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lab 4 AP sample 2 - Biology Junction
In nature, quinone plays a vital role in numerous electrochemical reactions for energy transduction and storage; such processes include respiration and photosynthesis. For example, fast proton-coupled electron transfer between primary and secondary quinones in green plants triggers the rapid charge separation of chlorophyll molecules, achieving unparalleled photosynthesis with near-unity quantum yield. In addition, quinone-rich polymers such as eumelanin and polydopamine show unique optical and electrical properties (e.g., strong broadband absorbance or a switching response to external stimuli), mostly arising from their chemically disordered structures. Understanding the unique features of quinone and its derivatives can provide solutions to the construction of bio-inspired systems for energy harvesting and conversion. This paper reviews recent advances in the design of quinone-functionalized hybrid materials based on quinones redox, electrical, optical, and metal chelating/reducing properties to determine these materials applications in energy-harvesting and -storage systems, such as artificial photosynthetic platforms, rechargeable batteries, pseudocapacitors, phototransistors, plasmonic light harvesting platforms, and dye-sensitized solar cells.
Solar energy utilization is accomplished in green plants through a cascade of photo-induced electron transfer, which remains a target model for realizing artificial photosynthesis. In this article, we introduce the concept of about how to design biocatalyzed artificial photosynthesis through coupling redox biocatalysis and photocatalysis to mimic natural photosynthesis. Key design principles for reaction components, such as electron donors, photosensitizers, and electron mediators, are described for artificial photosynthesis involving biocatalytic assemblies. Recent research outcomes that serve as a proof of the concept are summarized and current issues are discussed to provide a future perspective.
AP Biology | Alexis's Digital Portfolio
Artificial photosynthesis is an attractive way to utilize solar energy through inspiration from natural photosynthesis in green plants. Water-splitting is critically required to establish an artificial photosynthetic system that consists of sequential charge-obtaining and transferring reactions. The oxidation of water is a limiting step to achieving water-splitting because of its multi-hole-related characteristics. A key to the development of effective water oxidation catalysts is the optimized control of material structure and composition through a facile synthetic method. This work synthesized polycrystalline RuO2/Co3O4 core/shell nanofibers by electrospinning and evaluated their photocatalytic water oxidation performance using a Ru(bpy)32+/persulfate system under visible light illumination. Our results show that RuO2/Co3O4 nanofibers exhibit significantly enhanced efficiency of photocatalytic water oxidation with a higher number of turnover frequency than those of pristine Co3O4 nanoparticles, Co3O4 nanofibers, and RuO2 nanofibers, respectively. The unique core-shell structure of RuO2/Co3O4 nanofibers comprising the inner region of highly conductive RuO2 and the outer region of catalytic Co3O4 provided a fast and effective transport highway for holes to O2-evolving sites. This work highlights the potential of tailored 1D binary composite nanofibers for the development of efficient oxygen-evolving catalysts and offers a new viewpoint for exploring multi-component catalysts through electrospinning.
Cellulose, a main component of green plants, is the most abundant organic chemical on Earth, produced 1011 tons per year in the biosphere. The polysaccharide consists of D-glucose units linked by beta-1,4-glycosidic bonds and has been widely utilized in diverse engineering fields because of its biocompatibility, abundance, and high chemical stability. In this work, we have demonstrated the utility of carboxymethyl cellulose (CMC) fibers as a sacrificial template to produce binary and tertiary metal oxides fibers. The electrostatic interaction between metal ions and the carboxyl groups in CMC fibers induced a hierarchical structure of metal oxides. The morphologies of synthesized metal oxides (e.g., CeO2, ZnO, and CaMn2O4) could be controlled according to synthetic conditions, such as metal precursor concentration, calcination temperature, and the amount of CMC fibers. Thus-synthesized CMC-templated metal oxide fibers exhibited enhanced performances for photocatalytic, photochemical, and electrocatalytic reactions. The CeO2 fibers showed much higher photocatalytic activity than CeO2 nanoparticles due to superior ability to generate reactive oxygen species which can degrade organic pollutants. We also demonstrated that hierarchical ZnO fibers hybridized with g-C3N4 could provide directional charge transfer pathway and showed their utility for biocatalyzed artificial photosynthesis through visible light-driven chemical NADH regeneration coupled with redox enzymatic reaction. The electrochemical properties of CaMn2O4 fibers enabled bi-functional reactions of oxygen reduction and evolution reactions. We expect that the economical and environmentally friend approach could be extended to green synthesis of hierarchically structured materials of other metal oxides.
