Characterization of the Photophysical Behavior of DFHBI Derivatives: Fluorogenic Molecules that Illuminate the Spinach RNA Aptamer.
Characterization of the Photophysical Behavior of DFHBI Derivatives: Fluorogenic Molecules that Illuminate the Spinach RNA Aptamer.
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DOI：
10.1021/acs.jpcb.8b11166
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发表时间：
2019-02
期刊：
影响因子：
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通讯作者：
K. Santra;Ivan M Geraskin;M. Nilsen-Hamilton;G. Kraus;J. Petrich
中科院分区：
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作者：
K. Santra;Ivan M Geraskin;M. Nilsen-Hamilton;G. Kraus;J. Petrich
(Z)-5-(3，5-Difluoro-4-hydroxybenzylidene)-2，3-dimethyl-3，5-dihydro-4 H-咪唑-4-酮(DFHBI)及其类似物是与菠菜适配子(一种小的核糖核酸分子)结合的荧光分子，该分子被选中用于核糖核酸成像。它们在液体溶剂中的荧光极弱。人们曾假设光异构化是一种非常有效的非辐射失活过程。我们发现，与其他研究结果一致，如果异构化被阻止，荧光信号显著增强。此外，我们对DFHBI及其衍生物，特别是(Z)-5-(3，5-difluoro-4-hydroxybenzylidene)-2-methyl-3-((perfluorophenyl)methyl)-3，5-dihydro-4 H-咪唑-4-酮，PFP-DFHBI)在各种溶剂环境中的光物理行为进行了全面的表征。用不同的混合溶剂进行了溶剂依赖性研究。结果表明，溶剂与酚羟基的氢键或强相互作用通过不同程度的稳定化以及中性离子和阴离子物种在基态和激发态之间的转化，改变了420-460 nm附近的吸收带和430-500 nm附近的发射性质。用甲氧基取代的分子((Z)-5-(4-methoxybenzylidene)-2，3-dimethyl-3，5-dihydro-4 H-咪唑-4-酮))证实了这些结果，在甲醇存在下没有420-460 nm的谱带，并且与在乙腈和二氯甲烷等非相互作用的溶剂中的光谱相似。因此，除了光异构化作为激发态失活的非辐射过程的主要作用外，DFHBI型分子的荧光非常敏感地依赖于介质的pH以及特定于溶剂的相互作用，如氢键能力和极性。
( Z)-5-(3,5-Difluoro-4-hydroxybenzylidene)-2,3-dimethyl-3,5-dihydro-4 H-imidazol-4-one (DFHBI) and its analogues are fluorogenic molecules that bind the Spinach aptamer (a small RNA molecule), which was selected for imaging RNA. They are extremely weakly fluorescent in liquid solvents. It had been hypothesized that photoisomerization is a very efficient nonradiative process of deactivation. We show, consistent with the results of other studies, that if the isomerization is impeded, the fluorescence signal is enhanced significantly. In addition, we provide a thorough characterization of the photophysical behavior of DFHBI and its derivatives, notably that of ( Z)-5-(3,5-difluoro-4-hydroxybenzylidene)-2-methyl-3-((perfluorophenyl)methyl)-3,5-dihydro-4 H-imidazol-4-one (PFP-DFHBI) in various solvent environments. Solvent-dependent studies were performed with various mixtures of solvents. The results suggest that hydrogen bonding or strong interactions of the solvents with the phenolic-OH group change the absorption band near 420-460 nm and the nature of emission near 430 and 500 nm through various degrees of stabilization and the transformation between the neutral and the anionic species at both ground and excited states. These observations are confirmed by using a methoxy-substituted molecule (( Z)-5-(4-methoxybenzylidene)-2,3-dimethyl-3,5-dihydro-4 H-imidazol-4-one), where the 420-460 nm band is absent in the presence of methanol and the spectra are similar to those of PFP-DFHBI in noninteracting solvents, such as acetonitrile and dichloromethane. Thus, in addition to the major role of photoisomerization as a nonradiative process of deactivation of the excited state, the fluorescence of DFHBI-type molecules is very sensitively dependent upon the pH of the medium as well as upon solvent-specific interactions, such as hydrogen-bonding ability and polarity.