三维有序金掺杂纳米TiO_2修饰电极用于抗肿瘤药物与DNA相互作用的研究

利用模板法在氧化铟锡(ITO)电极表面制备了三维有序多孔结构的金掺杂纳米Ti O2薄膜修饰电极(3DOM GTD/ITO),并在此修饰电极上成功固定小牛胸腺DNA(ct DNA),从而构建了一种新型的DNA生物传感器(DNA/3DOM GTD/ITO),并通过透射电镜(TEM)、扫描电镜(SEM)对修饰电极的表面形貌进行表征。采用电化学交流阻抗(EIS)法研究了ct DNA在3DOM GTD/ITO修饰电极表面的固定情况,结果表明,ct DNA已被成功地固定在3DOM GTD/ITO修饰电极表面。采用循环伏安法、微分脉冲伏安法等电化学方法研究了抗肿瘤药物槲皮素(Qu)在3DOM GTD/ITO修饰电极表面的电化学性质及与ct DNA的相互作用。结果表明,Qu在3DOM GTD/ITO修饰电极表面有1对准可逆的氧化还原峰,其氧化还原反应为2电子和2质子的转移过程。Qu可与固定在修饰电极上的ct DNA发生较强的结合作用,其结合常数(K)为3.61×106L/mol。循环伏安实验、紫外-可见吸收光谱、分子荧光光谱、圆二色性光谱均表明Qu与ct DNA之间的相互作用模式为嵌插作用。Qu与ct DNA的碱基结合具有序列选择性,对Qu与聚(d G-d C)及聚(d A-d T)的结合常数进行计算,得到结合常数比K(d G-d C)/K(d A-d T)=3.5,表明Qu与ct DNA发生嵌插作用时更倾向于结合在GC富集区域。

Study on Interaction between Antitumor Drug and DNA by Three-dimensionally Ordered Gold-nanoparticle-doped Titanium Dioxide Modified Electrode

A novel DNA biosensor was fabricated with three-dimensionally ordered macroporous gold-nanoparticle-doped titanium dioxide(3DOM GTD) film on the indium-tin oxide(ITO) electrode surface by the colloidal crystal template technique,and calf thymus DNA(ctDNA)was immobilized on the 3DOM GTD/ITO successfully.The morphology of the modified electrode was characterized by transmission electron microscopy(TEM) and scanning electron microscopy(SEM).The immobilization of ctDNA on the surface of 3DOM GTD/ITO modified electrode was investigated by electrochemical impedance spectroscopy(EIS).The EIS experimental results showed that ctDNA was successfully immobilized on the 3DOM GTD/ITO modified electrode.The electrochemical properties of the antitumor drug quercetin (Qu) and the interaction between Qu and ctDNA were studied on 3DOM GTD/ITO modified electrode by cyclic voltammograms (CV) and differential pulse voltammograms(DPV) method.The result showed that Qu had a pair of quasi-reversible redox peak on 3DOM GTD/ITO modified electrode,and the transfer process of 2 electrons and 2 protons was an involved in the electrode reaction.There was a strong interaction between Qu and ctDNA immobilized on the modified electrode,and the binding constant K was 3.61×106L/mol.The binding mode between Qu and ctDNA was an intercalation confirmed by CV,UV-Vis absorption spectra (UV-Vis),fluorescence spectra(FL) and circular dichroism spectra(CD) experiments. The sequence selectivity of binding between Qu and ctDNA was investigated,and the binding constants of Qu and poly(dG-dC) and poly(dA-dT) were calculated, respectively, according to the results of CV experiments.The binding constant ratio K(dG-dC)/K(dA-dT) was obtained to be 3.5,indicating that Qu bound to the GC region preferentially when Qu interacted with ctDNA.