DNA Biosensors for Medical Diagnosis

大多数生物传感器依赖于蛋白质，如酶和抗体，而DNA也是生物亲和反应中的重要宿主分子。DNA固定化电极有望成为一种实用的医学诊断工具。我们通过化学吸附将DNA双链固定在Au电极上。亚铁氰化物的循环伏安图与DNA修饰电极。当加入DNA结合分子时，CV峰电流随其浓度的增加而增加。峰电流与所加化合物的对数浓度呈S形关系。包含DNA的传感器被证实是用于评估DNA和DNA结合分子之间的相互作用的有用工具。此外，该修饰电极还能与双螺旋DNA特异性结合的抗DNA抗体发生反应，抗DNA抗体已被用作系统性红斑狼疮（SLE）的标志分子。我们还开发了一种新的电化学基因检测技术，其中固定在Au电极上的寡脱氧核苷酸（ODN）与靶DNA形成了一种新型的复合物，并产生响应。修饰电极的微分脉冲伏安图显示，当用靶DNA处理电极时，由于探针DNA的二茂铁部分的氧化，修饰电极出现了一个明显的阳极峰，而用错配对照处理的修饰电极只观察到一个轻微的阳极峰。这些结果表明，靶分子与固定在电极上的ODN通过互补碱基配对而被识别。

Most of biosensors rely on proteins such as enzymes and antibodies, while DNA is also an important host molecule in biological affinity reactions. DNA-immobilized electrode may be a usuful tool for medical diagnosis. We immobilized DNA double strands on a Au electrode via chemisorption. Cyclic voltammograms of ferrocyanide were taken with the DNA-modified electrode. When adding DNA-binding molecules, the CV peak currents increased with increasing concentration of them. The peak current showed a sigmoidal relationship with the logarithmic concentration of the added compound. The sensor comprising DNA was confirmed to be a useful tool for evaluation of the interaction between DNA and DNA-binding molecules. In addition, this DNA-modified electrode was found to respond to anti-DNA antibody which specifically binds to double helical DNA.Anti-DNA antibodies has been used as marker molecule of Systemic Lupus Erythematossus (SLE). We also developed a novel electrochemical technique for gene detection in which the sandwich-type complex from oligodeoxynucleotide (ODN) immobilized on Au electrode, target DNA,and the ferrocenyl ODN is formed to give a response. Differential pulse voltammograms for the modified electrode showed a significant anodic peak due to the oxidation of ferrocene moiety of the probe DNA,when the electrode was treated with the target DNA.On the other hand, only a slight peak was observed for the modified electrode which was treated similarly with the mismatch control. These results indicate that the target was recognized by means of complementary base-pairing with the ODN immobilized on thw electrode.