Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：India

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

Poly-3-hydroxybutyrate (PHB)-derived plastics having good biodegradability are attractive materials to solve the issue of serious environmental pollution due to plastic disposal. The production of a new PHB precursor 3-hydroxybutyrate from CO2 and acetone using a visible-light-driven catalytic system consisting of an electron donor, a photocatalytic dye, an electron mediator, and biocatalysts is an environmental approach for both plastic pollution and global warming. In this work, the visible-light driven 3-hydroxybutyrate production from acetone and low-concentration CO2 captured from the gas phase by 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES)-NaOH buffer solution with the combination of a NAD+ reduction system of triethanolamine (TEOA), water-soluble zinc porphyrin, zinc meso-tetra(4-sulfonatophenyl)porphyrin tetrasodium salt (ZnTPPS) and the Rh coordination complex ([Cp*Rh(bpy)(H2O)]2+; Cp* = pentamethylcyclopentadienyl, bpy = 2,2′-bipyridyl), and an enzyme extract including acetone carboxylase (AC; EC 6.4.1.6) and 3-hydroxybutyrate dehydrogenase (HBDH; EC 1.1.1.30) obtained from a purple nonsulfur photosynthetic bacterium, Rhodobacter capsulatus SB1003 (Rb. capsulatus SB1003) cultured in a medium containing acetone and bicarbonate under anaerobic photoheterotrophic conditions was investigated. It was found that acetone can be converted into 3-hydroxybutyrate in high yield (more than 60%) by directly using 15% CO2 equivalent to exhaust gas as a carboxylating agent. Moreover, the development of the visible-light driven 3-hydroxybutyrate production from 15% CO2 and waste acetone as raw materials was also accomplished.

DOI： 10.1039/d3gc00247k

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Poly-3-hydroxybutyrate (PHB)-derived plastics are polymer materials with excellent biodegradability, being insoluble in water and relatively resistant to hydrolysis. There is a need for a method capable of synthesizing 3-hydroxybutyrate, a monomer of PHB, from a renewable material. In this work, visible-light driven 3-hydroxybutyrate from CO2 and acetone with the system consisting of triethanolamine, water-soluble zinc porphyrin, pentamethylcyclopentadienyl coordinated rhodium complex, NAD+ and a cell extract containing acetone carboxylase and 3-hydroxybutyrate dehydrogenase from Rhodobacter capsulatus SB1003 cultured in acetone-bicarbonate medium is established. In particular, the conversion yield for acetone to 3-hydroxybutyrate was improved up to 81% in this system after 7 h irradiation.

DOI： 10.1039/d2cc03660f

PubMed

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

The sulfo group bonded to the water-soluble zinc porphyrin had a strong inhibition to the catalytic activity of FUM for l-malate dehydration to fumarate.

DOI： 10.1039/d3nj02900j

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DOI： 10.1246/BCSJ.20230026

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

Carbon capture and utilization (CCU) technology is the process of capturing and converting CO2 into useful materials for further usage. The CCU aims to convert the captured CO2 into more valuable materials while maintaining the carbon neutrality of the production process. In this work, we have demonstrated the acetoacetate production from acetone and NaHCO3 using acetone carboxylase (AC) in cell extract from photosynthetic bacteria Rhodobacter capsulatus strain SB1003 (Rb. capsulatus SB1003) cultured in a medium containing acetone and bicarbonate under anaerobic photoheterotrophic conditions as a catalyst in the presence of ATP. Steady acetoacetate production due to the carboxylation of acetone with NaHCO3 was accomplished in the presence of ATP by using cell extract including AC from Rb. capsulatus SB1003. Moreover, steady acetoacetate production from acetone and gaseous CO2 also was attained by using cell extract.

DOI： 10.1007/s10563-022-09371-x

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

Visible-light driven redox catalytic systems are attracting extensive attention not only in the fields of water splitting and CO2 reduction, but also in the organic synthesis for sustainable chemicals such as engineering, biodegradable polymers and their raw materials. L-Lactate has long been attracting attention as a raw material for biodegradable polymers, poly (L-lactate). In this study, an enantioselective pyruvate reduction to L-lactate using a visible-light driven redox system consisting of water-soluble zinc porphyrin as a photosensitizer, rhodium complex [Rh(Cp*)(bpy)(H2O)]2+ (Cp* = pentamethylcyclopentadienyl, bpy = 2,2′-bipyridyl) as a hydride and an electron mediator, NAD+ and lactate dehydrogenase from pig heart (LDH, EC 1.1.1.27) as a catalyst as a new L-lactate production method without toxic substance such as hydrogen cyanide is developed. By using this visible-light redox system, the reduction efficiency of pyruvate to L-lactate was achieved up to 26.7% with visible light irradiation for 19 h.

DOI： 10.1016/j.cattod.2022.04.018

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1039/D2SU00031H

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1016/j.electacta.2023.142590

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

Fumaric acid is a very useful unsaturated dicarboxylic acid because it is a raw material for unsaturated polyester resin. Fumarate is mainly synthesized currently from petroleum resources, with a large amount of CO2 emitted during its production. Thus, it is desirable to develop fossil-fuel-independent fumarate production methods, in particular those using renewable resources. In this work, visible-light-driven production of fumarate from CO2 and pyruvate with a system consisting of triethanolamine, water-soluble zinc porphyrin, pentamethylcyclopentadienyl-coordinated rhodium complex, NAD+, malate dehydrogenase (NAD+-dependent oxaloacetate-decarboxylating) and fumarase was developed. Our work with this system was, to the best of our knowledge, the first example of achieving the fixation of CO2 to pyruvate using electron accumulation in NAD+ with light energy as well as the conversion of the resulting fixed pyruvate to an unsaturated dicarboxylate.

DOI： 10.1039/d2se01533a

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CO2 fixation, a key to solving global warming, can convert CO2 into various compounds, unlike CO2 reduction; however, it is thermodynamically challenging to fix CO2 to a simple organic molecule. This study has developed a new synthesis of β-hydroxybutyrate, a monomer of a biodegradable polymer, from CO2 and acetone using the effective biocatalysts acetone carboxylase (AC) and β-hydroxybutyrate dehydrogenase (HBDH). AC is an attractive biocatalyst that catalyzes the introduction of CO2 to acetone to form acetoacetate in the presence of the co-enzyme ATP. To make the produced unstable acetoacetate more profitable, HBDH was introduced to catalyze acetoacetate reduction to β-hydroxybutyrate in the presence of the co-enzyme NADH. Rhodobacter capsulatus SB1003, a purple nonsulfur photosynthetic bacterium, successfully expressed both AC and HBDH in the acetone-bicarbonate medium under photoheterotrophic conditions. One-pot β-hydroxybutyrate synthesis from CO2 and acetone combining AC for CO2 fixation to acetone and HBDH for acetoacetate reduction to β-hydroxybutyrate has thus been developed using a cell extract including AC and HBDH from Rb. capsulatus. The optimal reaction conditions for the one-pot β-hydroxybutyrate synthesis were found based on the enzymatic activities of AC and HBDH, and the reaction rate was successfully increased by up to three times.

DOI： 10.1039/d2se01150f

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1246/bcsj.20220228

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

Fumarate is a useful unsaturated dicarboxylic acid that is used as a raw material for unsaturated polyester resins and polyhydric alcohols and as a mordant for dyes. Fumaric acid is synthesized from petroleum-derived benzene or butane as a starting material, and it is desired to develop a method for preparing it from renewable raw materials. In this work, the biocatalytic synthesis of fumarate from CO2 and pyruvate vial-malate as an intermediate in an aqueous medium using a biocatalytic system consisting of malate dehydrogenase (oxaloacetate-decarboxylating; ME) and fumarase (FUM) in the presence of NADH is accomplished. The conversion yield for pyruvate to fumarate with the system of ME and FUM in the presence of NADH was estimated to be 14.4% after 25 h.

DOI： 10.1039/d2re00039c

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

Selective H2 production based on formate decomposition with colloidal platinum nanoparticles dispersed by polyvinylpyrrolidone (PVP) and a cationic polymer, poly(diallyldimethylammonium chloride) (PDADMA) (Pt-PVP/P), is demonstrated. By using Pt-PVP/PDADMA, a substantially higher rate of selective H2 production based on formate decomposition was accomplished compared with that by using Pt-PVP. Notably, the rate of H2 production from an acidic solution, the pH of which was lower than the pKa of formic acid, was drastically improved (8.5 times higher than that by Pt-PVP at pH 2.0). The activation energy for decomposing formate into H2 and CO2 was reduced by up to 38% compared to that by Pt-PVP.

DOI： 10.1039/d2se00865c

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

Formate dehydrogenase from Candida boidinii (CbFDH) reversibly catalyzes formate to CO2 with the redox couple NAD+/NADH. While many studies on CbFDH-catalyzed formate oxidation in the presence of NAD+ are reported, there are few studies on the detailed mechanism of the CbFDH-catalyzed CO2 reduction in the presence of NADH. In this study, the detailed mechanism of formate production by CbFDH with NADH in GTA buffer solution (consisting of 3,3-dimethylglutaric acid, tris(hydroxymethyl)aminomethane and 2-amino-2-methyl-1,3-propanediol) with different proportions of CO2, bicarbonate and carbonate was studied. A good correlation was found between the pH of the buffer solution, the CO2 concentration and the apparent initial rate of formate production with CbFDH. Under constant conditions of total carbonate concentration in the buffer solution, the process of the CbFDH-catalyzed reduction of CO2 to formate followed the Michaelis-Menten kinetics. Particularly, the reaction rate of formate production with CbFDH increased with increasing CO2 concentration under constant conditions of total carbonate concentration in the solution. As the apparent formate production rate with CbFDH increases under higher total carbonate concentration, bicarbonate or carbonate does not act as a competitive inhibitor of CO2, and it is predicted that the CO2 concentration equivalent consumed in the CbFDH-catalyzed formate production is supplied by bicarbonate or carbonate by the pH control function of the GTA buffer solution. Thus, we have clarified for the first time that these carbonates do not function as any inhibitor for the CbFDH-catalyzed CO2 reduction.

DOI： 10.1039/d2nj00575a

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

Methanol fuel is paid much attention as an alternative lower carbon fuel for internal combustion and other engines. In this work, the bioelectrocatalytic methanol production from formaldehyde with alcohol dehydrogenase from Saccharomyces cerevisiae (ADH) using methylviologen (MV2+) as an electron mediator was developed toward establishing a method for synthesizing CO2 to methanol. When a single-electron reduction potential of MV2+ (-700 mV vs. Ag/AgCl electrode as a reference) was applied in the presence of ADH, reduction of formaldehyde to methanol was observed. After 90 min continuous external bias of -700 mV, 22.6% formaldehyde consumption based on methanol production was observed in this bioelectric catalyst system.

DOI： 10.1039/d2ya00054g

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

Methanol production based on the electrochemical reduction of CO2 is one possible method for synthesizing electrofuels (e-fuels). A multi-electron system for reducing CO2 to methanol using multi-biocatalysts and an artificial cofactor has attracted significant attention. For example, using formate, formaldehyde and alcohol dehydrogenase, CO2 is electrochemically reduced to methanol via formate and formaldehyde intermediates, with the rapid reduction of formate to formaldehyde being a particularly important step. Here, we developed a system for the electrochemical production of formaldehyde from formate by formaldehyde dehydrogenase (FldDH; EC.1.2.1.46) using methylviologen (MV2+) as an artificial cofactor. Application of a single-electron reduction potential of MV2+ (−700 mV vs. Ag/AgCl electrode) to electrolyte containing formate and FldDH resulted in formaldehyde production, and this production improved as the pH of the electrolytic solution increased. The maximum conversion yield for formaldehyde production was 1.1%, achieved at pH 10.3 after 3 h continuous application of an external electrochemical bias. Thus, the electrochemical formaldehyde production efficiency catalyzed by FldDH with MV2+ as an electron mediator was determined for the first time. Furthermore, the interaction between the substrate binding site of FldDH and the cation radical of MV2+ was predicted by docking simulation, providing insights into the electrochemical formate reduction process. Since the reduction of formate catalyzed by FldDH to formaldehyde is a two-electron reduction process, two molecules of cation radical of MV2+ are required. There is insufficient space in the substrate binding pocket of FldDH for two molecules of the MV2+ radical cation and thus the re-reduction of MV2+ bound to FldDH is an important process. Our findings indicate that efficient electron injection from the electrode into MV2+ bound to FldDH is a key process in formate reduction, an important step towards the reduction of CO2 to methanol.

