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.