Contrast Mechanisms of Solution-Dispersed Graphene Compounds in Twilight Fluorescence Microscopy
Contrast Mechanisms of Solution-Dispersed Graphene Compounds in Twilight Fluorescence Microscopy
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DOI：
10.1021/acs.langmuir.9b01349
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发表时间：
2019-08-13
期刊：
影响因子：
3.9
通讯作者：
Sano, Masahito
中科院分区：
文献类型：
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作者：
Ishikawa, Yu-uki;Watanabe, Yu-uto;Sano, Masahito
微光荧光显微镜是一种新开发的技术，能够对分散在液体中的单层石墨烯化合物进行成像。将与高浓度染料混合的石墨烯溶液放置在玻璃板上，并由激发光束以在全内反射角周围具有有限宽度的入射角照射。渐逝场和微弱的折射光束在离开玻璃表面时都呈指数衰减。由这两个光束激发的染料荧光用作照明。基于吸收和Forster共振能量转移（FRET），提出了石墨烯化合物暗对比度的简化理论，假设（1）FRET具有尖锐的截止距离，（2）FRET与层数无关，（3）Dexter电子转移可以忽略不计。还原氧化石墨烯多层膜的对比度，其层的高度已被确定由原子力显微镜，在各种染料浓度下的简化理论显示出良好的一致性。FRET的截止距离被发现是远远短于预期的石墨烯和类似的两个小分子之间的距离。这种短的截止距离是假设有效的主要原因。
Twilight fluorescence microscopy is a newly developed technique that is capable of imaging a single-layer graphene compound dispersed in a liquid. A graphene solution mixed with a highly concentrated dye is placed on a glass plate and is irradiated by the excitation beam with an incident angle that has a finite width around the total internal reflection angle. Both the evanescence field and the faint refracted beam decay exponentially as they travel from the glass surface. The dye fluorescence excited by both beams is used as illumination. A simplified theory for dark contrast of graphene compounds is developed based on absorption and Forster resonance energy transfer (FRET), assuming that (1) FRET has a sharp cutoff distance, (2) FRET is independent of the number of layers, and (3) Dexter electron transfer is negligible. The contrast of a reduced graphene oxide multilayer, whose layer heights have been determined by atomic force microscopy, shows good agreement with the simplified theory under various dye concentrations. The FRET cutoff distance is found to be much shorter than one expected for graphene and similar to the distance between two small molecules. This short cutoff distance is the main reason for the assumption to be valid.