DOI： 10.1039/d2nj00692h

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

The photo and biocatalyst hybrid system is one of the most ideal artificial photosynthetic systems using solar energy to synthesize various chemicals and fuels. This study was devoted to achieving visible-light-driven molecular conversion with various enzymes using the NADH regeneration system consisting of an electron donor such as triethanol amine (TEOA), zinc tetraphenylporphyrin tetrasulfonate (ZnTPPS) as a photosensitizer and colloidal polyvinylpyrrolidone-dispersed rhodium nanoparticles (Rh-PVP) as a catalyst. The irradiation wavelength dependence of NADH regeneration with the system of TEOA, ZnTPPS, Rh-PVP and NAD+ was studied and the quantum efficiency for NADH regeneration at monochromatic 420 nm due to the Soret band of ZnTPPS was estimated to be ca. 0.0012%. This NADH regeneration system was also applied to various enzyme-catalyzed redox reactions. By using this NADH regeneration system in the presence of lactate or d-3-hydroxybutyrate dehydrogenases, various enantioselective molecular conversions by visible-light energy were accomplished. By using this NADH regeneration and malate dehydrogenase (decarboxylating), photo and biocatalytic CO2 fixation to organic molecules based on carbon-carbon bond formation between pyruvate and CO2 has been successfully achieved. The results not only show an example of colloidal metal nanoparticles used as a catalyst for selective NADH regeneration in general artificial photosynthesis but also the selective production of chemicals/solar fuels directly from CO2 with visible-light energy.

DOI： 10.1039/d2se00454b

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The effects of isotope-labelled NADH and CO2 on formate dehydrogenase from Candida boidinii (CbFDH)-catalyzed CO2 reduction activity were investigated. It was found that the rate of CO2 reduction to formate with CbFDH decreased by using deuterium-labelled NADH (NADH-d4) as a co-enzyme. In contrast, the rate of CbFDH-catalyzed CO2 reduction to formate was unchanged in the use of 13CO2 as a substrate. In the substrate 12CO2 and 13CO2 is mixed, however, curious phenomenon on CbFDH-catalyzed CO2 reduction activity decrease was observed.

DOI： 10.1246/bcsj.20220023

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

Three kinds of heteroleptic Cu(I) complexes having a phenanthroline-based ligand acting as a chromophore and bearing benzoxazole, benzothiazole, and thiazole moieties were synthesized. Introduction into the phenanthroline ligands of electron-withdrawing five-membered aryl groups caused large red-shifts in the metal-to-ligand charge transfer bands, showing visible light absorption up to 500 nm. The obtained Cu(I) complexes exhibited emissions with quantum yields of 0.01-0.04 and long lifetimes of 0.4-3 mu s.

DOI： 10.1246/cl.210583

Publishing type：Research paper (scientific journal)  

DOI： 10.1039/d1re00405k

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1039/d1se01399h

Publishing type：Research paper (scientific journal)  

DOI： 10.1039/d1nj02856a

Publishing type：Research paper (scientific journal)  

DOI： 10.1039/d1nj02481g

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

<p>A selective pyruvate reduction to lactate using a visible light-driven redox system consisting of water-soluble zinc porphyrin as a photosensitizer, methylviologen as an electron mediator and platinum nanoparticles dispersed on poly(vinylpyrrolidone) as a catalyst, is developed as a new lactate production method without toxic substances.</p>

DOI： 10.1039/d1nj02676c

Publishing type：Research paper (scientific journal)  

Formate is attracting attention as a hydrogen carrier because of its low toxicity and easy handling in aqueous solution. In order to utilize formic acid as a hydrogen carrier, a catalyst for efficiently and selectively decomposing formic acid into H-2 in a low pH region is required. In this work, enhancement of selective H-2 production from formate with platinum nanoparticles dispersed by polyvinylpyrrolidone (PVP) and cationic poly-l-amino acid, poly(l-lysine) (PLL), poly(l-histidine)(PLH) and poly(l-arginine)(PLR) (Pt-PVP/PLX; X = L, H or R) in a low pH region was attempted. By using all Pt-PVP/PLX or Pt-PVP for formate decomposition catalysts, the amount of H-2 produced was maximized using an aqueous formate solution with a pH of 3.5 (close to a pK(a) of 3.75 of formic acid). The H-2 production catalytic activity of Pt-PVP/PLX (X = L or H) improved compared with that of Pt-PVP in the low pH range (pH = 1.8). By using Pt-PVP/PLL, especially, the amount of H-2 produced was improved to about 1.8 times compared to that of Pt-PVP under a pH = 1.8 condition. There was no difference in the electronic states of the platinum nanoparticles in Pt-PVP and Pt-PVP/PLL according to the extended X-ray absorption fine structure and X-ray absorption near edge structure spectra measurements. The amount of H-2 produced tended to increase as the PLL content ratio in Pt-PVP/PLL increased and the protonated alkylammonium moiety of PLL in Pt-PVP/PLL attracted the dilute formate ions in the solution to platinum nanoparticles, and the catalytic activity for H-2 production was improved under the low pH range.

DOI： 10.1039/d1nj01181b

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.mcat.2021.111669

Publishing type：Research paper (scientific journal)  

Visible-light driven CO reduction to formate with the system consisting of water-soluble zinc tetraphneylporphyrin tetrasulfonate (ZnTPPS), formate dehydrogenase from Candida boidinii (CbFDH) and 1-nicotinamidethy-1’-methyl-4,4’- bipyridinium salt (NEMBP) in the presence of triethanolamine (TEOA) as an electron donor was investigated. NEMBP was prepared as the 4,4’-BP with the nicotinamide-group to promote the improvement of affinity with CbFDH. The properties of NEMBP were characterized by photochemical and electrochemical methods. In order to evaluate the affinity between cation radical of NEMBP (NEMBP ), as a co-enzyme and CbFDH, the energy level based on simple docking simulation and density functional theory were estimated. It was speculated that NEMBP could bind near the substrate binding pocket of CbFDH as well as NAD by docking simulation. In the visible-light driven NEMBP reduction with the sensitization of ZnTPPS in the presence of TEOA, the yield for reduction of NEMBP to NEMBP was estimated to be 80%. In the CO reduction to formate with the system consisting of TEOA, ZnTPPS, NEMBP and CbFDH, the turnover numbers of NEMBP and CbFDH were estimated to be 0.14 and 1.53 h , respectively. 2 2 +. +. + +. −1

DOI： 10.1002/cnma.202100045

Other URL： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/cnma.202100045

Publishing type：Research paper (scientific journal)  

<p>Visible-light-driven CO₂ reduction to formate with a system consisting of water-soluble zinc porphyrin, formate dehydrogenase from <italic>Candida boidinii</italic> and 1-amino-1′-carbamoyl-4,4′-bipyridinium salt as an electron mediator in the presence of triethanolamine was developed.</p>

DOI： 10.1039/d1nj00889g

Publishing type：Research paper (scientific journal)  

<p>ギ酸は毒性が低く取り扱いが容易なため，水素キャリアとして注目されている。 本論文では，ポリビニルピロリドンによって分散された白金微粒子（Pt-PVP）を触媒としたギ酸分解に基づく選択的水素生成機構について，同位体標識したギ酸からの水素生成に対する速度論的同位体効果，水素生成に対する活性化エネルギーのpH依存性，およびギ酸の脱水に基づく一酸化炭素生成から議論した。同位体標識したギ酸を使用した水素生成に対する速度論的同位体効果の結果から，ギ酸が水素と二酸化炭素とに分解される過程の律速段階は，Pt-PVPに吸着したヒドリド種と溶液中のプロトンからの水素生成であることが示唆された。次に，Pt-PVPを触媒とするギ酸からの水素生成に対する活性化エネルギーのpH依存性を調べた結果，pH 2.5と3.5では差は見られないものの，pH 1.8では活性化エネルギーが低減されることが分かった。一方で，pH 1.8では水素生成量は他のpH領域と比較して著しく低下したことから，Pt-PVPを触媒とするギ酸分解に基づく水素生成は，ギ酸イオン濃度に強く依存することが示唆された。これは，pH 2.5と3.5ではPt-PVPを触媒とする水素生成の律速段階が，白金微粒子上の水素と溶液中のプロトンからの水素生成であるのに対して，pH 1.8ではその段階が白金微粒子へのギ酸イオンの吸着あるいは微粒子上でのギ酸塩のC–H結合開裂であることを示している。さらに，Pt-PVPはギ酸を選択的に水素と二酸化炭素に分解する触媒として作用し，ギ酸の脱水による一酸化炭素生成は進行しないことが分かった。</p>

DOI： 10.1627/jpi.64.203

CiNii Article

Publishing type：Research paper (scientific journal)  

<p>The pH dependence of the electron-donating ability of triethanolamine in a visible-light driven H₂ production system of water-soluble zinc porphyrin, methylviologen and colloidal platinum nanoparticles dispersed with polyvinylpyrrolidone (Pt-PVP) was investigated using a redox potential/pH diagram.</p>

DOI： 10.1246/cl.210518

CiNii Article

Publishing type：Research paper (scientific journal)  

<p>Mechanism for formate dehydrogenase from <italic>Candida boidinii</italic> catalyzed CO₂ reduction to formate with the cation radical of a 4,4′-bipyridinium salt with an ionic substituent as a co-enzyme was clarified by theoretical studies.</p>

DOI： 10.1039/d0cp05261b

Publishing type：Research paper (scientific journal)  

<p>Visible-light-driven CO₂ reduction to formate with water-soluble zinc tetraphenylporphyrin tetrasulfonate, formate dehydrogenase from <italic>Candida boidinii</italic> and methylviologen in the presence of triethanolamine as an electron donor in an ionic liquid.</p>

DOI： 10.1039/d0ra08594d

Publishing type：Research paper (scientific journal)  

<p>The interaction between the single-electron reduced carbamoyl-modified-4,4-bipyridinium salt and CbFDH in the CO₂ reduction to formate is elucidated by enzymatic kinetic analysis, the docking simulation and density functional theory calculation.</p>

DOI： 10.1039/d0nj04375c

Publishing type：Research paper (scientific journal)  

<p>ME is an attractive biocatalyst for building carbon–carbon bonds through carboxylation of pyruvate with CO₂. The carboxylation of pyruvate with CO₂ was promoted by adding a trivalent metal ion. In particular, Al³⁺ accelerates ME-catalyzed carboxylation of pyruvate with CO₂.</p>

DOI： 10.1039/d0nj03449e

Publishing type：Research paper (scientific journal)  

<p>The light-driven CCU with molecular and enzyme-based catalysts for C–H bond activation and building C–C bonds with CO₂ and photofunctional materials are introduced and discussed the outline of life cycle assessment of a typical system for light-driven CCU systems.</p>

DOI： 10.1039/d0gc01796e

Publishing type：Research paper (scientific journal)  

