Potential- and Color-Resolved Electrochemiluminescence of Polymer Dots for Array Imaging of Multiplex MicroRNAs

The development of electrochemiluminescence (ECL) emitters remains a great research interest in ECL analysis. Herein, luminol-doped polymer dots (L-Pdots) and diethylamine-coupled Pdots (N-Pdots) were synthesized to design a both potential- and color-resolved ECL strategy. L-Pdots showed the maximum ECL emission at 450 nm in the presence of hydrogen peroxide at +0.6 V, while the maximum emission of N-Pdots was at 675 nm under +1.0 V. This strategy was conveniently used to construct a novel ECL array imaging method for high-throughput detection of two microRNAs (miRNAs). The array was prepared with the mixture of L-Pdots and N-Pdots that were covalently modified with quencher-labeled DNAs, respectively, to recognize the corresponding miRNAs. Upon the addition of duplex-specific nuclease, the DNAs hybridized with miRNAs were digested to release the quenchers and miRNAs, which led to the ECL recovery of Pdots and target-cyclic signal amplification. By imaging the array at +0.6 and +1.0 V and using miRNA-21 and miRNA-205 as the analytes, the blue and red channel images could be extracted to quantify these miRNAs with detection limits of 2.5 and 3.1 pM, respectively. This work provides a new family member of potential- or color-resolved ECL emitters and successfully realizes the simultaneous and high-throughput sensing of multiplex miRNAs.