紫精与八元瓜环的超分子组装及光切割质粒DNA

Supramolecular Self-assembly Between Viologen and Cucurbit[8]uril and Its Application for the DNA Photocleavage

利用紫精可以活化水中溶解氧的特性,设计合成了苯-紫精化合物(BEV).利用紫外吸收、电化学及核磁等方法研究了BEV与八元瓜环CB[8]之间的相互作用.实验结果表明,2种化合物可以进行主客体超分子自组装形成1∶1的二元包合物BEV-CB[8].同时,分别考察了化合物BEV和BEV-CB[8]与小牛胸腺DNA的相互作用,并采用琼脂糖凝胶电泳研究了氙灯光照下化合物对pBR322 DNA的切割能力.结果表明,CB[8]的引入改变了化合物BEV与DNA的作用方式,使嵌入作用和静电作用增强.光照结果说明只有超分子BEV-CB[8]在光照下可以完全切割质粒DNA,即CB[8]的存在明显提高了BEV对质粒DNA的切割效率.

Combining supramolecular chemistry with biochemistry was a new research direction.In this paper,self-assembly between a host compound CB[8] with a guest molecule benzyl viologen（BEV） was examined by UV absorption measurement,cyclic voltammetric method and 1H NMR technique.The experimental results revealed that CB[8] included benzyl and part of pyridinum of BEV to form binary compounds BEV-CB[8],and when BEV2＋ was reduced to BEV＋·,a new stable ternary complex（BEV＋·）2/CB[8] would be formed.The two kinds of viologens,BEV and BEV-CB[8],were used for DNA photocleavage stu-dies in physiological environment following the research results that CB[8] could enhance the interaction between BEV and CT DNA with intercalation and electrostatic interaction.Only 50 μmol/L of the complex BEV-CB[8] could cleave SC pBR 322 DNA completely compared with BEV,which showed no ability for DNA clea-vage under the irradiation of Xe lamp.The main reason was that BEV2＋ was reduced to BEV＋· under irradiation and CB[8] bound BEV＋· tightly to form（BEV＋·）2/CB[8],which prolonged the lifetime of viologen radical BEV＋·,causing the dissolved oxygen in water activation and the reactive oxygen species,· OH and O-·2,could cleave SC pBR 322 DNA.The results indicate an important application by host molecule CB[n] in supramolecular chemistry,which gives an obviously evidence for the field of DNA cleavage.