<p>By using Pt nanoparticles dispersed by polyvinylpyrrolidone and cationic biopolymer, poly(<sc>l</sc>-lysine) (Pt–PVP/PLL), the highly selective H₂ production based on formate decomposition was accomplished compared with that of Pt–PVP.</p>

DOI： 10.1039/d0nj02032j

Publishing type：Research paper (scientific journal)  

<p>The two-electron supply process using single-electron reduced methylviologen as a co-enzyme in the reduction process of CO₂ to formate catalyzed by formate dehydrogenase from <italic>Candida boidinii</italic> was clarified by experimental and quantum chemical analyses.</p>

DOI： 10.1039/d0cp02665d

Publishing type：Research paper (scientific journal)  

<p>It was found that CbFDH was catalytically reduce only carbon dioxide to formate among the three types of carbonate species, carbon dioxide, bicarbonate and carbonate for the first time.</p>

DOI： 10.1039/d0nj01183e

Publishing type：Research paper (scientific journal)  

<p>To clarify the HCOOH decomposition into H₂ and CO₂ mechanism with Pt-PVP, a pH or HCOO⁻ concentration dependence of H₂ production rate with Pt-PVP, IR spectra was studied and the possible catalytic mechanism of H₂ production was proposed.</p>

DOI： 10.1039/d0se00363h

Publishing type：Research paper (scientific journal)  

DOI： 10.1002/cctc.201901563

Publishing type：Research paper (scientific journal)  

DOI： 10.1002/celc.201901453

Publishing type：Research paper (scientific journal)  

DOI： 10.1039/c9pp00176j

PubMed

Publishing type：Research paper (scientific journal)  

© 2019 The Chemical Society of Japan. Selective hydrogen production from formic acid with platinum nano-cluster dispersed by various protective polymer based agents polyvinylpyrrolidone (Pt-PVP) or polyacrylic acid (Pt-PAA) is attempted. The ratio of hydrogen to CO2 was estimated to be c.a. 1.0 (stoichiometric ratio) under the argon-saturated buffer solution containing formic acid with Pt-PVP.

DOI： 10.1246/cl.190311

CiNii Article

Publishing type：Research paper (scientific journal)  

© Published under licence by IOP Publishing Ltd. Anti-Stokes fluorescence from chlorophyll a molecules dispersed in diethyl ether has been observed. From the excitation power dependence of the fluorescence spectrum, it is concluded that the anti-Stokes fluorescence appears via the linear optical process. To consider the relationship between the observed spectral shape and vibrational modes, the model spectral density has been determined based on the Raman spectrum and real-time coherent vibrational oscillation signals. The absorption spectrum observed in the experiment was well reproduced by the calculation, indicating the validity of the model spectral density. The involvement of the low-frequency vibrational modes in the anti-Stokes fluorescence process is discussed.

DOI： 10.1088/1742-6596/1220/1/012043

Publishing type：Research paper (scientific journal)  

© Published under licence by IOP Publishing Ltd. Nonlinear optical responses of β-carotene were investigated upon excitation using chirped pulses. We especially focus on spectrally resolved transient grating (TG) signals to discuss the influence of the spectral chirp over a wide spectral range. A significant change in the TG signal was observed when negatively chirped pulses were used. The experimental results were qualitatively reproduced by employing the Brownian oscillator model. The relationship between the wave packet motion in the excited state and spectral chirp is discussed. It is concluded that the third order nonlinear optical response reflects the competition between the spectral chirp and the energy separation of the potential curves.

DOI： 10.1088/1742-6596/1220/1/012045

Publishing type：Research paper (scientific journal)  

© 2019 American Chemical Society. Malate dehydrogenase (oxaloacetate-decarboxylating) commonly named malic enzyme (ME) from chicken liver (EC 1.1.1.40) catalyzes a reaction introducing CO2 as a carboxy-group to pyruvate to form malate via oxaloacetate in the presence of the coenzyme NADPH, and is an attractive biocatalyst for building C-C bonds using CO2 as a chemical carbon feedstock. We previously discovered that multielectron reduced diphenylviologen derivatives (PVs) can act as an artificial coenzyme for ME, replacing the expensive NADPH (natural coenzyme), in the formation of malate. In this Letter, the kinetic parameters of oxaloacetate production based on building C-C bonds of a coupling pyruvate and CO2 with water-soluble PVs, double-electron reduced 1,1′-bis(p-carboxyphenyl)-4,4′-bipyridinium dichloride (PCV0) and ME were determined with the analysis of enzymatic kinetics for the first time. PCV0 acts as a Lewis base and is involved in oxaloacetate production via C-H bond activation and carboxylation of pyruvate by CO2.

DOI： 10.1021/acssuschemeng.9b00081

Publishing type：Research paper (scientific journal)  

DOI： 10.1039/c8nj02211a

Publishing type：Research paper (scientific journal)  

<p>Effective light-driven conversion of CO₂ to formic acid with a hybrid system consisting of photocatalyst TiO₂ nanoparticle (P25), methylviologen (MV²⁺) as an electron mediating molecule and biocatalyst formate dehydrogenase (FDH) in the presence of triethanolamine (TEOA) as an electron donating molecule was investigated. After 120 min irradiation with a Xe lamp (>300 nm), 152 µM of formic acid was produced in a CO₂ saturated buffer solution containing TEOA (300 mM), TiO₂ nanoparticles (6.8 mg·L⁻¹), MV²⁺ (0.5 mM) and FDH (7.5 µM).</p>

DOI： 10.1246/cl.180731

CiNii Article

Publishing type：Research paper (scientific journal)  

DOI： 10.1515/pac-2018-0402

Publishing type：Research paper (scientific journal)  

DOI： 10.1039/c8nj03478h

Publishing type：Research paper (scientific journal)   Kind of work：Single Work  

© 2018 The Royal Society of Chemistry. Visible-light driven redox systems have been attracting significant research attention due to their ability to produce hydrogen and reduce and utilize CO2for the production of solar fuels and chemicals. Generally, visible-light driven redox systems consist of an electron donor, a photocatalytic dye, an electron mediator and a catalyst. One of the important components in visible-light driven redox systems is an effective catalyst for hydrogen production and reduction and utilization of CO2. The catalysts used in visible-light driven redox systems are classified into metal nanoparticles, molecular catalysts and biocatalysts. Among them, biocatalysts are promising due to their excellent reaction and substrate selectivity, especially for the reduction and utilization of CO2, which is remarkably higher than that of other catalysts. Among the biocatalysts for CO2reduction and utilization, NAD(P)+-dependent dehydrogenases, which are commercially available, are widely used in visible-light driven redox systems. Formate dehydrogenase (FDH) from Candida boidinii is a typical NAD(P)+-dependent dehydrogenase for the visible-light driven redox reduction of CO2to formate. Furthermore, the addition of commercially available aldehyde (aldDH), formaldehyde (FldDH) and alcohol (ADH) dehydrogenase to this system results in the reduction of CO2to methanol via formate and formaldehyde as intermediates in visible-light driven redox systems. Furthermore, NAD(P)+-dependent dehydrogenases for decarboxylation are also commercially available and widely used for the visible-light driven formation of carbon-carbon bonds from CO2and organic molecules. Malic enzyme (ME) from chicken liver is a typical NAD(P)+-dependent dehydrogenase with decarboxylating ability for the visible-light driven production of malate, which is based on the formation of carbon-carbon bonds from CO2and pyruvate. In this review, visible-light driven CO2reduction and utilization systems involving the photoreduction of NAD(P)+and biocatalysts are introduced. Furthermore, visible-light driven CO2reduction and utilization systems involving the photoreduction of bipyridinium salt (viologen)-based electron mediators and biocatalysts also are introduced. In particular, the simplification of visible-light driven CO2reduction and utilization systems by utilizing viologen-based electron mediators and the improvement in their efficiency without changing the structure of the biocatalyst are also discussed.

DOI： 10.1039/c8se00209f

Publishing type：Research paper (scientific journal)  

<p>Formate dehydrogenase (FDH) is a useful biocatalyst for CO₂ reduction to formic acid in a photoredox system consisting of a photosensitizer and an electron carrier. The electron carrier, single-electron reduced 2,2′-bipyridinium salts (2,2′-BP²⁺s) act as the co-enzyme for FDH in the reaction of CO₂ to formic acid. An advantage of 2,2′-BP²⁺s is the easy change of structural geometry and the various single-electron reduction potentials. For further improvement of CO₂ reduction catalytic activity of FDH, various 2,2′-BP²⁺s were synthesized as effective artificial co-enzymes for FDH. The effect of the structural geometry and the single-electron reduction potential in the single-electron reduced form of 2,2′-BP²⁺s on the CO₂ reduction catalytic activity of FDH was studied by enzymatic kinetic analysis in detail for the first time. Especially, the catalytic efficiency, <i>k_cat</i>/<i>K</i>_m value of the single-electron reduced 1,1′-ethylene-2,2′-bipyridinium salt was c.a. 126 times larger than that of native co-enzyme, NADH. These results showed that catalytic activity of FDH can be manipulated with complete control by using 2,2′-BP²⁺ without changing the structure of FDH and has opened a new avenue for the approach of NAD⁺/NADH redox free system with FDH using an inexpensive small electron carrier molecule.</p>

DOI： 10.1246/bcsj.20180013

CiNii Article

Publishing type：Research paper (scientific journal)   Kind of work：Single Work  

© 2018 Elsevier Ltd. All rights reserved. Carbon dioxide, CO2reduction and utilization for organic compounds synthesis are the potential technologies in environmental science and technology. In order to establish efficient CO2utilization technologies, an effective catalyst for CO2reduction and utilization is necessary. Among various catalysts, the biocatalyst is one of promising catalysts because it has excellent selectivity for the reaction and substrate. In this review, focusing on biocatalyst "formate dehydrogenase FDH" catalyzing CO2reduction to formic acid, representative examples of properties, types, structure of active-site of FDH and, reaction mechanism of formic acid oxidation and CO2reduction with FDH are outlined. A genetic engineering modified FDH and FDH immobilized various support for improving CO2reduction catalytic activity also are introduced. Moreover, chemical and electrochemical system of CO2reduction to formic acid with FDH, aqueous homogenous system of visible-light driven CO2reduction to formic acid with FDH and device for visible-light driven CO2reduction to formic acid with FDH are also introduced as an application of FDH.

DOI： 10.1016/j.jcou.2018.06.022

Publishing type：Research paper (scientific journal)  

© 2018 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. Aerobic photosynthesis in green plants, cyanobacteria, and micro-algae has two important sites in the integral-membrane photoactive complexes, photosystems I (PSI) and II (PSII). These systems are assembled into thylakoid membranes. Thylakoid membranes with oxygen-evolution activity owing to PSII can be used in visible-light driven water photolytic materials. In this work, a new visible-light driven electrochemical biofuel-based cell consisting of the thylakoid membrane of microalgae Spirulina platensis immobilized on a nanocrystalline TiO2layer electrode as a photoanode, a formate dehydrogenase (FDH)/viologen co-immobilized electrode as a cathode, and a CO2-saturated buffer solution as the redox electrolyte, was developed. The actual short-circuit photocurrent of this cell was estimated to be ca. 50 μA cm-2. Formic acid and oxygen were produced in this biofuel cell, while generating electricity from irradiated visible light. The ratio of formic acid to oxygen produced in the biofuel cell after continuous irradiation was estimated to be ∼2. Thus, formic acid and oxygen were produced stoichiometrically in this visible-light driven electrochemical biofuel cell. Thus, a new biofuel cell system with the functions of a solar cell and the ability of CO2conversion was developed.

