Fluorescence of Natural DNA: From the Femtosecond to the Nanosecond Time Scales
Fluorescence of Natural DNA: From the Femtosecond to the Nanosecond Time Scales
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DOI：
10.1021/ja102800r
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发表时间：
2010-09-01
影响因子：
15
通讯作者：
Markovitsi, Dimitra
中科院分区：
文献类型：
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作者：
Vaya, Ignacio;Gustavsson, Thomas;Markovitsi, Dimitra
采用稳态荧光上转换和时间相关单光子计数相结合的方法研究了小牛胸腺DNA的荧光。荧光光谱非常类似于由明亮的pi pi*态产生的化学计量混合单体发色团的荧光光谱，并与现有的天然DNA中激基复合体发射的图像形成对比。然而，DNA荧光衰变的时间跨度超过50年，98%的光子发射时间超过10ps。这些发现，结合最近对模型双链的研究，解释了暗态的参与，可能与电荷分离有关，作为明亮pi pi*态的再布居的储藏库。
The fluorescence of calf thymus DNA is studied by steady-state and time-resolved spectroscopy combining fluorescence upconversion and time-correlated single photon counting. The fluorescence spectrum is very similar to that of a stoichiometric mixture of monomeric chromophores, arising from bright pi pi* states, and contrasts with the existing picture of exciplex emission in natural DNA. Yet, the DNA fluorescence decays span over five decades of time, with 98% of the photons being emitted at times longer than 10 ps. These findings, in association with recent studies on model duplexes, are explained by the involvement of dark states, possibly related to charge separation, serving as a reservoir for the repopulation of the bright pi pi* states.