基于电中性锇配合物的低背景DNA电化学传感器

采用紫外光谱和电化学方法研究了一种电中性锇配合物Os(DPPZ)(PC)(H₂O)DPPZ=联吡啶并[3,2-a,2',3'-c]吩嗪, PC=2,6-吡啶二羧酸}与DNA的相互作用. 紫外光谱结果表明, DNA的加入引起配合物特征吸收峰的减色及红移效应, 说明二者之间存在嵌插作用. 循环伏安实验结果表明, 配合物溶液中加入DNA后, 氧化还原峰电流降低且式电位正移, 证实了二者之间的嵌插作用模式. 将该配合物作为杂交指示剂对CaMV35S启动子基因片段进行检测发现, 在单链探针DNA修饰电极上未观察到指示剂的电化学信号, 而在杂交后的双链DNA电极上呈现灵敏的电化学响应, 表明传感器具有较高的信噪比. 定量分析实验结果表明, 在最佳条件下, 杂交指示剂在传感器上的还原峰电流与目标序列浓度在8.0×10^-10~2.8×10^-9 mol/L范围内呈良好的线性关系. 选择性实验结果表明, 该传感器对互补序列、碱基错配序列和非互补序列具有良好的识别能力.

Low-background Electrochemical DNA Biosensor Using an Electrically Neutral Osmium Complex as Hybridization Indicator

The interaction between an electrically neutral osmium complex Os(DPPZ)(PC)(H₂O) (DPPZ=dipyrido(3,2-a,2',3'-c)phenazine, PC=2,6-pyridine dicarboxylic acid) and DNA was investigated by UV absorption spectroscopy and electrochemical methods. The hypochromic and red-shift effects of the characteristic absorption peak of Os(DPPZ)(PC)(H₂O) after interaction with DNA suggested that the complex bound to DNA via an intercalative mode, which was testified by the positive shift of the formal potential of the complex in cyclic voltammetric experiments. When the complex was utilized as a hybridization indicator for the detection of CaMV35S promoter gene fragments, no electrochemical response was observed on the probe of DNA modified electrode. A sensitive electrochemical signal, however, was obtained on the hybridized electrodes, suggesting that the DNA biosensor possessed a high signal-to-noise ratio. The complementary target sequence could be quantified over the range from 8.0?0^-10 mol/L to 2.8?0^-9 mol/L. The hybridization specificity experiments further indicated that the biosensor could well discriminate the complementary sequences from the base-mismatched and the non-complementary sequences.