DOI： 10.1039/c8nj01118d

Publishing type：Research paper (scientific journal)  

© 2017 Elsevier B.V. Photochemical and enzymatic production of methanol from CO2was investigated with the system formate (FDH), aldehyde (AldDH) and alcohol (ADH) dehydrogenases, and methylviologen (MV2+) photoreduction by the visible light photosensitization of organo-photocatalyst, water-soluble porphyrin, tetraphenylporphyrin tetrasulfonate (H2TPPS) in the presence of triethanolamine (TEOA) as an electron donating reagent. To improve the methanol production from CO2, the kinetic parameters for methanol production with ADH and dithionite-reduced MV2+were clarified. When the sample solution consisting of H2TPPS (100 μM), MV2+(2.0 mM), TEOA (0.3 M), FDH (2.0 μM), AldDH (2.0 μM) and ADH (2.0 μM) in CO2saturated 50 mM sodium pyrophosphate buffer was irradiated, continuous methanol production from CO2was observed and methanol concentration produced was estimated to be 6.8 μM after 100 min irradiation.

DOI： 10.1016/j.cattod.2017.12.029

Publishing type：Research paper (scientific journal)  

© 2017 Elsevier B.V. Formate dehydrogenase (FDH) is an attractive biocatalyst for converting CO2to formic acid in ambient conditions. FDH is applied to the catalyst for the visible-light induced CO2– formic acid conversion system consisting of an electron donor, a photosensitizaer and an electron carrier. For improvement of the formic acid production efficiency with this system, the enhancement of electron relay processes among a photosensitizer, an electron carrier and FDH has been needed. We aimed to solve this problem by developing novel electron carrier based on the viologen derivative instead of methylviologen (MV), widely used as an electron carreir. In this study, viologen derivatives with carbamoyl group, 1,1′-dicarbamoylmethyl-4,4′-bipyridinium diiodide (CV) and 1-carbamoylmethyl-1′-methyl-4,4′-bipyridinium diiodide (CMV) were synthesized and applied to the electron carrier for photoinduced CO2-formic acid conversion system consisting of triethanolamine, water-soluble zinc porphyrin and FDH. By using CV and CMV, the effective formic acid production in the system of water-soluble zinc porphyrin and FDH was improved compared with that of MV.

DOI： 10.1016/j.jphotochem.2017.09.044

Publishing type：Research paper (scientific journal)  

© 2017 Elsevier B.V. Singlet and triplet excited states dynamics of the photosynthetic pigment chlorophyll a in various solvents have been investigated by sub-ns pump-probe spectroscopic measurements with a sub-ns time resolution and a temporal window up to 400 μs. The singlet and triplet lifetimes of chlorophyll a were determined respectively to be 5.2–7.0 ns and 1.2–12 μs, depending on solvents. On a basis of a global analysis of time-resolved spectroscopic data, we estimated an yield of the intersystem crossing from the singlet to triplet excited states chlorophyll a to be about 30% depending not on surrounding environments. The value is much lower than the previously reported values.

DOI： 10.1016/j.jphotochem.2017.09.046

Publishing type：Research paper (scientific journal)  

© 2017 Elsevier B.V. Molecular conversion reaction system containing a dye and a biocatalyst catalyzing a reaction of a carbon–carbon bond formation from CO2as a feedstock were constructed. For example, NADP-malic enzyme (ME, EC1.1.1.40) catalyzes the reaction of introducing CO2as a carboxy group to pyruvate (C3 compound) to form malate (C4 compound) via oxaloacetate in the presence of natural co-enzyme NADPH. In a recent study, visible light-induced oxaloacetate production from pyruvate and CO2with the system consisting an electron donor, a photosensitizer, diphenylviologen (PV2+) derivative as an electron mediator and ME was reported. However, the visible light-induced reduction properties of PV2+with water-soluble Zn porphyrin have not been clarified. In this study, chemical and photo-redox properties of PV2+were studied. In addition, to produce malate, CO2saturated reaction solution containing triethanolamine, tetraphenylporphine tetrasulfonate (H2TPPS), pyruvate, PV2+and ME in the presence of Mg2+, co-factor for ME was irradiated with visible-light, the oxaloacetate and malate were produced.

DOI： 10.1016/j.jphotochem.2017.09.045

Publishing type：Research paper (scientific journal)  

DOI： 10.1039/c7pp00277g

Publishing type：Research paper (scientific journal)  

DOI： 10.11523/sekiyu.2018f.0_102

CiNii Article

Publishing type：Research paper (scientific journal)  

DOI： 10.1039/c7se00255f

Publishing type：Research paper (scientific journal)  

DOI： 10.1039/c6fd00212a

Publishing type：Research paper (scientific journal)   Kind of work：Single Work  

<p>In this review, the recent studies on 1) the visible-light-induced reduction of CO₂ to formic acid catalyzed by formate dehydrogenase (FDH) via the reduction of a 4,4′- or 2,2′-bipyridinium salt (BP²⁺) by a photosensitizer, 2) the electrochemical properties of BP²⁺, and 3) the enzymatic kinetic properties of the interaction between the reduced forms of BP²⁺ and FDH are reviewed. Moreover, visible-light-induced biocatalytic C–C bond formation using CO₂ as a feedstock via photoreduction of the phenylviologen derivative is introduced.</p>

DOI： 10.1246/cl.161189

CiNii Article

Publishing type：Research paper (scientific journal)  

DOI： 10.1002/cctc.201601188

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DOI： 10.1021/acsami.6b12744

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DOI： 10.1007/s11164-016-2662-0

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DOI： 10.1007/s11164-016-2660-2

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DOI： 10.1007/s11164-016-2661-1

Publishing type：Research paper (scientific journal)  

<p>Formate dehydrogenase (FDH) is an attractive biocatalyst for CO₂ reduction. The reduced form of methylviologen acts as an artificial coenzyme for FDH. For further improvement in the CO₂ reduction catalytic activity of FDH, a viologen derivative with two amino groups, 1,1′-diaminoethyl-4,4′-bipyridinium salt (DA²⁺), was synthesized as the effective artificial coenzyme for FDH. By enzyme kinetic analysis, the catalytic efficiency, i.e., <i>k</i>_cat/<i>K</i>_m value of the reduced form of DA²⁺ was estimated to be more than 560 times larger than that of NADH, the natural coenzyme for FDH.</p>

DOI： 10.1246/cl.160687

CiNii Article

Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s11164-016-2658-9

Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s11164-016-2659-8

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DOI： 10.1016/j.apcatb.2015.06.051

Publishing type：Research paper (scientific journal)  

The kinetic properties of the conversion of CO2 to formic acid with formate dehydrogenase (FDH) using some dithionite-reduced 2,2'-bipyridinium salts (1,1'-ethylene-2,2'-bipyridinium dibromide diquat and 1,1'-dimethyl-2,2'-bipyridinium dichloride) as an artificial co-enzyme were studied. By using the reduced form of diquat, the effective CO2 reduction to formic acid with FDH is accomplished. The catalytic efficiency, kcat / Km value of the reduced form of diquat was c.a. 126 times larger than that of NADH.

DOI： 10.1246/cl.160389

CiNii Article

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jphotochem.2015.06.026

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ijhydene.2015.01.158

Publishing type：Research paper (scientific journal)  

The kinetic properties of the conversion of CO₂ to formic acid with formate dehydrogenase (FDH) using dithionite-reduced methylviologen as an artificial co-enzyme were studied. The catalytic production of CO₂ from formic acid by FDH was suppressed using methylviologen as an artificial co-enzyme. In contrast, compared to the natural co-enzyme NADH, dithionite-reduced methylviologen was a more effective co-enzyme in the conversion of CO₂ to formic acid with FDH.

DOI： 10.1246/cl.150425

CiNii Article

Publishing type：Research paper (scientific journal)  

DOI： 10.1142/S1088424615500406

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ijhydene.2014.06.135

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DOI： 10.1007/s11164-014-1831-2

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DOI： 10.1007/s11164-014-1822-3

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DOI： 10.1007/s11164-014-1833-0

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DOI： 10.1007/s11164-014-1832-1

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Publishing type：Research paper (scientific journal)  

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Publishing type：Research paper (scientific journal)  

An optical oxygen sensor was developed as a pressure-sensitive paint (PSP) to measure time-varying surface pressure in aerodynamic testing. A silica nanoparticle dispersion (slurry) was used as the binder for the sensor, with a pressure-sensitive dye dissolved in the slurry. The dye slurry was deposited onto arbitrary surfaces via spray coating. Thin porous silica films were successfully formed without any organic additives. The pressure and temperature sensitivity of common pressure-sensitive dyes platinum tetra(pentafluorophenyl) porphyrin (PtTFPP)and tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) dichloride ([Ru(dpp)3]Cl2) with a silica/toluene slurry were tested, in addition to the temporal response. The pressure sensitivity was -0.94/kPa for PtTFPP and -0.64/kPa for [Ru(dpp)3]2+, which was comparable to the sensitivity of common PSPs. The sensor had good photostability, although it exhibited substantial temperature sensitivity (ca. 1.5/°C). The response time was less than 0.1 ms for a step rise in pressure obtained using a shock tube. © 2012 Published by Elsevier B.V.

DOI： 10.1016/j.snb.2012.04.049

Publishing type：Research paper (scientific journal)  

Solar fuels, such as hydrogen gas produced from water and methanol produced from carbon dioxide reduction by artificial photosynthesis, have received considerable attention. In natural leaves the photosynthetic proteins are well-organized in the thylakoid membrane. To develop an artificial leaf device for solar low-carbon fuel production from CO 2, a chlorophyll derivative chlorin-e 6 (Chl-e 6; photosensitizer), 1-carboxylundecanoyl-1′-methyl-4,4′-bipyrizinium bromide, iodide (CH 3V(CH 2) 9COOH; the electron carrier) and formate dehydrogenase (FDH) (the catalyst) immobilised onto a silica-gel-based thin layer chromatography plate (the Chl-V-FDH device) was investigated. From luminescence spectroscopy measurements, the photoexcited triplet state of Chl-e 6 was quenched by the CH 3V(CH 2) 9COOH moiety on the device, indicating the photoinduced electron transfer from the photoexcited triplet state of Chl-e 6 to the CH 3V(CH 2) 9COOH moiety. When the CO 2-saturated sample solution containing NADPH (the electron donor) was flowed onto the Chl-V-FDH device under visible light irradiation, the formic acid concentration increased with increasing irradiation time. © 2012 The Royal Society of Chemistry.

DOI： 10.1039/c1fd00097g

PubMed

Publishing type：Research paper (scientific journal)  

A light-harvesting (LH) antenna complex II, LHCII, isolated from spinach was immobilized onto an indium tin oxide (ITO) electrode with dot patterning of 3-aminopropyltriethoxysilane (APS) by utilizing electrostatic interactions between the cationic surface of the electrode and the anionic surface of stromal side of the LHCII polypeptide. Interestingly, the illumination of LHCII assembled onto the ITO electrode produced a photocurrent response that depends on the wavelength of the excitation light. Further, LHCII was immobilized onto a TiO2nanostructured film to extend for the development of a dye-sensitized biosolar cell system. The photocurrent measured in the iodide/tri-iodide redox system of an ionic liquid based electrolyte on the TiO2system showed remarkable enhancement of the conversion efficiency, as compared to that on the ITO electrode. © 2012 American Chemical Society.

