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Excited-state dynamics of mononucleotides and DNA strands in a deep eutectic solvent
Faraday Discussions ( IF 3.3 ) Pub Date : 2017-11-06 , DOI: 10.1039/c7fd00205j Yuyuan Zhang 1, 2, 3, 4 , Kimberly de La Harpe 4, 5, 6, 7 , Mahesh Hariharan 8, 9, 10, 11 , Bern Kohler 1, 2, 3, 4
Faraday Discussions ( IF 3.3 ) Pub Date : 2017-11-06 , DOI: 10.1039/c7fd00205j Yuyuan Zhang 1, 2, 3, 4 , Kimberly de La Harpe 4, 5, 6, 7 , Mahesh Hariharan 8, 9, 10, 11 , Bern Kohler 1, 2, 3, 4
Affiliation
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The photophysics of several mono- and oligonucleotides were investigated in a deep eutectic solvent for the first time. The solvent glyceline, prepared as a 1 : 2 mole ratio mixture of choline chloride and glycerol, was used to study excited-state deactivation in a non-aqueous solvent by the use of steady-state and time-resolved spectroscopy. DNA strands in glyceline retain the secondary structures that are present in aqueous solution to some degree, thus enabling a study of the effects of solvent properties on the excited states of stacked bases and stacked base pairs. The excited-state lifetime of the mononucleotide 5′-AMP in glyceline is 630 fs, or twice as long as in aqueous solution. Even slower relaxation is seen for 5′-TMP in glyceline, and a possible triplet state with a lifetime greater than 3 ns is observed. Circular dichroism spectra show that the single strand (dA)18 and the duplex d(AT)9·d(AT)9 adopt similar structures in glyceline and in aqueous solution. Despite having similar conformations in both solvents, femtosecond transient absorption experiments reveal striking changes in the dynamics. Excited-state decay and vibrational cooling generally take place more slowly in glyceline than in water. Additionally, the fraction of long-lived excited states in both oligonucleotide systems is lower in glyceline than in aqueous solution. For a DNA duplex, water is suggested to favor decay pathways involving intrastrand charge separation, while the deep eutectic solvent favors interstrand deactivation channels involving neutral species. Slower solvation dynamics in the viscous deep eutectic solvent may also play a role. These results demonstrate that the dynamics of excitations in stacked bases and stacked base pairs depend not only on conformation, but are also highly sensitive to the solvent.
中文翻译：
在低共熔溶剂中单核苷酸和DNA链的激发态动力学
首次在深共熔溶剂中研究了几种单核苷酸和寡核苷酸的光物理性质。使用氯化胆碱和甘油的摩尔比为1：2的混合物制备的溶剂甘油，通过使用稳态和时间分辨光谱法研究非水溶剂中的激发态失活。甘氨酸中的DNA链在某种程度上保留了水溶液中存在的二级结构，因此能够研究溶剂性质对堆叠碱基和堆叠碱基对的激发态的影响。甘氨酸中单核苷酸5'-AMP的激发态寿命为630 fs，或水溶液中的两倍。对于甘氨酸中的5'-TMP，观察到甚至更慢的弛豫，并且观察到可能的三线态，其寿命大于3 ns。18和双工d（AT） 9 ·d（AT） 9在甘氨酸和水溶液中采用相似的结构。飞秒瞬态吸收实验尽管在两种溶剂中具有相似的构象，但它们揭示了动力学方面的惊人变化。兴奋态衰变和振动冷却通常在甘氨酸中发生的速度要比在水中发生的速度慢。另外，在两个寡核苷酸系统中，甘氨酸中的长寿命激发态分数低于水溶液中的分数。对于DNA双链体，建议使用水促进涉及链内电荷分离的衰变途径，而深共熔溶剂则促进涉及中性物质的链间失活通道。粘性深共晶溶剂中较慢的溶剂化动力学也可能起作用。
更新日期：2018-04-17
中文翻译：
在低共熔溶剂中单核苷酸和DNA链的激发态动力学
首次在深共熔溶剂中研究了几种单核苷酸和寡核苷酸的光物理性质。使用氯化胆碱和甘油的摩尔比为1：2的混合物制备的溶剂甘油，通过使用稳态和时间分辨光谱法研究非水溶剂中的激发态失活。甘氨酸中的DNA链在某种程度上保留了水溶液中存在的二级结构，因此能够研究溶剂性质对堆叠碱基和堆叠碱基对的激发态的影响。甘氨酸中单核苷酸5'-AMP的激发态寿命为630 fs，或水溶液中的两倍。对于甘氨酸中的5'-TMP，观察到甚至更慢的弛豫，并且观察到可能的三线态，其寿命大于3 ns。18和双工d（AT） 9 ·d（AT） 9在甘氨酸和水溶液中采用相似的结构。飞秒瞬态吸收实验尽管在两种溶剂中具有相似的构象，但它们揭示了动力学方面的惊人变化。兴奋态衰变和振动冷却通常在甘氨酸中发生的速度要比在水中发生的速度慢。另外，在两个寡核苷酸系统中，甘氨酸中的长寿命激发态分数低于水溶液中的分数。对于DNA双链体，建议使用水促进涉及链内电荷分离的衰变途径，而深共熔溶剂则促进涉及中性物质的链间失活通道。粘性深共晶溶剂中较慢的溶剂化动力学也可能起作用。
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