An electrochemical sensor based on label-free functional allosteric molecular beacons for detection target DNA/miRNA

作者：Cai Z; Song Y; Wu Y; Zhu Z; James Yang C; Chen X^*

来源：Biosensors and Bioelectronics, 2013, 41(1): 783-788.

DOI：10.1016/j.bios.2012.10.002

• MicroRNA
• Molecular beacons
• RSV

We report two novel electrochemical sensors (E-sensors) for the detection of target DNA and miRNA. The E-sensors were fabricated using label-free functional allosteric molecular beacons (aMBs), which can form streptavidin aptamers to bind to streptavidin peroxidase polymer and so generate catalytic currents in the presence of the targets. These E-sensors eliminate the antigen antibody interactions which require sophisticated DNA modification. During the experiment, we found a pair of CV peaks located at around 0.17V. These peaks contributed to the redox reaction between TMB and TMB+, and the adsorption-desorption process of TMB+ to the negative aMB backbone. When the E-sensor was hybridized with the complement of the aMB sequence, a pair of CV peaks were found at around 0.47V which were related to the redox reaction between TMB+ and TMB2+, and the process of intercalation of the planar structure of TMB2+ to dsDNA. The RSV-aMB E-sensor could detect 44amol RSV DNA in the 4μL sample and performed well in complicated biological environments. The let-7a-aMB E-sensor reached a detection limit of 13.6amol let-7a miRNA in the 4μL sample and showed good selectivity for one base mismatched miRNA.