DOI： 10.1021/mz200163e

Publishing type：Research paper (scientific journal)   Kind of work：Single Work  

Models of photosynthesis mimetic systems, the so-called artificial photosynthesis systems, have been investigated since the 1970s for the purpose of tapping solar energy. With the deterioration of the global environment in the 21st century, attributed to global warming and greenhouse gas emissions, it has become imperative to identify new fuel sources such as solar energy to replace fossil fuels. Among the new fuel production systems, those involving the use of solar energy have attracted attention; examples are systems that produce hydrogen through water photolysis and those that produce methanol by CO 2 reduction with the aid of an artificial photosynthesis system. As hydrogen and methanol are low-carbon fuels (the emission of CO 2 from the combustion of these fuels is low), they are considered to be alternatives to fossil resources. In this review, solar fuel production systems consisting of an artificial photosynthesis system, a catalyst, and an enzyme are discussed. These systems are expected to help in reducing CO 2 and to promote the use of low-carbon fuels in the future. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/cctc.201000293

Publishing type：Research paper (scientific journal)   Kind of work：Single Work  

Methanol synthesis from CO 2 with formate dehydrogenase, aldehyde dehydrogenase and alcohol dehydrogenase via the artificial photosynthesis based on the photoreduction of methylviologen using water soluble zinc porphyrin photosensitization was developed and the amount of methanol produced was 0.55 μM after 4 h irradiation.

Publishing type：Research paper (scientific journal)  

Cellulase obtained from Aspergillus niger was used to hydrolyze a mixture of saccharides containing sucrose, maltose, and cellobiose; the reduced form of nicotinamide-adenine dinucleotide (NAD+), which is NADH, was produced during hydrolysis of the mixture of saccharides in the presence of NAD+and glucose dehydrogenase (GDH). We have developed a visible-light-induced enzymatic biohydrogen production system involving the combination of cellulase-mediated hydrolysis of the mixture of saccharides and hydrogen production by platinum nanoparticles using photosensitization of Mg chlorophyll-a (Mg Chl-a). Continuous production of hydrogen gas was observed when the reaction mixture containing saccharides, cellulase, GDH, NAD+, Mg Chl-a, methylviologen (MV2+, an electron donor), and platinum nanoparticles was irradiated by visible light. After 120 min of irradiation, the amount of hydrogen produced from the mixture of saccharides was approximately 2.8 μmol. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2010.04.030

Publishing type：Research paper (scientific journal)  

To develop the visible light-induced hydrogen and oxygen production based on the water photolysis, 2,6-dichloroindophenol (DCIP) reduction based on the photoinduced water oxidation with oxygen evolved centre (OEC) of PSII in photosynthesis organ, grana from spinach was studied. It noted that manganese-calcium (4Mn-Ca) cluster consisted of four manganese and one calcium ions in OEC, and the role and effect of manganese (III) and calcium ions on the DCIP reduction were investigated. By addition of manganese (III) acetate up to 80 μmol dm-3, the concentration of the reduced DCIP with irradiation was increased compared with the system in the absence of manganese (III) acetate. The activity of DCIP reduction in the presence of 80 μmol dm-3manganese (III) acetate was 4.7 times higher than that in the absence of manganese (III) acetate. This result shows that the DCIP photoreduction with grana was promoted by addition of manganese (III) ion. In contrast, the activity of DCIP reduction in the presence of 120 μmol dm-3manganese (III) acetate was 1.5 times higher than that in the absence of manganese (III) acetate, indicating that photoreduction of DCIP activity of grana was inhibited under higher concentration of manganese (III) ion or acetate anion. By addition of 80 μmol dm-3calcium chloride, on the other hand, 5.9 μmol dm-3of reduced DCIP was produced and the reduction ratio of the reduced DCIP to DCIP was 8.6% after 240 min irradiation. The activity of DCIP reduction in the presence of 80 μmol dm-3calcium chloride was almost the same in the absence of calcium chloride. This result shows the no effect on the DCIP photoreduction based on the water oxidation with grana by addition of calcium ion. © 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apcatb.2010.03.018

Publishing type：Research paper (scientific journal)  

To develop a photoinduced hydrogen production system based on an artificial photosynthesis model, the anionic water-soluble carotenoid dye crocetin, which has two carboxylate groups (a π electron conjugated polyene material with a carbon number of 20), electrostatically immobilized onto the surface of cationic surfactant cetyltrimethylammonium bromide (CTAB) micelles that included Mg chlorophyll-a and b (MgChl-a and b) (Cro/MgChl), was prepared, and its photochemical properties were studied using UV-vis absorption and fluorescence spectroscopy. The fluorescence of MgChl-a and b was induced, with the excitation wavelength attributed to the absorption band of crocetin, indicating that a photoinduced energy transfer from the photoexcited state of crocetin to MgChl-a and b occurs via the CTAB micelle interface. The photostability of MgChl-a and b in Cro/MgChl was investigated under continuous visible irradiation. After 60 min of irradiation, the absorbance at 660 nm due to MgChl-a and b in Cro/MgChl and MgChl-a/b, which did not contain crocetin, decreased by 3.0% and 17%, respectively. Little photoinduced decomposition of the crocetin moiety of Cro/MgChl was observed. These results indicate that the photoinduced decomposition rate of MgChla/ b in Cro/MgChl against irradiation was suppressed by the crocetin molecule on the surface of the micelles. An effective hydrogen production system in the presence of NADH as an electron donor, methylviologen (MV2+) as an electron carrier, and platinum colloid as a hydrogen producing catalyst under visible light irradiation was developed using Cro/MgChl as a photosensitizer (3.6 μmol in 3 h), which was found to be better than using MgChl-a/b without crocetin (2.1 μmol in 3 h). © 2009 American Chemical Society.

DOI： 10.1021/jp900063r

Publishing type：Research paper (scientific journal)  

We studied the photochemical and enzymatic synthesis of methanol from HCO3-using formate dehydrogenase (FDH) isolated from Candida boidinii, aldehyde dehydrogenase (AldDH) and alcohol dehydrogenase (ADH) isolated from yeast, and the photoreduction of methyl viologen (MV2+) by the visible-light sensitization using zinc tetraphenylporphyrin tetrasulfonate (ZnTPPS) in the presence of triethanolamine (TEOA). When a sample solution containing ZnTPPS, MV2+, FDH, AldDH, ADH, TEOA, and NaHCO3in potassium phosphate buffer solution (pH 8) was irradiated, the amount of methanol produced increased with the irradiation time. After irradiation for 3 h, 4.5 μmol dm-3of methanol was produced from 100 μmol dm-3NaHCO3. The conversion ratio of HCO3-to methanol was approximately 4.5%. This result indicates that a system for the photochemical synthesis of methanol from HCO3-can be developed by using three dehydrogenases (FDH, AldDH, and ADH) and for the photoreduction of MV2+through the photosensitization of ZnTPPS in aqueous media. © 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apcatb.2008.08.008

Publishing type：Research paper (scientific journal)  

Oxygen-monitoring techniques are applied to various fields, such as chemicals, deep sea environment, fluid dynamics, clinical analysis and environmental monitoring. Recently, a variety of devices and sensors based on phosphorescence or photoexcited state quenching of porphyrin molecules have been developed to measure oxygen concentration on the solid surface. Many optical oxygen sensors are composed of porphyrins (platinum(II), palladium(II), zinc(II), metal-free, etc.) dispersed in oxygen-permeable polymer film or directly immobilized onto solid surface via chemical or physical adsorption. Oxygen-sensing systems are classified into four types: (1) phosphorescence intensity change, (2) phosphorescence lifetime change, (3) change of lifetime of photoexcited triplet state, and (4) intensity change of absorption of photoexcited triplet state. In this review, the properties of various optical oxygen-sensing devices using porphyrins and sensing system are introduced. © 2009 World Scientific Publishing Company.

DOI： 10.1142/S1088424609001455

Publishing type：Research paper (scientific journal)  

Photochemical and enzymatic synthesis of formic acid was investigated from HCO3− with formate dehydrogenase (FDH) from Saccharomyces cerevisiae and reduced methylviologen (MV2+) produced by the visible light photosensitization of zinc tetrakis(4-methylpyridyl) porphyrin (ZnTMPyP) in the presence of triethanolamine (TEOA) as an electron donating reagent. Irradiation of a solution containing TEOA, ZnTMPyP, MV2+, NaHCO3 and FDH in potassium phosphate buffer, with visible light resulted in formic acid production and HCO3− consumption. The optimum FDH activity was 20 units and the amount of formic acid and the yield of HCO3− to formic acid after 4 h irradiation were estimated to be 50 μmol • dm−3 and 5.0%, respectively. © 2009, The Japan Petroleum Institute. All rights reserved.

DOI： 10.1627/jpi.52.322

Publishing type：Research paper (scientific journal)  

Photovoltaic conversion using photosynthesis organ Grana from Spinach adsorbed nanocrystalline TiO2layer onto ITO glass (OTE) electrode (Grana/TiO2electrode) is developed. The shape of absorption spectrum of the Grana/TiO2electrode is almost the same that of Grana solution. Absorption maxima of Grana/TiO2electrode are observed at 450, 480 and 680 nm attributed to carotenoid and chlorophyll molecules. This result suggests that Grana are adsorbed onto nanocrystalline TiO2layer onto OTE. The photocurrent responses of Grana/TiO2elec-trodes are measured using acetonitrile with 0.1 mol dm-3tetrabutylammonium hexafluorophospate as a redox electrolyte in the presence and absence of water with 100 mWcm-2irradiation. Photocurrent of Grana/TiO2electrode increases using the redox electrolyte containing water. Moreover, the photocurrent responses of Grana/TiO2electrodes with monochromatic light (680 nm attributed to absorption band of photosystem II with oxygen evolved complex) irradiation are measured using acetonitrile with 0.1 mol dm-3tetrabutylammonium hexafluorophospate as a redox electrolyte in the presence and absence of water. Photocurrent of Grana/TiO2electrode using the redox electrolyte containing water only is observed, indicating that the evolved oxygen from water with photosystem II in Grana onto nanocrystalline TiO2layer electrode by 680 nm irradiation is reduced to water with catalytic activity of platinum electrode.

DOI： 10.5796/electrochemistry.77.862

Publishing type：Research paper (scientific journal)  

Photoinduced hydrogen production via the photoreduction of methyl viologen (MV2+) using the sensitization of light-harvesting chlorophyll a/b-protein complex of photosystem II (LHCII) from spinach in the presence of platinum nanoparticles and NADH is developed.

DOI： 10.1246/bcsj.82.93

Publishing type：Research paper (scientific journal)  

To develop the visible light induced hydrogen and oxygen production based on the water photolysis, 2,6-dichloroindophenol (DCIP) reduction based on the photoinduced water oxidation with oxygen evolved centre (OEC) of PSII in photosynthesis organ, grana from spinach was studied. It noted that manganese cluster consisted of four manganese ions in OEC, and the role and effect of manganese(II) and (III) ions on the DCIP reduction were investigated. By addition of manganese(III) acetate up to 80 μmol dm-3, the concentration of the reduced DCIP with irradiation was increased compared with the system in the absence of manganese(III) acetate. The activity of DCIP reduction in the presence of 80 μmol dm-3manganese(III) acetate was 4.7 times higher than that in the absence of manganese(III) acetate. In contrast, the concentration of the reduced DCIP with irradiation was increased by addition of manganese(II) acetate up to 40 μmol dm-3compared with the system in the absence of manganese(II) acetate. These results show that the DCIP photoreduction with grana was promoted by addition of manganese(III) or (II) ion. © 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.catcom.2008.08.022

Publishing type：Research paper (scientific journal)   Kind of work：Single Work  

Photoinduced biohydrogen production systems, coupling saccharaides biomass such as sucrose, maltose, cellobiose, cellulose, or saccharides mixture hydrolysis by enzymes and glucose dehydrogenase (GDH), and hydrogen production with platinum colloid as a catalyst using the visible light-induced photosensitization of Mg chlorophyll-a (Mg Chl-a) from higher green plant or artificial chlorophyll analog, zinc porphyrin, are introduced. © 2008 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland.

