Hori Alto, Matsumoto Atsushi, Ikenouchi Junichi, Konishi Gen-Ichi
Department of Chemical Science and Engineering, Institute of Science Tokyo, Meguro-ku, Tokyo 152-8552, Japan.
Department of Biochemistry, Kyushu University Faculty of Medical Science, Higashi-ku, Fukuoka 812-8582, Japan.
J Am Chem Soc. 2025 Mar 19;147(11):9953-9961. doi: 10.1021/jacs.5c01173. Epub 2025 Mar 5.
Fluorescence thermometry has emerged as a significant area of research in the field of remote temperature sensing with high accuracy. However, the development of noninvasive and reliable small organic fluorescence thermometers (FTs) remains challenging. In this study, we developed a high-sensitivity, high-resolution small organic ratiometric FT with a solvatochromic dye and analyzed its temperature response mechanism. π-Extended fluorene-based D-π-A-type small solvatochromic dyes (, , and ) were synthesized and characterized. A significant solvatochromic shift of >200 nm was observed between -hexane and tetrahydrofuran (THF) for both and , with emission in THF reaching the red region (701 nm, 828 nm). This substantial solvatochromic shift was accompanied by a concurrent decrease in the fluorescence quantum yield and is attributable to accelerated internal conversion. The fluorescence spectra of in THF and in diethyl ether exhibited blue shifts and increased fluorescence intensities with a decrease in polarity at increased temperatures. Our observations revealed an absolute sensitivity of 21%/°C and a relative sensitivity of 3.0%/°C at the maximum. These results represent the highest sensitivity and resolution reported for single fluorophore small organic ratiometric FTs dispersed in solution. The positive temperature coefficient of the fluorescence intensity was attributed to control of the nonradiative decay pathway by solvatochromism. The temperature responsiveness of could be detected in living HeLa cells by ratiometric confocal microscopy. Using the proposed strategy to develop FTs, we plan to build a library of FTs that will cover various environments of interest in both simple and complex systems.
荧光测温法已成为高精度远程温度传感领域的一个重要研究方向。然而，开发无创且可靠的小型有机荧光温度计（FTs）仍然具有挑战性。在本研究中，我们开发了一种基于溶剂化显色染料的高灵敏度、高分辨率小型有机比率型FT，并分析了其温度响应机制。合成并表征了基于π-扩展芴的D-π-A型小型溶剂化显色染料（、和）。对于和，在正己烷和四氢呋喃（THF）之间观察到大于200 nm的显著溶剂化显色位移，THF中的发射波长达到红色区域（701 nm，828 nm）。这种显著的溶剂化显色位移伴随着荧光量子产率的同时降低，这归因于加速的内转换。在THF中的荧光光谱和在乙醚中的荧光光谱随着温度升高极性降低而出现蓝移并增加荧光强度。我们的观察结果显示，最大绝对灵敏度为21%/°C，相对灵敏度为3.0%/°C。这些结果代表了分散在溶液中的单荧光团小型有机比率型FTs所报道的最高灵敏度和分辨率。荧光强度的正温度系数归因于溶剂化显色对非辐射衰变途径的控制。通过比率共聚焦显微镜可以在活的HeLa细胞中检测的温度响应性。利用所提出的策略开发FTs，我们计划建立一个FTs库，该库将涵盖简单和复杂系统中各种感兴趣的环境。
