Concatenated Catalytic Hairpin Assembly/Hyperbranched Hybridization Chain Reaction Based Enzyme-Free Signal Amplification for the Sensitive Photoelectrochemical Detection of Human Telomerase RNA
Yanxin Chu†§, An-Ping Deng*†, Wenjing Wang*‡, and Jun-Jie Zhu*§（朱俊杰）
† The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
‡ State Key Laboratory of Agricultural Microbiology, College of Science, Huazhong Agricultural University, Wuhan 430070, People’s Republic of China
§ State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, People’s Republic of China
Anal. Chem., 2019, 91 (5), 3619--3627
Human telomerase RNA (hTR), an important biomarker for cancer diagnosis, is the template for the synthesis of telomeric DNA repeats and is found to be 7-fold overexpressed in tumor cells. Herein, we present a photoelectrochemical (PEC) biosensor for hTR detection coupled with a novel amplification strategy based on cascades of catalytic hairpin assembly (CHA) and hyperbranched hybridization chain reaction (HB-HCR). At the electrode surface, thiolated hairpin 1 probes were immobilized on deposited CdS nanoparticles via a Cd–S bond. In the presence of target hTR, a CHA reaction was triggered and the exposing of trigger1 could further initiate an HB-HCR reaction to form abundant hemin/G-quadruplex DNAzymes containing dendritic DNA structure. The DNAzymes’ catalytic precipitation of 4-chloro-1-naphthol (4-CN) by H2O2subsequently took place on the surface of the PEC electrode and efficiently suppressed the photocurrent output. Therefore, the change of photocurrent response had a positive linear relationship with logarithmic value of hTR concentration varying from 200 fM to 20.0 nM with a limit of detection (LOD) of 17.0 fM. The LOD for CHA/HB-HCR was about 8.8-fold lower than that of CHA/linear-branched HCR (CHA/LB-HCR) and 547-fold lower than that of CHA. By coupling the feature of high signal amplification capacity for DNA nanotechnology, a prominently stable, reproducible, and selective PEC biosensor was successfully constructed and applied in hTR detection.