DOI： 10.3390/ijms9071156

Publishing type：Research paper (scientific journal)  

The visible light-operated saccharide-O2biofuel cell consisting of zinc chlorin-e6(ZnChl-e6) adsorbed on nanocrystalline TiO2layer coated onto optical transparent conductive glass electrode (OTE) as an anode, platinum-coated OTE as a cathode, and the fuel solution containing sucrose as a saccharide, invertase, glucose dehydrogenase (GDH) and NAD+is studied as a new type biofuel cell. The short-circuit photocurrent (ISC) and the open-circuit photovoltage (VOC) of this cell are 9.0 μA cm-2and 415 mV, respectively. The peaks in the photocurrent action spectrum of this cell are observed at 400 and 800 nm and the incident photon-to-current efficiency (IPCE) values at 400 and 800 nm are estimated to be ca. 17.3% and 10.6%. Thus, a new type of visible light-operated saccharide-O2biofuel cell with the visible and near IR photosensitization of ZnChl-e6molecules on nanocrystalline TiO2film electrode is accomplished. © 2008 International Association for Hydrogen Energy.

DOI： 10.1016/j.ijhydene.2008.03.034

Publishing type：Research paper (scientific journal)  

Mg chlorophyll-a (MgChl-a) with imidazole-4-acetic acid (Im) as the axial ligand, MgChl-a(Im) conjugated to a nanocrystalline TiO2film onto optical transparent substrate electrode (OTE) is prepared and the photovoltaic properties of the nanocrystalline TiO2film through an axial Im ligand of MgChl-a are studied. MgChl-a conjugated to nanocrystalline TiO2film electrode is prepared by using two different methods. One is the MgChl-a conjugated to nanocrystalline TiO2film electrode using carboxyl group of Im of MgChl-a(Im) (MgChl-a(Im)/TiO2). The other is the MgChl-a conjugated to nanocrystalline TiO2film electrode using the coordination of Im immobilized onto TiO2to the axial site of MgChl-a (MgChl-a/Im-TiO2). In MgChl-a(IM)/TiO2and MgChl-a/Im-TiO2, the fluorescence of MgChl-a is effectively quenched by the electron injection from the excited singlet state of MgChl-a into the conduction band of TiO2particles via the axial ligand of Im. The photocurrent action spectra of MgChl-a(Im)TiO2, MgChl-a/Im-TiO2and MgChl-a/TiO2electrodes are similar to that of the UV-vis absorption spectra in the methanol solution and incident photon to current efficiency (IPCE) values reach a maximum around the wavelength of absorption maximum (660-680 nm). IPCE value of MgChl-a/TiO2electrode (0.65% at 680 nm) is lowest among those of MgChl-a(Im)TiO2(1.65% at 680 nm) and MgChl-a/Im-TiO2(1.74% at 660 nm) electrodes. These results indicate that MgChl-a anchored on nanocrystalline TiO2film through the axial Im ligand is the efficient visible sensitization for photovoltaic injection cell based on the nanocrystalline TiO2film electrode. Copyright © 2008 American Scientific Publishers. All rights reserved.

DOI： 10.1166/jbmb.2008.004

Publishing type：Research paper (scientific journal)  

We report on the development of a new optical glucose sensor using o-dianisidine hydrochloride (DASD), glucose oxidase (GOD), and peroxidase (POD) immobilized onto a gold nanoparticle-modified Al2O3-based thin layer chromatography (TLC) sheet for D-glucose detection based on the colorimetric change in DASD. Images of the DASD/GOD/POD-modified site of the TLC plate demonstrated color changes at various D-glucose concentrations ranging between 0 and 10-1 M. The intensity increased with increasing D-glucose concentration, indicating that the D-glucose concentration can be visually estimated using the DASD/GOD/POD-modified site of the TLC plate. A plot of the logarithm values of D-glucose concentrations against the relative intensity showed good linearity, indicating that the D-glucose concentration could be determined based on the intensity of the images of the DASD/GOD/POD-modified site of the TLC plate. Copyright © 2008 American Scientific Publishers. All rights reserved.

DOI： 10.1166/sl.2008.016

Publishing type：Research paper (scientific journal)   Kind of work：Single Work  

The solar energy conversion system based on photosynthesis is promising as alternative energy invention technology of the future. In this review, the photoenergy conversion system based on the photosensitization of major photosynthesis dye pigment molecule, chlorophyll immobilized onto titanium dioxide or assembled into surfactant micellar system are introduced. One is the photoinduced hydrogen production system with the system containing an electron donor reagent, an electron carrier reagent, hydrogen producing catalyst and chlorophyll molecule assembled in surfactant micellar system. The other one is the photovoltaic system based on the chlorophyll or chlorophyll derivative molecules immobilized onto nanocrystalline TiO2film electrode. © 2008 Bentham Science Publishers Ltd.

DOI： 10.2174/157341308783591753

Publishing type：Research paper (scientific journal)  

Here, we developed a photoinduced biohydrogen production system coupling saccharide hydrolysis with hydrogen production. A mixture of three different saccharides (sucrose, maltose, and cellobiose) was hydrolyzed by three enzymes (invertase, glucoamylase, and cellulase) and glucose dehydrogenase (GDH). Hydrogen production was performed with colloidal platinum as a catalyst, using visible light-induced photosensitization of Mg chlorophyll a (Mg Chl a). Irradiation of the sample solution containing the saccharides, enzymes, GDH, NAD+, Mg Chl a, methyl viologen (MV2+), and colloidal platinum resulted in continuous hydrogen production. Approximately 2.9 μmol hydrogen was produced after 2 h of irradiation, and the total yield was approximately 8.8%. © 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.catcom.2007.05.035

Publishing type：Research paper (scientific journal)  

Visible light-operated glucose-O2 biofuel cell consisting of chlorin-e6 metal complexes (MChl-e6,M = H2and Zn) adsorbed on TiO2coated onto Optical Transparent conductive glass Electrode (OTE) as an anode, platinum electrode as a cathode, and the solution containing glucose, Glucose Dehydrogenase and NAD+as a fuel is studied. The cells using H2Chl-e6 and Zn Chl-e6adsorbed on TiO2coated OTEs are defined as Biofuel CellH2and Biofuel CellZn. The closed-circuit photocurrent in Biofuel CellH2and Biofuel CellZn are 0.067 ± 0.003 and 0.017 ± 0.007 mA cm-2, and the open-circuit photo voltages are 503 ± 10 and 559 ± 12 mV, respectively. Copyright © 2007 Inderscience Enterprises Ltd.

DOI： 10.1504/IJGEI.2007.015881

Publishing type：Research paper (scientific journal)  

Chlorophyll-a (Chl-a) assembled in hydrophobic domain by fatty acid with long alkyl hydrocarbon chain such as myristic acid (Myr), stearic acid (Ste) and cholic acid (Cho) modified onto nanocrystalline TiO2 electrode is prepared and the photovoltaic properties of the nanocrystalline TiO2 film by Chl-a are studied. Incident photon to current efficiency (IPCE) value at 660 nm in photocurrent action spectrum of Chl-a/Ste-TiO2, Chl-a/Myr-TiO2 and Chl-a/Cho-TiO2 electrodes are 5.0%, 4.1% and 4.1%, respectively. Thus, the IPCE is maximum using Chl-a/Ste-TiO2 electrode. From the results of photocurrent responses with light intensity of 100 mW cm-2 irradiation or monochromatic light with 660 nm, generated photocurrent increases using Chl-a/Ste-TiO2 electrode compared with the other Chl-a assembled TiO2 electrodes. These results show that the hydrophobic domain formed by stearic acid with long alkyl hydrocarbon chain is suitable for fixation of Chl-a onto TiO2 film electrodes and photovoltaic performance is improved using Chl-a onto Ste-TiO2 film electrode. © 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.electacta.2007.02.071

Publishing type：Research paper (scientific journal)  

An optical oxygen-sensing activity of anchored porphyrin derivatives on ordered porous aluminium oxide plates was studied in relevance to development of new oxygen-sensing systems. Porphyrin derivatives, 5,10,15,20-tetrakis(4- carboxylundecane-1-oxy)porphyrin (1H), 5-[4-(11-carboxylundecane-1- oxy)-10,15,20-triphenyl]porphyrin (2H), 5-(4-carboxylphenyl)-10,15, 20-triphenylporphyrin (3H), and their platinum complexes, 5,10,15,20-tetrakis(4-carboxylundecane-1-oxy)porphyrinatoplatinum(ii) (1 Pt), 5-[4-(11-carboxylundecane-1-oxy)-10,15,20-triphenyl] porphyrinatoplatinum(ii) (2Pt), 5-(4-carboxylphenyl)-10,15,20- triphenylporphyrinatoplatinum(ii) (3Pt), were synthesized and anchored by an equilibrium adsorption method on aluminium oxide plates, which were prepared by an anodic oxidation. The excitation spectra of the porphyrin-anchored layers showed a broadened and blue-shifted Soret band compared with the corresponding porphyrins in DMSO. The luminescence intensity decreased with increasing oxygen concentrations. The oxygen-sensing ability estimated from I0/I100 (I0 and I100 denote the luminescence intensity in 0 and 100% oxygen) was (1H) 9.08, (2H) 6.78, (3H) 8.71, (1Pt) 81.9, (2 Pt) 35.5, and (3Pt) 39.1, which are greater than those of corresponding porphyrin derivatives in DMSO under the measured conditions, and indicates the remarkable enhancement effect of platinum(ii). Non-linear Stern-Volmer plots were well fitted by the two component system to give the oxygen-sensitive constant (KSV1/%-1), the oxygen-insensitive constant (KSV2/%-1), and the former contribution (f1): (1H) 0.232, 3.32 × 10 -2, and 0.642; (2H) 0.141, 2.05 × 10-2, and 0.687; (3H) 0.143, 1.05 × 10-2, and 0.882; (1Pt) 17.3, 7.04 × 10-3, and 0.980; (2Pt) 10.2, 1.43 × 10-2, and 0.935; (3Pt) 16.3, 8.35 × 10-3, and 0.954. The response time for the change of the atmospheric gas from argon to oxygen was (1H) 9.4 s, (2H) 12.5 s, (3H) 9.6 s, (1Pt) 5.0 s, (2Pt) 8.9 s, and (3Pt) 4.6 s, indicating the shortening effect of platinum. The reverse effect of platinum was observed in the change from oxygen to argon: (1H) 15.5 s, (2H) 17.0 s, (3H) 20.8 s, (1 Pt) 667.4 s, (2Pt) 590.1 s, and (3Pt) 580.4 s, indicating the specific interaction of oxygen to the platinum(ii) center. © The Royal Society of Chemistry and Owner Societies.

