| 研究課題/領域番号 |
22KF0095
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| 補助金の研究課題番号 |
22F22729 (2022)
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| 研究種目 |
特別研究員奨励費
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| 配分区分 | 基金 (2023)
補助金 (2022) |
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| 応募区分 | 外国 |
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| 審査区分 |
小区分28040:ナノバイオサイエンス関連
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| 研究機関 | 東京大学 |
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研究代表者 |
坂田 利弥 東京大学, 大学院工学系研究科(工学部), 准教授 (70399400)
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| 研究分担者 |
TSENG ALEX 東京大学, 大学院工学系研究科(工学部), 外国人特別研究員
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| 研究期間 (年度) |
2023-03-08 – 2024-03-31
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| 研究課題ステータス |
交付 (2023年度)
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| 配分額 *注記 |
2,300千円 (直接経費: 2,300千円)
2023年度: 1,100千円 (直接経費: 1,100千円)
2022年度: 1,200千円 (直接経費: 1,200千円)
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| キーワード | electrochemical sensing / PEDOT |
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| 研究開始時の研究の概要 |
Composite hydrogels of conductive PEDOT:PSS and modified polyacrylamides (PAAm) are promising materials for soft bioelectronics. This is because the semiconductivity of PEDOT can be preserved while designing structural and smart functions via rational selection of monomers. Therefore, we will investigate monomer compositions that optimize and combine conductance switching with chemical binding of biomolecules for sensing application in this research.
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| 研究実績の概要 |
Using UV-Vis-NIR spectroelectrochemistry, we studied the interaction of PEDOT during redox cycling of quinones from bound catechol functional groups in a composite polymer. Whereas PEDOT absorbance band shifts from visible (550 nm) to IR (>900nm) wavelengths during oxidation and reduction, respectively, quinone bands shift from visible (400 nm) to UV (280 nm). Thus, the oxidation state of redox active components and their relative proportions can be followed in-situ. Repeated cycling in physiological buffer conditions found an unexpected accumulation of oxidized PEDOT and reduced catechol, suggesting the formation of a charge-transfer complex between the two species.
Using flexible polyimide substrates, we successfully fabricated devices with suspended channels. Access to electrolyte from top and bottom sides of the hydrogel reduced the effective thickness by half resulting in improved mass transport. Accordingly, the cut-off frequency in the response of a hydrogel transistor amplifier was doubled and the rate of electrocatalyzed oxygen reduction reaction was improved. This new device structure facilitates the use of AC impedance spectroscopy to control the kinetics involved in the evolution of an electrochemical sensing signal.
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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
In FY2022, we planned for two mail goals: first, to incorporate optical absorbance spectroscopy in our experiments; and second, to develop a new device structure using suspended hydrogel channels. Both goals have been achieved.
Using UV-Vis-NIR spectroelectrochemistry, we studied the interaction of PEDOT during redox cycling of quinones from bound catechol functional groups in a composite polymer. Whereas PEDOT absorbance band shifts from visible (550 nm) to IR (>900nm) wavelengths during oxidation and reduction, respectively, quinone bands shift from visible (400 nm) to UV (280 nm). Thus, the oxidation state of redox active components and their relative proportions can be followed in-situ. Repeated cycling in physiological buffer conditions found an unexpected accumulation of oxidized PEDOT and reduced catechol, suggesting the formation of a charge-transfer complex between the two species.
Using flexible polyimide substrates, we successfully fabricated devices with suspended channels. Access to electrolyte from top and bottom sides of the hydrogel reduced the effective thickness by half resulting in improved mass transport. Accordingly, the cut-off frequency in the response of a hydrogel transistor amplifier was doubled and the rate of electrocatalyzed oxygen reduction reaction was improved. This new device structure facilitates the use of AC impedance spectroscopy to control the kinetics involved in the evolution of an electrochemical sensing signal.
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| 今後の研究の推進方策 |
In FY2023, we will proceed to study the effect of monomer composition on the structural, electrochemical, and electro-mechanical properties of the double network hydrogel. Using co-polymers of polyacrylamide, we aim to incorporate functional groups with cationic (e.g., amine), zwitterionic (e.g., sulfobetaine, carboxybetaine), and redox active (e.g., catechol, aminoxyl) properties. Because oxidized PEDOT exists as a complex with anions in aqueous conditions, we expect that altering the electrostatic environment within the hydrogel will mediate charge screening and lead to changes in electronic transport and electro-mechanical behaviour. Additionally, bound redox centers can serve as indicators of electrochemical state, with read-outs by multiple means as previously discussed.
Currently, we are constructing experimental apparatus to support lyophilization (i.e., freeze-drying) of hydrogels. Although this is primarily intended to enable accurate micro-structure characterization of physically cross-linked hydrogels, additional capability for low-temperature processing may enable other techniques such as freeze-casting or pore-size modification to further tune the mechanical and mass transport properties of these materials.
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