Molecular beacon immobilized on graphene oxide for enzyme-free signal amplification in electrochemiluminescent determination of microRNA
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An electrochemiluminescence (ECL) based biosensor is described for determination of microRNAs in the A549 cell line. Firstly, graphene oxide (GO) is dripped onto a glassy carbon electrode surface to form an interface to which one end of the capture probe (with a stem-loop structure) can be anchored through π-interaction via dangling unpaired bases. The other end of the capture probe is directed away from the GO surface to make it stand upright. Target microRNAs can open the hairpin structure to form a double-stranded DNA-RNA structure. Two auxiliary probes, generating a hybridization chain reaction, are used to elongate the DNA duplex. Finally, doxorubicin-modified cadmium telluride quantum dot nanoparticles (Dox-CdTe QD) are intercalated into the base pairs of the hybrid duplexes to act as signalling molecules. The ECL signal of the Dox-CdTe QD increases proportionally with the concentration of microRNAs, specifically for microRNA-21. The assay covers a wide linear range (1 fM to 0.1 nM), has a low detection limit for microRNA-21 (1 fM), and is selective, reproducible, and stable.
KeywordsCdTe Doxorubicin π-stacking interaction DNA probe Hybridization chain reaction
This work was financially supported by the National Natural Science Foundation of China (No. 21527808, 21475006) and Beijing municipal high level innovative team building program (IDHT 20180504).
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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