DOI： 10.1039/b618030b

Publishing type：Research paper (scientific journal)  

Visible light and enzymatic induced synthesis of malic acid from pyruvic acid and HCO3-with malic enzyme (ME) and NADP+photoreduction by the visible light photosensitization of chlorophyll derivative, zinc chlorin-e6(Zn Chl-e6) in the presence of NADH as an electron-donating reagent was investigated. When the sample solution containing NADH, Zn Chl-e6, methylviologen (MV2+), pyruvic acid, NaHCO3, NADP+, ferredoxine-NADP+-reductase (FNR) and ME was irradiated with visible light (>390 nm), malic acid was produced. The produced malic acid was 0.65 mmol dm-3after 3 h visible light irradiation. © 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.catcom.2006.07.026

Publishing type：Research paper (scientific journal)  

Photovoltaic conversion using zinc chlorin-e6(ZnChl-e6), which is zinc chlorophyll-a derivative, and fatty acid (myristic acid or cholic acid) co-adsorbed nanocrystalline TiO2layer onto ITO glass (OTE) electrode is developed. The maximum peaks of photocurrent action spectrum of the ZnChl-e6adsorbed TiO2layer onto OTE (ZnChl-e6/TiO2) are 400, 660 and 800 nm, respectively. Especially the IPCE value at 800 nm (7.5%) is larger than that of 660 nm (6.9%). This result indicates that ZnChl-e6molecules is aggregated or formed dimer on a nanocrystalline TiO2layer onto OTE and the absorption band is shifted to near IR region. The photocurrent action spectrum of ZnChl-e6and cholic acid adsorbed TiO2layer onto OTE (ZnChl-e6-Cho/TiO2) is similar to that of the UV-vis absorption spectrum in methanol solution, and IPCE values at 400 and 660 nm (8.1%) increase and the IPCE value at 800 nm (4.1%) decreases, indicating that the aggregation of ZnChl-e6molecules on the TiO2is suppressed by cholic acid. By using ZnChl-e6-Cho/TiO2, the short-circuit photocurrent density and open-circuit photovoltage also increase compared with that of ZnChl-e6adsorbed nanocrystalline TiO2electrode. © 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.bios.2006.07.006

PubMed

Publishing type：Research paper (scientific journal)  

We evaluated the photochemical and enzymatic synthesis of methanol from formaldehyde with alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae and NAD+photoreduction by the visible-light sensitization of zinc tetraphenylporphyrin tetrasulfonate (ZnTPPS) in the presence of methylviologen (MV2+), diaphorase, and triethanolamine (TEOA). When the sample solution containing ZnTPPS, MV2+, NAD+, diaphorase, and TEOA in potassium phosphate buffer solution was irradiated, the NADH produced increased with the irradiation time. After irradiation for 180 min, the conversion yield of NAD+to NADH was about 60% under 0.1 mM NAD+condition. The methanol production also depended on the conversion yield of NAD+to NADH. After irradiation for 180 min, 0.38 μM of methanol was produced from formaldehyde (16 μM). The conversion ratio of formaldehyde to methanol was about 2.3%. This result indicates that a system for the photochemical synthesis of methanol from formaldehyde was developed with ADH and the NADH produced by the photosensitization of ZnTPPS in water media. © 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molcatb.2006.08.001

Publishing type：Research paper (scientific journal)  

Photoinduced hydrogen production with Mg chlorophyll-a (MgChl-a) from spirulina as a visible-light photosensitizer by use of three component system consisting of NADH as an electron donor, methylviologen (MV2+) as electron relay reagent and colloidal platinum as hydrogen production catalyst in cationic surfactant, alkyltrimethyl bromide with different methylene chain length (CH3(CH2)nN+(CH3)3·Br-; n = 9, 13 and 15) micellar media is investigated. Consequently, the effective MV2+photoreduction and hydrogen production system is accomplished using MgChl-a in CH3(CH2)15N+(CH3)3·Br-micellar media. © 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2005.10.077

Publishing type：Research paper (scientific journal)  

Zn chlorophyll-a derivative, Zn chlorin-e6(ZnChl-e6) and carotenoid derivative, crocetin (Cro) adsorbed onto a nanocrystalline TiO2film (ZnChl-e6-Cro/TiO2) electrode was prepared and the photovoltaic properties of ZnChl-e6-Cro/TiO2electrode were studied. Incident photon to current efficiency (IPCE) value at 640 nm in photocurrent action spectrum of ZnChl-e6-Cro/TiO2electrode was ca. 2.50%. In contrast, IPCE value at 640 nm in ZnChl-e6/TiO2electrode was ca. 1.27%. Thus, the IPCE value increases by co-adsorbed crocetin and ZnChl-e6onto TiO2film electrode. From the results of photocurrent responses with light intensity of 100 mW cm-2irradiation, generated photocurrents in the ZnChl-e6-Cro/TiO2and ZnChl-e6/TiO2electrodes are 380 and 180 μA cm-2, respectively. Photocurrent increases using ZnChl-e6-Cro/TiO2electrode compared with that of ZnChl-e6/TiO2electrode. © 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2005.11.082

Publishing type：Research paper (scientific journal)  

The fluorescence behavior of pyrene-1-butylic acid (PBA) chemisorption layer onto nano-porous anodic oxidized aluminum with a myristic acid layer was investigated and its device was applied as a fluorescence oxygen sensing material. When the ratio of [myristic acid]/[PBA] onto anodic oxidized aluminum plate increased, the fluorescence intensity due to monomer emission increased and the intensity due to excimer emission decreased. These results show that the polarity of the microenvironment around PBA molecules increased by chemisorption of myristic acid and the excimer formation between PBA molecules was suppressed by the myristic acid layer onto nano-porous anodic oxidized aluminum plate. Both of fluorescence attributed to monomer and excimer were quenched by oxygen. The l0/l100 values, where l 0 and l100 represent the detected fluorescence intensities from a substrate exposed to 100% argon and 100% oxygen, respectively, in monomer emission increased with increasing the ratio of myristic acid to PBA. In contrast, the l0/l100 values in excimer emission decreased with increasing the ratio of myristic acid to PBA. The PBA onto anodic oxidation of aluminum plates with myristic acid layer obey the modified Stern-Volmer equation and the Stern-Volmer constant, Ksv at 376 nm attributed to monomer and 461 nm attributed to excimer increased and decreased with increasing the ratio of myristic acid to PBA. Copyright © 2006 American Scientific Publishers.

DOI： 10.1166/sl.2006.013

Publishing type：Research paper (scientific journal)  

Preparation of intercalation compounds using H3PO4electrolyte solution in mesophase-pitch-based carbon fibers successfully carried out by electrolysis in less than 10 mol/dm3of its electrolyte solution. Structural changes with preparation of intercalation compounds of carbon fibers were confirmed by a peak appeared around 2θ=8° observed after electrolysis, which corresponds to an interlayer spacing of about 0.9 nm through XRD pattern (anticathode: Cu Kα). This new peak was reasonably supposed to be due to the intercalation into interspacing of carbon layers. Suitable synthesis condition of the intercalation compounds was determined to be the concentration of electrolyte of 5 mol/dm3at the electrolysis. It was also confirmed by morphology changes through SEM, that is carbon fibers, which treated low electrolyte concentration synthesized the intercalation compounds easily, and then it revealed markedly morphology changes such as fibrils. It could become exfoliation as well as them treated by other acid treatment through rapid heat-treatment. The formation of graphite oxide was suggested when the kind of intercalate was analyzed with elementary and TPD analysis. © 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jpcs.2006.01.086

Publishing type：Research paper (scientific journal)  

Photochemical and enzymatic formic acid synthesis from CO2gas system with the combination of formate dehydrogenase (FDH) from Saccharomyces cerevisiae and methylviologen (MV2+) reduction by the visible light photosensitisation of Mg chlorophyll-a (Mg Chl-a) is developed. Photochemical formic acid produced from CO2by adding FDH to the MV2+photoreduction system using photosensitisation of Mg Chl-a in the presence of NADPH as an electron donating reagent, and 56 μM of formic acid from CO2gas is produced after 4 h irradiation (1.0 M = 1.0 mol dm-3). © 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.catcom.2005.10.005

Publishing type：Research paper (scientific journal)  

Starting materials such as Ti4O7were mixed with PVA powders in various mass ratios and then heated up to different temperatures from 900°C in Ar. Fine particles of photocatalytic Ti4O7were coated by carbon, and reduced phases, such as Ti5O9were formed through interaction between Ti4O7and coated carbon. The photocatalytic activity was evaluated from the decomposition of iminoctadine triacetae (IT) in aqueous solution under visible light or UV irradiation. Commercial grades of anatase (ST-01), and commercially available Ti4O7were employed as reference materials. Under UV irradiation, the carbon-coated Ti4O7and Ti5O9were confirmed to have photocatalytic activity, though a little lower than that of anatase (ST-01). However, carbon-coated Ti4O7and Ti5O9were photoactive even under visible light, whereas anatase ST-01 was inactive. On comparison of Ti4O7and Ti5O9with and without carbon coating under irradiation of visible light, it was confirmed that Ti4O7and Ti5O9with carbon-coating had a higher photocatalytic activity than uncoated oxides. © 2006 Science & Technology Network, Inc.

Publishing type：Research paper (scientific journal)  

Biohydrogen production with the light-harvesting function of grana from spirulina by use of three-component system consisting of NADH, methylviologen (MV2+) and colloidal platinum was investigated. The decay rate of chlorophyll included in grana was suppressed by addition of NADH and little degradation was observed in 120 min irradiation. The biohydrogen production system was developed using the light-harvesting function of grana and platinum colloid in the presence of NADH and MV2+ and the amount of hydrogen produced was estimated to be 0.14μmol after 4 h irradiation. © 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2005.03.009

Publishing type：Research paper (scientific journal)  

In order to investigate photoluminescence behaviour of an ordered molecular porphyrin monolayer and its quenching properties by oxygen gas, a porphyrin with long alkyl chains, 5,10,15,20-tetrakis[4-(11-carboxylundecane-1-oxy)phenyl] porphyrin (4), was synthesized and adsorbed onto an indium-tin oxide (ITO) substrate by a chemical dipping method. Cyclic voltammetry was used to analyze the ITO electrode coated with 4. The peak current of the first oxidation was proportional to the sweep rate, and the surface coverage was estimated to be 2.3-2.5 × 10-10mol cm-2. The UV-vis spectrum of the monolayer showed a broadened Soret band, which shifted to longer wavelength. These features suggest that the porphyrin moieties of 4 are packed to form a J-type structure. The oxygen quenching ratio of the porphyrin 4 monolayer on the ITO electrode, I0/I100, was estimated to be 1.25, where I0and I100are, respectively, luminescence intensity values in 100% argon and 100% oxygen. On repeated step cycling between 100% argon and 100% oxygen atmospheres, the response times of luminescence quenching were 10 s (argon to oxygen) and 23 s (oxygen to argon). These findings suggest that a monolayer of sensing dye is applicable for oxygen sensing system without deterioration of size-accuracy of models. © 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.electacta.2005.05.030

Publishing type：Research paper (scientific journal)  

A green process for hydrogen production, coupling hydrolysis of cellulose derivative, methylcellulose (MCn) with different average molecular weights of 15 000, 21 000, 26 000, 41 000, 63 000 and 86 000, by cellulase and glucose dehydrogenase (GDH) and hydrogen production with platinum colloid as a catalyst using the visible light-harvesting function of Mg chlorophyll-a (Mg Chl-a) from Spilurina, has been developed. When the sample solution containing MCn, cellulase, nicotinamide adenine dinucleotide (NAD+), GDH, Mg Chl-a, methylviologen (MV2+, an electron carrier reagent) and platinum colloid is irradiated, continuous hydrogen production is observed with irradiation time. For all systems using MCn, the amount of hydrogen production is more than 10 μmol after 4 h irradiation. Hydrogen production is not affected by the polymerization degree of MCn. © The Royal Society of Chemistry 2005.

