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Factors governing the photoelectrochemical output of photosynthetic microorganisms are poorly understood, and energy loss may occur due to inefficient electron transfer (ET) processes. Here, we systematically compare the photoelectrochemistry of photosystem II (PSII) protein-films to cyanobacteria biofilms to derive: (i) the losses in light-to-charge conversion efficiencies, (ii) gains in photocatalytic longevity, and (iii) insights into the ET mechanism at the biofilm interface. This study was enabled by the use of hierarchically structured electrodes, which could be tailored for high/stable loadings of PSII core complexes and Synechocystis sp. PCC 6803 cells. The mediated photocurrent densities generated by the biofilm were 2 orders of magnitude lower than those of the protein-film. This was partly attributed to a lower photocatalyst loading as the rate of mediated electron extraction from PSII in vitro is only double that of PSII in vivo. On the other hand, the biofilm exhibited much greater longevity (>5 days) than the protein-film (<6 h), with turnover numbers surpassing those of the protein-film after 2 days. The mechanism of biofilm electrogenesis is suggested to involve an intracellular redox mediator, which is released during light irradiation.
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http://dx.doi.org/10.1021/jacs.7b08563 | DOI Listing |
Adv Mater
August 2025
School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia.
Photosystem II (PSII) is a vital photosynthetic enzyme with the potential for sustainable bioelectricity and fuel generation. However, interfacing PSII with intricate, small-scale electrodes for practical applications has been challenging. This study addresses this by creating protonated macroporous carbon nitride (MCN) as support and developing a scalable spray-freeze method to wire PSII with MCN.
View Article and Find Full Text PDFAnal Chem
November 2024
Shenzhen Key Laboratory of Precision Measurement and Early Warning Technology for Urban Environmental Health Risks, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Despite its excellent efficiency in natural photosynthesis, the utilization of photosystem II (PSII)-based artificial photoelectrochemical (PEC) systems for analytical purposes is hindered due to the low enzyme loading density and ineffective electron transfer (ET) processes. Here, we present a straightforward and effective approach to prepare a PSII-based biohybrid photoanode with remarkable photoresponse, enabled by the use of a hierarchically structured inverse-opal tin oxide (IO-SnO) electrode combined with gold nanoparticles (Au NPs). The porous, carbon-containing IO-SnO structure allows for a high density and photoactivity loading of PSII complexes, while also providing strong electrical coupling between the protein film and the electrode.
View Article and Find Full Text PDFBioelectrochemistry
October 2023
Biosystems Technology, Institute of Life Sciences and Biomedical Technologies, Technical University of Applied Sciences Wildau, 15745 Wildau, Germany. Electronic address:
In this study, photobioelectrodes based on a ferredoxin-modified photosystem I (PSI-Fd) from Thermosynechococcus vestitus have been prepared and characterized regarding the direct electron transfer between PSI-Fd and the electrode. The modified PSI with the covalently linked ferredoxin (Fd) on its stromal side has been immobilized on indium-tin-oxide (ITO) electrodes with a 3-dimensional inverse-opal structure. Compared to native PSI, a lower photocurrent and a lower onset potential of the cathodic photocurrent have been observed.
View Article and Find Full Text PDFChemistry
February 2022
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599, United States.
In fabricating an artificial photosynthesis (AP) electrode for water oxidation, we have devised a semiconductor-mediator-catalyst structure that mimics photosystem II (PSII). It is based on a surface layer of vertically grown nanorods of Fe O on fluorine doped tin oxide (FTO) electrodes with a carbazole mediator base and a Ru(II) carbene complex on a nanolayer of TiO as a water oxidation co-catalyst. The resulting hybrid assembly, FTO|Fe O |-carbazole|TiO |-Ru(carbene), demonstrates an enhanced photoelectrochemical (PEC) water oxidation performance compared to an electrode without the added carbaozle base with an increase in photocurrent density of 2.
View Article and Find Full Text PDFAnal Chem
November 2021
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
The photoanode, photosystem II (PSII)/hierarchical inverse opal (IO) TiO, is coupled to the complementary photocathode, PbS quantum dots (QDs)/DNA probes, which is then integrated into a two-compartment photoelectrochemical (PEC) cell to achieve a self-powered system to enable photocathodic detection of microRNA-10b from HeLa cells. In such a system, all of the PSII catalytic products, i.e.
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