Development of Biosensor Comprising DNA as Affinity Ligand

生物传感器等传感技术中的分子识别功能通常由酶和抗体等蛋白质提供。另一方面，DNA也是生物亲和反应中重要的宿主分子。本研究开发了一种新的金属电极固定双螺旋DNA的修饰化学方法。研究了该电极在生物亲和传感领域的应用前景。DNA双链通过化学吸附固定在金电极上，即与含硫部分配位。用dna修饰电极对亚铁氰化物/铁氰化物氧化还原对进行循环伏安。当加入著名的抗疟疾药物奎纳克里时，峰值电流随着药物浓度的增加而增加。峰值电流在10^<-7>-5 × 10^<-7 >m范围内与醌浓度基本呈线性关系，超过8x^<-7 >m时达到饱和。阳离子药物与固定化DNA的结合应减少多阴离子DNA与阴离子氧化还原偶离子之间的静电斥力，从而使电流强度增强。此外，发现dna修饰电极可用于“基因传感器”。该传感器不仅可用于DNA的测量，还可用于评价DNA与一系列DNA结合药物之间的相互作用。

A molecular recognition function employed in sensing techniques such as biosensors is usually provided by proteins including enzymes and antibodies. On the other hand, DNA is also an important host molecule in biological affinity reactions. We have developed in this study a new modification chemistry for immobilizing double-helical DNA on metal electrode. Some possible application of the electrode for bioaffinity-based sensing has been studied.DNA double strands were immobilized on a Au electrode via chemisorption, i.e., a co-ordination to Au with a sulfur-containing moiety. Cyclic voltammograms of ferrocyanide/ferricyanide redox couple were taken with the DNA-modified electrode. When adding quinacrine, the well-known antimalarial drug, the peak currents increased with increasing concentration of the drug. The peak current showed almost a linear relationship with the concentration of quinacrine in the range of 10^<-7>-5x10^<-7>M and then saturated beyond the concentration of 8x^<-7>M.The binding of the cationic drug to the immobilized DNA should reduce the electrostatic repulsion between the polyanionic DNA and the anionic redox couple ions, resulting in the enhancement of the current intensity.In addition, the DNA-modified electrode was found to be useful for"gene sensor". The sensor comprising DNA as a receptive component can be used for not only the measurement of DNA but also the evaluation of the interaction between DNA and a family of DNA-binding drugs.