标题：Label-free and highly sensitive electrochemical detection of E-coli based on rolling circle amplifications coupled peroxidase-mimicking DNAzyme amplification
作者：Guo, Yuna; Wang, Yu; Liu, Su; Yu, Jinghua; Wang, Hongzhi; Wang, Yalin; Huang, Jiadong
作者机构：[Guo, Yuna; Yu, Jinghua; Wang, Hongzhi; Huang, Jiadong] Univ Jinan, Sch Chem & Chem Engn, Key Lab Chem Sensing & Anal, Shandong Univ, Jinan 250022, Pe 更多
通讯作者地址：[Huang, JD]Univ Jinan, Sch Chem & Chem Engn, Key Lab Chem Sensing & Anal, Shandong Univ, Jinan 250022, Peoples R China.
来源：BIOSENSORS & BIOELECTRONICS
关键词：Label-free electrochemical assay; RCA; Peroxidase-mimicking DNAzyme; amplification; E. coil detection
摘要：In this work, a simple, label-free, low cost electrochemical biosensor for highly sensitive and selective detection of Escherichia coil has been developed on the basis of rolling circle amplification (RCA) coupled peroxidase-mimicking DNAzyme amplification. A aptamer-primer probe (APP) containing anti-E. coil aptamer and a primer sequence complementary to a circular probe, which includes two G-quadruplex units, is used for recognizing target and triggering RCA-based polymerase elongation. Due to RCA coupled DNAzyme amplification strategy, the presence of target E. coil leads to the formation of numerous G-quadruplex oligomers on electrode, which folds into G-quadruplex/hemin complexs with the help of K+ and hemin, thus generating extremely strong catalytic activity toward H2O2 and giving a remarkably strong electrochemical response. As far as we know, this work is the first time that RCA coupled peroxidase-mimicking DNAzyme amplification technique have been integrated into electrochemical assay for detecting pathogenic bacteria. Under optimal conditions, the proposed biosensor exhibits ultrahigh sensitivity toward E. coil with detection limits of 8 cfu mL(-1) and a detection range of 5 orders of magnitude. Besides, our biosensor also shows high selectivity toward target E. coil and has the advantages in its rapidness, low cost, simplified operations without the need of electrochemical labeling steps and additional labile reagents. Hence, the RCA coupled peroxidase-mimicking DNAzyme amplification-based electrochemical method might create a useful and practical platform for detecting E. coil and related food safety analysis and clinical diagnosis. (C) 2015 Elsevier B.V. All rights reserved.