Ultrasensitive Electrochemiluminescence Biosensor Based on 2D CoO Nanosheets as a Coreaction Accelerator and Highly Ordered Rolling DNA Nanomachine as a Signal Amplifier for the Detection of MicroRNA.

A novel ultrasensitive electrochemiluminescence (ECL) biosensor was constructed using two-dimensional (2D) CoO nanosheets as a novel coreaction accelerator of the luminol/HO ECL system for the detection of microRNA-21 (miRNA-21). Impressively, coreaction accelerator 2D CoO nanosheets with effective mutual conversion of the Co/Co redox pair and abundant active sites could promote the decomposition of coreactant HO to generate more superoxide anion radicals (O), which reacted with luminol for significantly enhancing ECL signals. Furthermore, the trace target miRNA-21 was transformed into a large number of G-wires through the strand displacement amplification (SDA) process to self-assemble the highly ordered rolling DNA nanomachine (HORDNM), which could tremendously improve the detection sensitivity of biosensors. Hence, on the basis of the novel luminol/HO/2D CoO nanosheet ternary ECL system, the biosensor implemented ultrasensitive detection of miRNA-21 with a detection limit as low as 4.1 aM, which provided a novel strategy to design an effective ECL emitter for ultrasensitive detection of biomarkers for early disease diagnosis.