Author(s)

Shasha Su^1,2, Shu Zhang^1,2,3, Jiang Huang^2,4, Xi Chen^1,2, Yan Li¹, Lichao Fang¹, Jun Deng¹, Fei Mo^2,3*, Junsong Zheng^1*

¹Department of Clinical and Military Laboratory Medicine, College of Medical Laboratory Science, Army Medical University, Shapingba District, Chongqing, China.
²Department of Basic Clinical Laboratory Medicine, School of Clinical Laboratory Science, Guizhou Medical University, Yunyan District, Guiyang, China.
³Department of Clinical Laboratory, Affiliated Hospital of Guizhou Medical University, Guiyang, China.
⁴Department of Biochemistry, Affiliated Hospital of Guizhou Medical University, Guiyang, China.

DNA methylation plays a significant role in various biological events, and its precise determination is vital for the prognosis and treatment of cancer. Here, we proposed an ultrasensitive electrochemical biosensor for the quantitative analysis of multiple methylation-locus in DNA sequence via DNA anchoring the gold nanoparticles (DNA-AuNPs) and bienzyme dual signal amplifications. After the target DNA captured by the DNA-AuNPs of the biosensor, the methyl-CpG binding protein MeCP2 could specifically conjugate to the methylation-loci in the double-stranded DNA. Successively, the glucose oxidase (GOD) and horseradish (HRP) co-labeled antibody captured the His tagged MeCP2, which leads to a cascade enzymatic catalysis of the substrates to yield a detectable electrochemical signal. Both the two strategies, including the high content of DNA-AuNPs and the associated catalysis of bienzyme, dramatically enhanced the sensitivity of the biosensor. The response current elevated with the increasing numbers of methylation-locus, thus the multiple methylated DNA was identified by detecting the corresponding current signals. This method could detect the methylated target as low as 0.1 fM, and showed a wide linear range from 10 - 15 M to 10 - 7 M. Besides, the long-term stability and repeatability of the biosensor were also validated. The prepared electrochemical immunosensor exhibits ultrasensitivity through the bienzyme labeling process, which can be applied for the detection of DNA methylation with low concentration.

DNA Methylation, Electrochemistry, Biosensor, AuNPs, Bienzyme

Su, S. , Zhang, S. , Huang, J. , Chen, X. , Li, Y. , Fang, L. , Deng, J. , Mo, F. and Zheng, J. (2020) Electrochemical Biosensor for Multiple Methylation-Locus Analysis Based on DNA-AuNPs and Bienzymatic Dual Signal Amplifications. American Journal of Analytical Chemistry, 11, 61-74. doi: 10.4236/ajac.2020.112005.