Gene Detection by Light-to-electric Converting Intercalator and Its Application to DNA

点击翻译按钮获取中文摘要

In this research we developed a novel detection system of DNA duplex using a light-to-electric conversion. The principle of the detection of DNA duplex formation is as follows. 1) The gold electrode modified by single stranded DNA was prepared. 2) When double stranded DNA is formed, ruthenium complex will intercalate and will be concentrated on the electrode surface. 3) Then the visible light is irradiated to the electrode, photocurrent caused by excitation of ruthenium complex will be observed.We used a polypyridyl ruthenium complex carrying DNA intercalating ligand for DNA detection. Ru(bpy)_3 was used as a control compound. Ru(bpy)_2dppz was used as a ruthenium complex carrying a DNA intercalating part. Furthermore, we synthesized NDI-Ru_2 as a threading intercalator carrying ruthenium complex. This type of compound has a smaller dissociation rate from DNA duplex, because it has threading intercalating part connected to two bulky groupsA DNA-immobilized gold electrode was dipped into the solution containing the light-to-electric converting intercalator (Ru(bpy)_3, Ru(bpy)_2dppz, NDI-Ru_2). When the visible light was irradiated to the surface of the electrode, continuous photocurrent occurred in the presence of tertiary amine as an electron donor. The amount of photocurrent increased by 36% in the case of Ru(bpy)_2dppz, 86% in the case of NDI-Ru_2 after the formation of double-stranded DNA. This result suggested that the metallointercalator was concentrated on the surface of gold electrode by its affinity to DNA duplex. In the case of NDI-Ru_2, we consider that electron was smoothly transferred from ruthenium to gold electrode through naphthalenediimide because NDI acts as an electron acceptor. In conclusion, we could discriminate between double stranded and single stranded DNA from the magnitude of the photocurrent using a ruthenium intercalator.