A novel and highly sensitive method for detection of microRNA (miRNA) was developed by integration of T7 exonuclease-triggered amplification and cationic conjugated polymer (CCP) biosensing. First, a fluorescein-labeled probe was designed with the complementary sequence to the target miRNA. When target miRNA was absent in the solution, the fluorescence probe interacted with CCP through the strong electrostatic interactions, leading to the highly efficient fluorescence resonance energy transfer (FRET) from CCP to fluorescein. In the presence of target miRNA, the probe hybridized with the miRNA to form DNA/miRNA duplex hybrids. Then, T7 exonuclease digested cyclically the fluorescence probes in hybrids and triggered the enzyme amplification reaction, generating a large number of single nucleotides. Owing to the weak electrostatic interaction between CCP and the single nucleotide, the FRET from CCP to fluorescein would not take place, which effectively reduced the background and significantly enhanced the sensitivity and the dynamic range of miRNA detection. The linear range of the assay was 0.2–100 pM and the detection limit 0.08 pM was 58 times lower than that of the endonuclease-based assay. The method is simple, cost-effective, and with no need for the sophisticated instrument, and has broad application prospects for miRNA detection and early diagnosis.

通过整合T7核酸外切酶触发的扩增和阳离子共轭聚合物（CCP）的生物传感，开发了一种检测microRNA（miRNA）的新颖且高度灵敏的方法。首先，设计了荧光素标记的探针，该探针具有与靶标miRNA的互补序列。当溶液中不存在目标miRNA时，荧光探针会通过强的静电相互作用与CCP相互作用，从而导致从CCP到荧光素的高效荧光共振能量转移（FRET）。在存在靶标miRNA的情况下，探针与miRNA杂交形成DNA / miRNA双链体杂交体。然后，T7核酸外切酶循环消化杂交物中的荧光探针并引发酶扩增反应，生成大量的单核苷酸。由于CCP与单核苷酸之间的弱静电相互作用，因此不会发生CCP与荧光素之间的FRET，从而有效地减少了背景，并显着提高了miRNA检测的灵敏度和动态范围。测定的线性范围为0.2–100 pM，检出限为0.08 pM，比基于核酸内切酶的测定低58倍。该方法简便，经济，不需要复杂的仪器，在miRNA检测和早期诊断方面具有广阔的应用前景。08 pM比基于核酸内切酶的测定低58倍。该方法简便，经济，不需要复杂的仪器，在miRNA检测和早期诊断方面具有广阔的应用前景。08 pM比基于核酸内切酶的测定低58倍。该方法简便，经济，不需要复杂的仪器，在miRNA检测和早期诊断方面具有广阔的应用前景。