Label-free and highly sensitive electrochemical detection of E. coli based on rolling circle amplifications coupled peroxidase-mimicking DNAzyme amplification.
In this work, a simple, label-free, low cost electrochemical biosensor for highly sensitive and selective detection of Escherichia coli has been developed on the basis of rolling circle amplification (RCA) coupled peroxidase-mimicking DNAzyme amplification. A aptamer-primer probe (APP) containing anti-E. coli 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. coli 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. coli with detection limits of 8cfumL(-1) and a detection range of 5 orders of magnitude. Besides, our biosensor also shows high selectivity toward target E. coli 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. coli and related food safety analysis and clinical diagnosis.
Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
Yuna
Y
Guo
School of Biological Sciences and Technology, University of Jinan, Jinan 250022, PR China.
Yu
Y
Wang
School of Resources and Environment, University of Jinan, Jinan 250022, PR China.
Su
S
Liu
Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
Jinghua
J
Yu
Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
Hongzhi
H
Wang
School of Resources and Environment, University of Jinan, Jinan 250022, PR China.
Yalin
Y
Wang
Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China; School of Biological Sciences and Technology, University of Jinan, Jinan 250022, PR China. Electronic address: chm_huangjd@ujn.edu.cn.
Jiadong
J
Huang
D015374:Biosensing Techniques / Q000379:methods*; D021881:DNA, Catalytic / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000379:methods*; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification*; D054856:G-Quadruplexes; D006861:Hydrogen Peroxide / Q000737:chemistry; D053770:Nanowires / Q000737:chemistry; D021141:Nucleic Acid Amplification Techniques / Q000379:methods; D009195:Peroxidase / Q000737:chemistry
D021881:DNA, Catalytic; D006861:Hydrogen Peroxide; D009195:Peroxidase
E. coli detection; Label-free electrochemical assay; Peroxidase-mimicking DNAzyme amplification; RCA