DOI： 10.1039/b504377h

Publishing type：Research paper (scientific journal)  

A new optical CO2sensor based on luminescence intensity changes of tetraphenylporphyrin (TPP) due to the absorption change of pH indicator dye (α-naphtholphthalein) with CO2is developed and its CO2sensing properties in pure water are investigated. The observed luminescence intensity from TPP at 650 nm increased with increasing the CO2concentration in pure water. The ratio I100/I0, where I0and I100represent the detected luminescence intensities from a layer exposed to 100% argon and 100% CO2, respectively, that we takes the sensitivity of the sensor is estimated to be 430. The response times of the sensing film are 42.6 s for switching from argon to CO2, and 88.8 s for switching from CO2to argon in pure water. The signal changes are fully reversible and no hysterisis is observed during the measurements. © 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2004.12.028

Publishing type：Research paper (scientific journal)  

A series of new fluorine-containing poly(aryl ether ketone)s (8F-PEKEK(Ar); Ar: 2-2-bis(4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane (6FBA), 2,2-bis(4-hydroxyphenyl)propane (BA), 2-(4-hydroxyphenyl)-2-(3- hydroxyphenyl)propane (3,4′-BA) or 9,9′-bis(4-hydroxyphenyl)fluorine (HF)) are synthesized and applied to the matrix of optical CO2sensor based on the overlay of the CO2induced absorbance change of pH indicator dye α-naphtholphthalein with the fluorescence of tetraphenylporphyrin (TPP) was developed. The observed luminescence intensity from TPP at 655 nm increased with increasing the CO2concentration. The ratio/100//0values of the sensing films consisting of α-naphtholphthalein in 8F-PEKEKs layer and TPP in polystyrene layer, where/0and /100represent the detected luminescence intensities from a layer exposed to 100% argon and 100% CO2, respectively, that the sensitivity of the sensor, are more than 3.6. The response and recovery times of the sensing films consisting of α-naphtholphthalein in 8F-PEKEKs layer and TPP in polystyrene layer were less than 8.6 s for switching from argon to CO2, and for switching from CO2to argon. The signal changes were fully reversible and no hysterisis was observed during the measurements. The highly sensitive and fast responsible optical CO2sensor based on fluorescence intensity changes of TPP due to the absorption change of a-naphtholphthalein in 8F-PEKEKs layer with CO2was achieved. Copyright © 2005 American Scientific Publishers.

DOI： 10.1166/sl.2005.014

Publishing type：Research paper (scientific journal)  

An optical CO2sensor based on the overlay of the CO2induced absorbance change of pH indicator dye α-naphtholphthalein in poly(isobutyl methacrylate) (polyIBM) layer with the fluorescence of tetraphenylporphyrin (TPP) in polystyrene layer is developed. The observed luminescence intensity from TPP at 655 nm increased with increasing the CO2concentration. The ratio I100/I0value of the sensing film consisting of α-naphtholphthalein in polyIBM and TPP in polystyrene layer, where I0and I100represent the detected luminescence intensities from a layer exposed to argon and CO2saturated conditions, respectively, that the sensitivity of the sensor, is estimated to be 192. The response and recovery times of the sensing film are less than 6.0 s for switching from argon to CO2, and for switching from CO2to argon. The signal changes are fully reversible and no hysterisis is observed during the measurements. The highly sensitive optical CO2sensor based on fluorescence intensity changes of TPP due to the absorption change of α-naphtholphthalein in polyIBM layer with CO2is achieved. © 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.talanta.2004.12.058

Publishing type：Research paper (scientific journal)  

A biohydrogen production system, has been developed that couples sucrose hydrolysis by invertase and glucose dehydrogenase (GDH) and hydrogen production with a platinum colloid as a catalyst. The system uses the visible light-harvesting function of artificial Zn chlorophyll-a (Zn Chl-a), prepared from Mg Chl-a (obtained from Spilurina). When a sample solution containing sucrose, invertase, nicotinamide adenine dinucreotide (NAD+), Zn Chl-a, methylviologen (MV2+, an electron carrier), and platinum colloid was irradiated, continuous hydrogen production was observed with the irradiation time. The amount of hydrogen production was about 10.5 μmol after 4 h of irradiation under the optimum condition. © 2005 The Chemical Society of Japan.

DOI： 10.1246/bcsj.78.622

Publishing type：Research paper (scientific journal)  

An optical CO2sensor based on the overlay of the CO2induced absorbance change of pH indicator dye α-naphtholphthalein in poly(trimethylsiliypropyne) (poly(TMSP))layer with the fluorescence of tetraphenylporphyrin (TPP) in polystyrene layer is developed. The observed luminescence intensity from TPP at 655 nm increased with increasing the CO2concentration. The ratio I100/I0value of the sensing film, where I0and I100represent the detected luminescence intensities from a layer exposed to 100% argon and 100% CO2, respectively, that the sensitivity of the sensor, is estimated to be 10.3. The response and recovery times of the sensing film are less than 3.0 s for switching from argon to CO2, and for switching from CO2to argon. The signal changes are fully reversible and no hysteresis is observed during the measurements. The highly sensitive and fast responsible optical CO2sensor based on fluorescence intensity changes of TPP due to the absorption change of α-naphtholphthalein with CO2is achieved using poly(TMSP) film. © 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.reactfunctpolym.2005.02.003

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Participation form：Corresponding Author

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

A Biohydrogen production system, coupling D-maltose hydrolysis by glucoamylase and glucose dehydrogenase (GDH) and hydrogen production with platinum nanoparticle colloid catalyst using the photosensitisation based on the visible light harvesting of Mg chlorophyll-a (Mg Chl-a), was developed. Hydrogen gas was continuously produced when the reaction mixture containing D-maltose, glucoamylase, GDH, nicotinamide adenine dinucreotide (NAD +), Mg Chl-a, methylviologen (MV2+) and platinum nanoparticle colloid was irradiated by visible light. The amount of hydrogen production was estimated to be 5.0 μmol after 4 h irradiation and the yield of conversion of D-maltose to hydrogen gas was about 1.8%. The quantum yield was 3.1%.

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Chloroplast obtained from green plant is assembled onto TiO2 layer electrode and photovoltaic conversion system using Chloroplast assembled electrode is developed. The photovoltaic conversion system consists of Chloroplast assembled electrode as a working electrode, platinum-coated ITO electrode as a counter electrode and tetrabutylammonium hexafluorophospate - water in acetonitrile as an electrolyte. When the Chloroplast assembled electrode is irradiated with visible light using tetrabutylammonium hexafluorophospate - water in acetonitrile as an electrolyte, the photocurrent is observed.

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

In this study, Mg chlorophyll adsorbed on TiO2 film electrode which is model of natural LH protein-chlorophyll pigment is prepared and photovoltaic conversion system using the light-harvesting function of Mg chlorophyll adsorbed on TiO2 film is constructed. The purpose of this study is the preparation of chlorophyll assembly on electrode mimicking natural LH-protein and its application for photovoltaic conversion system. Photocurrent was increased under irradiation or monochromatic light of 660nm and the peak of action spectra was appeared around 400 and 660 nm.This result indicates the observed photocurrent induced by chlorophyll, especially the light of around 400 and 660 nm attributed to chlorophyll was used efficiently.

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Photosynthesis protein consists of chlorophyll and carotenoid such as β-carotein. Crotenoids play an important role of harvesting the UV light and energy transfer to the chlorophyll moiety. In this work, chlorophyll derivative, Zn chlorin-e6 (ZnChl-e6) and carotenoid derivative, crocetin (Cro) adsorbed onto a nanocrystalline TiO2 film (ZnChl-e6-Cro/TiO2) electrode was prepared as an artificial photosynthesis protein and the photovoltaic properties of ZnChl-e6-Cro/TiO2 electrode were studied.

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

To elucidate the role of cardiolipin (CL) on redox behavior of cytochrome c (cyt c (III)), the photoreduction of cyt c using the photosensitization of zinc tetraphenylporphyrin in presence of triethanolamine (TEOA) as a sacrificial electron-donating reagent in various lipid media were studied. The initial rate of cyt c (III) photoreduction in various lipid, CL, L-α-phosphatidic acid (PA), dimethyldipalmitoylammonium bromide (DMPA) and Triton X-100 media were 1.0, 0.73, 0.80 and 0.67 μmol dm-3min-1, respectively. The cyt c (III) photoreduction rate slightly increased by the addition of CL. © 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jphotobiol.2004.12.004

PubMed

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

A Zn chlorophyll-a derivative, Zn chlorin-e6(ZnChl-e6), adsorbed onto a nanocrystalline TiO2film (ZnChl-e6/TiO2) electrode was prepared, and the photovoltaic properties of the ZnChl-e6/TiO2electrode were studied. The absorption peaks of ZnChl-e6/TiO2observed at 420, 654, and 795 nm were attributed to the ZnChl-e6molecules aggregating onto TiO2film. The fluorescence attributed to the ZnChl-e6monomer and aggregate was observed at 710 and 820 nm, respectively, and the fluorescence in both cases was quenched by TiO2particles. The maximum of the incident photon-to-current conversion efficiency (IPCE) value in the photocurrent action spectrum was 800 nm, and the IPCE value was 7.0%. ZnChl-e6molecules formed aggregates on a nanocrystalline TiO2film electrode. From the photocurrent-photovoltage characteristics of the ZnChl-e6/TiO2electrode irradiated with 100 mW cm-2, the short-circuit photocurrent (ISC) was found to be 0.19 mA cm-2and the open-circuit photovoltage (VOC) was found to be 375 mV. The maximum power was estimated to be 28.7 μW cm-2, and the fill factor (FF) was estimated to be 40.1%. A near-IR light induced photovoltaic conversion system using a ZnChl-e6aggregate formed onto a nanocrystalline TiO2film electrode was achieved. © 2005 American Chemical Society.

DOI： 10.1021/la047579p

PubMed

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Zn chlorophyll-a was prepareted from Mg chlorophyll-a from spirulina and the optical properties of the ground state and the photoexited state of Zn chlorophyll-a in aqueous surfactant micellar media were studied using UV-vis absorption, fluorescence emission spectra, electrochemical and fluorescence lifetime measurements. In comparison of the UV-vis absorption and fluorescence emission spectra of Zn chlorophyll-a and Mg chlorophyll-a, the blue-shift in the absorption bands and emission peak of Zn chlorophyll-a was observed. The energies of the first excited singlet state of Zn chlorophyll-a was 1.87eV. The first oxidation and reduction potentials of the photoexcited singlet state of Zn chlorophyll-a were -0.67 and 0.60V, respectively. Fluorescence lifetime of Zn chlorophyll-a was 9.0 ns in CTAB micellar solution. The fluorescence lifetime of Zn chlorophyll-a is shorter than that of Mg chlorophyll-a (9.8 ns). The photositability of Zn chlorophyll-a was superior to that of Mg chlorophyll-a in various pH conditions. © Springer 2005.

DOI： 10.1007/s10534-004-5770-z

PubMed

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

A hydrogen production system, coupling d-maltose hydrolysis by glucoamylase and glucose dehydrogenase (GDH) and hydrogen production with Pt colloid catalyst using light-induced photosensitization of Mg chlorophyll a (Mg Chl-a), was developed. Hydrogen gas was continuously produced when the reaction mixture containing d-maltose, glucoamylase, GDH, nicotinamide adenine dinucreotide (NAD+), Mg Chl-a, methylviologen (MV2+) and Pt colloid was irradiated by visible light. The amount of hydrogen production was estimated to be 5.0 μmol after 4 h irradiation and the yield of conversion of d-maltose to hydrogen gas was about 1.8%. The quantum yield was 3.1%. © 2005, The Japan Petroleum Institute. All rights reserved.

DOI： 10.1627/jpi.48.29

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Mg chlorophyll-a (MgChl-a) with imidazole-4-acetic acid (Im) as the axial ligand (MgChl-a-Im), adsorbed on a nanocrystalline TiO2film electrode, was prepared. Further, the photoelectrical properties of a solar cell using visible-light sensitisation of the nanocrystalline TiO2film through an axial Im ligand of MgChl-a were investigated.

DOI： 10.1246/bcsj.78.132

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Photochemical synthesis of malic acid was investigated by using pyruvic acid and CO2with a malic enzyme (ME). NADP+photoreduction was conducted by the visible light photosensitization of zinc chlorin-e6(Zn Chl-e6) in the presence of NADH as an electron-donating reagent. Irradiation of a solution containing NADH, Zn Chl-e6, methylviologen (MV2+), pyruvic acid, NaHCO3, NADP+, ferredoxine-NADP-reductase (FNR) and ME with visible light resulted in malic acid synthesis. The amount of malic acid was 0.65 mmol dm-3after 3 h irradiation.

DOI： 10.1295/koron.62.190

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property_type：Patent 

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