Bidirectional Electrochemiluminescent Sensing: An Application in Detecting miRNA-141

This paper describes a bidirectional electrochemiluminescence (ECL) biosensor for the detection of microRNA-141 (miRNA-141) with aM level detection limit and two-segment 8 orders of magnitude linear range. Hemin/G-quadruplex DNAzyme was assembled on carbon nitride nanosheets and Au nanoparticles modified electrode. The ECL of carbon nitride nanosheets could be enhanced by the right amount of H₂O₂ (no more than 10 mM) and then inhibited by excessive H₂O₂ when 0.1 M K₂S₂O₈ acted as coreactant. In the presence of excessive H₂O₂ (20 mM), a recovery of ECL intensity was obtained due to the catalytic reduction of H₂O₂ caused by hemin/G-quadruplex DNAzyme at lower target concentrations, and then an ECL decrease occurred mainly by biocatalytic precipitation (BCP)-induced charge transfer resistance on the electrode surface at higher target concentrations. Therefore, based on the change of the ECL intensity caused by the catalytic reduction of H₂O₂ and BCP, a highly sensitive bidirectional miRNA sensor with ultralow detection limit of 7.9 aM and wide linear range from 10^-17 to 10^-9 M was obtained. This work could attract more attention on the study of multiple mechanisms and also provides a more sensitive and precise method for the analysis of nucleic acids.