Development of high-sensitivity time-resolved CD measuring system for elucidation of functional biopolymers dynamics

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18992
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 35:Polymers, organic materials, and related fields
• Research Institution: Tohoku University
• Principal Investigator: WADA Takehiko 東北大学, 多元物質科学研究所, 教授 (20220957)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: CDスペクトル / 楕円偏光 / 方位角制御 / 円偏光二色性 / 高感度測定 / 三重項 / 過渡吸収 / 高時間分解

Outline of Final Research Achievements

Circular dichroism (CD) spectroscopy is widely used to detect structural changes in chiral molecular systems. However, the time resolution of current CD spectrometers is limited to m-sec order because of the utilization of the PEM. To observe more fast events of chiral molecules, it has been desired to develop a novel CD measurement system that can achieve both high sensitivity and high temporal resolution of micro-sec order.
In this study, we have developed a CD measurement system with high sensitivity and time resolution by utilizing a new detection method using elliptically polarized light, which was proposed by our collaborator Assoc. Prof. Yasuyuki Araki, and demonstrated that the high sensitivity and high time-resolution observation method based on azimuthal change works effectively. We also have demonstrated that the transient CD measurement method developed in this study can measure the CD spectra of excited triplet states of organic molecules in solution at room temperature.

Free Research Field

有機光化学、生体機能関連化学、核酸化学

Academic Significance and Societal Importance of the Research Achievements

左右の円偏光吸収の差異であるCDシグナルは、シグナル強度が小さいため高感度測定が困難である事も広く知られ、SMを用いることで本課題を解決しているが、時間分解能はミリ秒程度が上限である。このため高感度と高時間分解能を両立可能な新規CD測定原理の開発が待望されてきた。本研究では荒木准教授が提案した新規楕円偏光制御法に基づく高感度CD検出装置の構築に取り組み、方位角変化に基づく高感度・高時間分解観測法が有効に機能することを実証した。さらに本研究で構築した装置により、室温・溶液中で有機分子の励起三重項状態のCDスペクトルを測定可能であることを実証し、その波及効果は極めて大きいと評価されている。