关键词: 光电化学生物传感器, 核酸, 催化发卡自组装, [Ru(NH₃)₆]Cl₃, CdS, TiO₂

Abstract: 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.

Key words: photoelectrochemical biosensor, nucleic acid, catalytic hairpin assembly, [Ru(NH₃)₆]Cl₃, CdS, TiO₂