A new photoelectrochemical biosensors based on DNA conformational changes and isothermal circular strand-displacement polymerization reaction.
We report a strategy for the transduction of DNA hybridization into a readily detectable photoelectrochemical signal by means of a conformational change analogous to electrochemical DNA (E-DNA) approach. To demonstrate the effect of distance change for photosensitizer to the surface of electrode on the change of photocurrent, photosensitizer Ru(bpy)(2)(dcbpy)(2+) tagged DNA stem-loop structures were self-assembled onto a nanogold modified ITO electrode. Hybridization induced a large conformational change in DNA structure, which in turn significantly altered the electron-transfer tunneling distance between the electrode and photosensitizer. The resulting change in photocurrent was proportional to the concentration of DNA in the range of 1.0×10(-10)-8.0×10(-9)M. In order to improve the sensitivity of the photoelectrochemical biosensor, an amplified detection method based on isothermal strand displacement polymerization reaction was employed. With multiple rounds of isothermal strand replication, which led to strand displacement and constituted consecutive signal amplification, a detection limit of 9.4×10(-14)M target DNA was achieved.
Key Laboratory of Biochemical Analysis, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, PR China. zhangxr7407@126.com
Xiaoru
X
Zhang
Yunpeng
Y
Xu
Yanqing
Y
Zhao
Weiling
W
Song
D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000032:analysis*; D055664:Electrochemical Techniques / Q000379:methods; D004566:Electrodes; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization / Q000379:methods*; D009942:Organometallic Compounds / Q000737:chemistry*; D055668:Photochemical Processes; D017319:Photosensitizing Agents / Q000737:chemistry*; D058105:Polymerization; D012680:Sensitivity and Specificity
D009942:Organometallic Compounds; D017319:Photosensitizing Agents; D015082:2,2'-Dipyridyl; C058014:ruthenium bis(bipyridine)dicarboxybipyridine; D004247:DNA