Fluorescence on -off switching by single wavelength irradiation: Development of highly durable nanoparticles and application to single particle fluorescence measurement

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18934
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 32:Physical chemistry, functional solid state chemistry, and related fields
• Research Institution: Osaka University
• Principal Investigator: Miyasaka Hiroshi 大阪大学, 大学院基礎工学研究科, 教授 (40182000)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: 超解像蛍光観測 / 蛍光スイッチング / 会合体生成 / ナノ粒子 / １波長制御

Outline of Final Research Achievements

It was found that nanoparticles composed of more than 10000 molecules enabling the controlled fluorescence ON-OFF states exhibit fluorescence ON-OFF behaviors as a whole particle. Because these nanoparticles allows the fluorescence measurement with weak excitation light intensity due to an increase in the light absorption probability, they enable long-time measurement when they are applied to the super-resolution fluorescence microscopy. In this study, detailed measurements and analyses were carried out with the aim of elucidating this ON-OFF mechanism. As a result, when ON-state molecules are produced adjacent to each other by a photoreaction, a significantly weakly fluorescent aggregate is formed, which captures excitation energy, leading to the fluorescent OFF state of the whole particle. On the other hand, the fluorescence of the whole particle was turned on when the ring-opening reaction took place in the aggregates resulting in the independent ON state.

Free Research Field

光機能材料

Academic Significance and Societal Importance of the Research Achievements

単一分子の蛍光像の重心を数nmの分解能で決定し超解像を得る手法は、静的画像のみならず単一分子の動的拡散挙動測定も可能とする。この方法では蛍光ONとOFF状態をスイッチできる分子が重要な役割を果たす。しかし測定には非常に強い励起光強度が必用で、色素の光劣化も迅速に進行するため、長時間、広空間域の知見を得ることは困難であった。本研究では、近年我々が見出した可視単一波長照射下で、全体として蛍光ON－OFF挙動を示すナノ粒子を対象に、その構解明を行った。得られた知見から、非常に弱い照射光強度で測定可能かつ長時間測定を可能とする新たな蛍光ON-OFF可能なナノ粒子の合理的設計が可能となった。