Ultrasensitive SQDs-based electrochemiluminescence assay for determination of miRNA-141 with dual-amplification of co-reaction accelerators and DNA walker

Abstract

Herein, a novel electrochemiluminescence (ECL) biosensor for sensitive detection of miRNA-141 was fabricated based on sulfur quantum dots (SQDs) with the strategies of co-reaction accelerators and endonuclease recycling dual-amplification. Using SQDs as an ECL signal probe, the DNA walker was immobilized on the modified electrode for dual-amplification. At first, convex hexoctahedral palladium@gold nanoparticles (Pd@Au NPs) which acted as co-reaction accelerators could catalyze the dissociation of co-reactants into active radicals and significantly promote the ECL emission of SQDs. Secondly, the Pd@Au NPs acting as the carrier for DNA walker provided an enzymatic-cycling amplification strategy for ultrasensitive and specific detection of miRNA-141. Thereinto, the restriction endonuclease Nt.BbvCI recognized the specific sequence and cleaved the ferrocene-labeled oligonucleotides (Fc-S2) from the double-stranded DNA substrate. Thus, ferrocene (Fc) was detached far away from the biosensor’s surface and the exposed Pd@Au NPs acted as co-reaction accelerators to enhance ECL signal. This greatly improved the ECL emission efficiency of SQDs and the sensitivity of the biosensor. Based on the dual-amplification strategy, the ECL biosensor had a detection range from 10 fM to 300 pM with a low detection limit of 1.39 fM. The present strategy enabled highly accurate and sensitive detection of miRNA-141 in multifarious bioanalysis and clinical diagnosis.