores. However, by forming particles prior to depositing the meso-macroporous coatings, TiO 2 coatings with 15-20 µm thickness have been reported [6,7,27].…”