An ultrasensitive electrochemiluminescence assay for nucleic acid detection based on carboxyl functionalized polymer dots

Abstract An electrochemiluminescence (ECL) sensing platform for ultrasensitive detection of miRNA-122 was developed by integrating novel emitters of polymer dots (Pdots) and signal amplification strategies. Firstly, we synthesized a novel polymer with carboxyl group which consisted of fluorene derivate and benzothiadiazole, corresponding Pdots materials were also prepared by nanoprecipitation method. Subsequently, an ECL biosensor based on the Pdots for miRNA-122 detection was constructed, which combines the amplification of duplex-specific nuclease (DSN)-assisted target recycling and rolling circle amplification (RCA) in-situ on the electrode. After the two-step amplification, amounts of ferrocene modified DNA (Fc-DNA) were captured on the electrode, which could quench the ECL signal of the Pdots. Ultimately, the proposed sensor presented a wide linear range of 0.1 fM to 100 pM and a low detection limit of 36 aM to miRNA-122. This work not only propose a universal paradigm for nucleic acid detection with good specificity and high sensitivity, but also provide an approach for designing novel Pdots to construct ECL sensor conveniently.