DNA-纳米多孔羟基磷灰石修饰电极用于研究DNA与亚甲基蓝的相互作用

利用溶胶-凝胶法将具有优良生物相容性和独特吸附性的羟基磷灰石(HAp)修饰在玻碳电极上形成纳米多孔薄膜. 电化学实验结果证明该纳米多孔羟基磷灰石薄膜能有效地将双链DNA吸附于其表面. 采用循环伏安法系统研究了固定在HAp薄膜上的DNA与亚甲基蓝(MB)之间的相互作用. 实验结果表明, 在20～200 mV?s^－1扫描速度范围内该电极反应过程系表面反应控制; 在pH 6.0～7.4范围内, MB在DNA修饰电极上的峰电位随pH的增加而向负方向移动; 当磷酸盐缓冲溶液中的离子强度小于59 mmol?L^－1时, MB与DNA之间为静电作用, 当离子强度大于59 mmol?L^－1时, 二者之间既有静电作用, 也有部分嵌入作用. 根据Langmuir吸附公式, 得出MB与DNA之间的结合常数为4.2×10⁴ mol^－1?L.

DNA-Nano-porous Hydroxyapatite Modified Electrode Applied to the Study on the Interactions of DNA with Methylene Blue

Nano-porous hydroxyapatite (HAp) was prepared with sol-gel method to modify glassy carbon electrode (GCE) due to its excellent biocompatibility and particular adsorbability. Double-stranded (ds) DNA was immobilized by effective adsorption on the nano-porous hydroxyapatite modified GCE surface. The interactions of DNA immobilized on the HAp film with methylene blue (MB) were investigated by means of cyclic voltammetry (CV). The results show that the redox currents of MB at DNA modified electrode had linear relationship with scan rate from 20 to 200 mV?s^－1, as expected for a surface-controlled process. The anodic and cathodic peak potentials both shifted negatively with increasing pH from 6.0 to 7.4. The results show that the interaction of DNA with MB was an electrostatic mode when ionic strength of PBS was smaller than 59 mmol?L^－1, while there was not only electrostatic but also intercalative mode between them when the ionic strength of PBS was more than 59 mmol?L^－1. The binding constant of MB to DNA was calculated to be 4.2×10⁴ mol^－1?L according to Langmuir adsorption formula.