基于催化发卡自组装和 Ru(NH3)63+ 的核酸光电化学灵敏分析

基于催化发卡自组装反应（CHA）和电活性材料Ru(NH₃)₆]Cl₃，发展了一种“信号增强”型光电化学生物传感器，实现了核酸的灵敏检测. 首先，采用逐层离子吸附法（SILAR）将CdS 固定于TiO₂/ITO 电极表面. 光电材料CdS 不仅能够将TiO₂ 的吸收范围从紫外光区拓展到可见光区，而且还能提高光电转换效率. 之后，通过Cd-S 键将捕获DNA（C-DNA）固定于CdS/ TiO₂/ITO 电极表面. 与此同时，将Au 结合的发卡DNA 探针1（Au-HP1），发卡DNA 探针2（HP2）和目标DNA（T-DNA）混合物于溶液中进行CHA 反应，得到大量的Au-HP1:HP2 复合物. 再通过Au-HP1:HP2 复合物与C-DNA 的杂交反应将大量的双链DNA 引入到电极表面. 最后，将电活性物质Ru(NH₃)₆³⁺嵌入DNA 的磷酸骨架中，从而使得光电流大幅度的增强. 该光电生物传感器检测核酸的线性范围为10 fmol·L^-1 到 1500 fmol·L^-1，检测线为6.19 fmol·L^-1，在生物分析、新药筛选以及疾病的早期诊断等方面具有潜在的应用前景.

Sensitive Photoelectrochemical Assay of Nucleic Acids Based on Catalytic Hairpin Assembly and Ru(NH3)63+

A simple “signal-on” photoelectrochemical (PEC) sensing platform for sensitive assay of nucleic acids was developed by coupling catalytic hairpin assembly (CHA) signal amplification strategy with Ru(NH₃)₆³⁺. Herein, cadmium sulfide (CdS) was deposited on the TiO₂/indium tin oxide (ITO) electrode by a method of successive ionic layer adsorption and reaction (SILAR), serving as one kind of photoelectric material to broaden absorption range of TiO₂ and to improve the photoelectric conversion efficiency. Thereafter, the capture DNA (C-DNA) was immobilized on the CdS/TiO₂/ITO electrode. Simultaneously, Au-hairpin DNA probe 1 (Au-HP1) and hairpin DNA probe 2 (HP2) were able to hybridize to produce many Au-HP1:HP2 complexes under the existence of target DNA (T-DNA) based on CHA process. After that, C-DNA could capture Au-HP1:HP2 complex, leading to lots of double-stranded DNAs on the electrode to load numerous Ru(NH₃)₆³⁺, which resulted in a remarkable increase of photocurrent. As a result, a wide linear range (10 fmol·L^-1 to 1500 fmol·L^-1) and a low detection limit (6.19 fmol·L^-1) toward T-DNA were achieved. The developed method would have great potential applications in bioanalysis, screening of new drugs and early disease diagnosis.