荧光及吸收光谱法研究β-环糊精-硫堇包合物与DNA的相互作用

Fluorescence and Visible Spectroscopic Studies on Interaction of β-Cyclodextrin-Thionine Inclusion Complex with DNA

用荧光及可见光谱方法研究了β-环糊精对硫堇的包合以及β-环糊精-硫堇包合物与DNA的相互作用。在pH 7.2的PBS缓冲液中,β-环糊精以1∶1包合硫堇,包合常数为527 L.mol-1(可见光谱法)、444L.mol-1(荧光法);DNA的引入使环糊精-硫堇包合物的吸收波长红移,吸光峰强度降低;环糊精-硫堇包合物的荧光发生蓝移并有猝灭现象,猝灭常数为6.12×104L.mol-1。荧光及可见光谱数据表明,环糊精-硫堇包合物以嵌入方式与DNA发生相互作用,其结合比是1∶1。

The inclusion of β-cyclodextrin （CD） for thionine （TH） and the interaction of DNA with CD-TH inclusion complex were investigated by fluorescence and visible absorption spectrometry. TH with β-CD formed a 1 ： 1 inclusion complex with the stability constant of 527 L·mol^-1 （visible spectrometry）/444 L ·mol^-1（fluorescence） in the pH 7. 2 PBS buffer solutions. The addition of DNA makes the absorbance of the inclusion complex decrease and the absorption spectrum shift toward long wavelengths. The fluorescence experiments indicated that the presence of DNA makes the emission peak of CD-TH shift toward short wavelengths and the fluorescence of inclusion complex quench, and the quenching constant was calculated to be 6. 12 ×10^4 L·mol^-1 by Stern-Volmer method. All the data confirmed that CD-TH reacted with DNA in intercalative mode, and the binding numbers and the binding constant were estimated to be 1 and 3.47×10^4 L·mol^-1 by spectrophotometry.