Independent Investigation: Rate of Photosynthesis Lab
In the past 50 years, cytochrome P450 monooxygenases (P450s) have been given significant attention for the synthesis of natural products (e.g., vitamins, steroids, lipids) and pharmaceuticals. Despite their potential, however, costly nicotinamide cofactors such as NAD(P)H are required as reducing equivalents; thus, in situ regeneration of NAD(P)H is essential to sustaining P450-catalyzed reactions. Furthermore, poor stability of P450s has been considered as a hurdle, hampering industrial implementations of P450-catalyzed reactions. Herein we describe the development of an economic and robust process of P450-catalyzed reactions by the combination of P450 immobilization and solar-induced NADPH regeneration. The P450 monooxygenase could be efficiently immobilized on a P(3HB) biopolymer, which enabled simple purification from the E. coli host. We clearly demonstrated that the P450-P(3HB) complex exhibited much higher enzymatic yield and stability than free P450 did against changes of pH, temperature, and concentrations of urea and ions. Using the robust P450-P(3HB) complex and solar-tracking module, we successfully conducted P450-catalyzed artificial photosynthesis under the irradiation of natural sunlight in a preparative scale (500 mL) for multiple days. To the best of our knowledge, this is the largest reactor volume in P450-catalyzed reactions reported so far. We believe that our robust platform using simple immobilization and abundant solar energy promises a significant breakthrough for the broad applications of cytochrome P450 monooxygenases.
Green conversion of carbon dioxide to fuels has attracted high interest recently due to the global issues of environmental sustainability and renewable energy sources. In this study, we present photoelectrochemical (PEC) regeneration of nicotinamide cofactors (NADH) coupled with enzymatic synthesis of formate from CO2 towads mimicking natural photosynthesis. The water oxidation-driven PEC platform exhibited high yield and rate of NADH regeneration compared to many other homogeneous, photochemical systems. We successfully coupled solar-assisted NADH reduction with enzymatic CO2 reduction to formate under continuous CO2 injection.
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Essay about Ap Photosynthesis Lab Conclusion - 674 …
In green plants, solar-powered electrons are transferred through sophistically arranged photosystems and are subsequently channelled into the Calvin cycle to generate chemical energy. Inspired by the natural photosynthetic scheme, we have constructed a photoelectrochemical cell (PEC) configured with protonated graphitic carbon nitride (p-g-C3N4) and carbon nanotube hybrid (CNT/p-g-C3N4) film cathode and FeOOH-deposited bismuth vanadate (FeOOH/BiVO4) photoanode for the production of industrially useful chiral alkanes using an old yellow enzyme homologue from Thermus scotoductus (TsOYE). In the biocatalytic PEC platform, photoexcited electrons provided by the FeOOH/BiVO4 photoanode are transferred to the robust and self-standing CNT/p-g-C3N4 hybrid film that electrocatalytically reduces flavin mononucleotide (FMN) mediator. The p-g-C3N4 promoted a two-electron reduction of FMN coupled with an accelerated electron transfer by the conductive CNT network. The reduced FMN subsequently delivered the electrons to TsOYE for the highly enantioselective conversion of ketoisophorone to (R)-levodione. Under light illumination (> 420 nm) and external bias, (R)-levodione was synthesized with the enantiomeric excess value of above 83%, not influenced by the scale of applied bias, simultaneously exhibiting stable and high current efficiency. Our results suggest that the biocatalytic PEC made up of economical materials can selectively synthesize high-value organic chemicals using water as an electron donor.
Honors Biology: Online Labs Quiz Flashcards | Quizlet
Natural photosynthesis is an effective route for clean and sustainable conversion of CO2 to high-energy chemicals. Inspired by the natural scheme, we designed a tandem-photoelectrochemical (PEC)-cell-integrated-with-enzyme-cascade (TPIEC) system, which transfers photogenerated electrons to a multi-enzyme cascade for biocatalyzed reduction of CO2 to methanol. We applied a hematite photoanode and a bismuth ferrite photocathode to fabricate the iron oxide-based tandem PEC cell for visible light-assisted regeneration of nicotinamide cofactor (NADH). The cell utilized water as an electron donor and spontaneously regenerated NADH. To complete the TPIEC system, a superior three-dehydrogenase cascade system was employed in the cathodic part of the PEC cell. Using applied bias, the TPIEC system achieved high methanol conversion output, providing a PEC platform for highly selective synthesis of hydrocarbon fuel using readily-available solar energy and water.
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