Synthesizing anode electrochemiluminescent self-catalyzed carbon dots-based nanocomposites and its application in sensitive ECL biosensor for microRNA detection

In this work, a novel self-catalyzed carbon dots-based electrochemiluminescence (ECL) luminophore was prepared by loading the amino modified carbon dots onto the surface of AuNPs modified TiO(2)NPs (CDs-AuPEI@TiO2) and applied in sensitive ECL biosensor for miRNA-21 detection. Significantly, the prepared CDs-AuPEI@TiO2 nanocomposites exhibited strong initial ECL intensity for the acceleration of TiO(2)NPs towards to the electrochemical reduction of co-reactive H2O2, addressing the shortcomings of the strong oxidizing nature of persulfate in traditional CDs-based ECL biosensings and enhancing the detection sensitivity. Moreover, by target-induced catalytic hairpin assembly (CHA) amplification, a large number of quenching groups could be released and captured on the electrode surface, further improving the detection sensitivity. As a consequence, the ECL response of the proposed biosensor gradually decreased as the concentration of miRNA-21 increasing from 0.1 fM to 10 pM with the detection limit of 0.03 fM. The strategy provided in this work opens up a new way for miRNA detection in actual cell using self-catalyzed carbon dots-based ECL biosensing platform.