On the mechanism of ubiquinone mediated photocurrent generation by a reaction center based photocathode

Friebe, Vincent M.; Swainsbury, David J. K.; Fyfe, Paul K.; Heijden, Wessel van der; Jones, Michael R.; Frese, Raoul N.

doi:10.1016/j.bbabio.2016.09.011

Cited by 31 publications

(44 citation statements)

References 65 publications

(143 reference statements)

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“…22 Upon photoexcitation with a 46 mW cm –2 870 nm LED, charge separation in the RC resulted in photo-oxidation of the primary electron donor (P + ), which was reduced by transfer of an electron from a bound cyt c . 32 Reduction of cyt c by the electrode resulted in a peak cathodic photocurrent of ∼100 μA cm –2 (Figure 1b), which translates to an apparent rate of RC turnover of 19 ± 5 e – s –1 (Table 1) or one electron every 53 ms.…”

Section: Resultsmentioning

confidence: 99%

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

Friebe¹,

Millo²,

Swainsbury

et al. 2017

ACS Appl. Mater. Interfaces

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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.

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Section: Resultsmentioning

confidence: 99%

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

Friebe¹,

Millo²,

Swainsbury

et al. 2017

ACS Appl. Mater. Interfaces

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“…[29][30][31][32][33][34][35][36][37] A wide variety of mediators for charge transport have also been explored with Q0, a water-soluble analogue of natural ubiquinone-10, being particularly effective. 38 The purpose of the present study was to examine whether synthetic conducting substrates that are often employed as transparent electrode materials in such devices, particularly of a two-electrode architecture, can be replaced by a biologically-derived alternative. We find that this was indeed the case, bio-photoelectrochemical cells employing ethyl-cellulose as a substrate for ITO and Au electrodes producing photocurrents and photovoltages that were similar to those from equivalent cells using ITO-PET as the substrate for the conductive coating.…”

Section: Resultsmentioning

confidence: 99%

Biodegradable Protein-Based Photoelectrochemical Cells with Biopolymer Composite Electrodes That Enable Recovery of Valuable Metals

Suresh

Vaghasiya

Jones

et al. 2019

ACS Sustainable Chem. Eng.

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The development of new technologies that use sunlight as an energy source is adding to pressure on finite natural resources and the challenges of recycling and disposal. Looking to nature for material assistance, we describe a proof-of-concept flexible and biodegradable photoelectrochemical cell based almost entirely on pigments, proteins, polysaccharides and graphene platelets. In addition to being largely environmentally benign, such devices present opportunities for the recovery of valuable components such as, in the present case, the geologically-scarce metal indium and the precious metal gold. Recovery is achieved through dissolution in ethanol followed by physical separation of the heavy element, leaving a residue made up from common elements that can be recycled through natural biodegradation. Potential applications for flexible, biomolecule-based photoelectrochemical cells are considered.

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“…Numerous studies have investigated the binding of photoactive proteins in various orientations, such as the P-side or Q-side to a bare electrode or surface-modified electrodes using self-assembled linkers. [11][12][13][14][15][16][17][18][19][20][21][22][23] Upon illumination and resultant charge separation, electrons are transferred to the protein from the electrode or from the protein to the electrode depending on the orientation of the protein. Photocurrent generation is, therefore, a function of the number of functional and properly-oriented proteins on the electrode surface, and signals obtained from biohybrid solar cells are typically on the order of nanoamps to microamps per cm 2 .…”

Section: Introductionmentioning

confidence: 99%

Highly Sensitive Method to Isolate Photocurrent Signals from Large Background Redox Currents on Protein‐Modified Electrodes

2019

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The high quantum efficiency in converting light energy into a charge-separated state is a major advantage in using photosynthetic proteins in biophotovoltaic applications. Photocurrents are typically measured at open circuit potential (OCP), where the electrochemical redox or faradaic currents are minimized. However, at potentials far from the OCP, the photocurrents produced by the proteins may be impossible to measure against the large background current, owing to electrochemical redox reactions of charge-transfer mediators and/or sacrificial electron donors. Demonstrated here is a highly sensitive method using a sinusoidal-modulated intensity of an LED excitation light source to isolate the protein-based photocurrent component from the total current irrespective of electrode surface coverage. Using a genetically modified photochemical reaction center from Rhodobacter sphaeroides as a proof-of-concept, photocurrents up to 10 4 -10 5 orders of magnitude smaller than the background electrochemical redox current (due to redox reactions directly on the electrode surface) were measured at applied voltages > 0.4 V from the OCP. The phase relationship between the optical excitation and photocurrent response was also measured and shown to be analytically useful.[a] Dr.

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On the mechanism of ubiquinone mediated photocurrent generation by a reaction center based photocathode

Cited by 31 publications

References 65 publications

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

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

Biodegradable Protein-Based Photoelectrochemical Cells with Biopolymer Composite Electrodes That Enable Recovery of Valuable Metals

Highly Sensitive Method to Isolate Photocurrent Signals from Large Background Redox Currents on Protein‐Modified Electrodes

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