| 研究課題/領域番号 |
17K01943
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| 研究機関 | 東京工業大学 |
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研究代表者 |
ママジャノフ イリーナ 東京工業大学, 地球生命研究所, 特任教授 (80776261)
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| 研究期間 (年度) |
2017-04-01 – 2020-03-31
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| キーワード | hyperbranched polyesters / biomimetic catalysts |
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| 研究実績の概要 |
The project is focused on the study of hyperbranched polyesters (HBPE) and later polyamides as enzyme mimics and their role in chemical evolution. Research achievements include: 1) One publication partially describing results of this project; 2) One invited and one contributing oral presentation at international conferences; 3) Two manuscripts currently in preparation describing the following sub-projects:
a) Selection in HBPE synthesis in wet/dry cycling. Uncontrolled synthesis of the citric acid/glycerol HBPs yields mixtures of linear and branched polymer. Since HBP are less prone to hydrolysis, successive wet/dry cycling synthesis should enrich the mixture in HBP. This year we have developed methods for the cycling, studied hydrolysis and synthesis rates of the polymer to establish best temperatures and periods for the wet/drying. We have further ran the wet/dry cycling experiment to find that this method creates longer and more soluble polymers compared to the continuous drying methods. The resulting systems so far have been analyzed by size-exclusion chromatography and nuclear magnetic resonance.
b) Development of methyl sulfide/HBPE nanocomposite catalysts. This project is an opportunity to research the chemical evolution of ferredoxin-type enzymes, iron sulfur proteins that mediate proton transfer in a range of metabolic reactions. We have development a facile method of a metal sulfide/HBP nanoparticle synthesis and assayed the catalytic potential of the composite towards redox reactions.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
The positive aspects of the project include:
1) The hypotheses described in the proposal have proven to be correct. For the HBPE selection project through wet/dry cycling, we have conducted a number of preparatory analyses, such as measurement of polymer synthesis and hydrolysis rates. The analyses were necessary to setup the best temperatures and durations of the wetting and drying periods to achieve the selection. 2) The planned experiments proceed as expected once initial setup time and funds have been invested. 3) Based on the initial results new improvements to the proposed protocols have been implemented.
The challenges include difficulties in the analyses of the complex polymeric mixtures; analytical protocol development took more time than initially expected: 1) Size exclusion chromatographic method required further development. Our original intention was to use water based technique, however the resulting polymers tended to cluster in water solution rendering such analysis impossible. We have since developed a protocol that uses tetrahydrofuran and methanol. The development required additional time since finding a solvent system suitable for the chromatographic analysis and capable of dissolving the polymers of interest has proven challenging. 2)The microscopic analysis of the metal sulfide nanocomposites has required a lot of trial an error. Each such analysis is time consuming, selection of the optimal combination of a proper technique, sample concentration and modification, substrate grid etc required multiple analyses.
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| 今後の研究の推進方策 |
1) Selection in HBPE synthesis in wet/dry cycling. Some final analyses required to finish this part of the project.
2) Develop the functional measurements for the analyses of the HBPE. The chromatographic and spectroscopic analyses of the mixed polymers have proven challenging, however the ultimate goal of the project is to understand the possible role and the function of the HBPE in the chemical evolution. The functional measurement protocol will allow to probe for the polymer function directly. The protocol will include the ability of the HBPE mixtures prepared under different conditions to absorb metal ions and small organic molecules; Kemp elimination assay, that will probe the formation of hydrophobic pockets in polymeric structures; change behavior when exposed to different pH/temperature conditions or UV irradiation.
3) Explore the utility of metal-sulfide/HBPE nanocomposite materials. The initial experiments will focus on the photocatalytic activities of ZnS particles. The assay will involve the measurement of the rate of photobleaching of Eosin B under UV irradiation in the presence of different ZnS/HPBE formulations.
4) Explore the utility of metal-sulfide/HBPE nanocomposite materials in the context of chemical evolution. S. Martin et. al have previously shown that bulk ZnS can photo catalyze certain steps of the citric acid cycle. Given the high surface area of the ZnS/HBPE, we expect the nanocomposite material to serve as much better catalyst. Furthermore, we will explore the FeS/HBPE materials that most closely relate to ferredoxin-type enzymes.
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