Isothermally sensitive detection of serum circulating miRNAs for lung cancer diagnosis.

Tumor-derived miRNAs in serum are emerging as the new noninvasive biomarkers for the diagnosis of human cancers, especially at their early stage. An ideal method with high sensitivity, excellent selectivity, a simple procedure, and small amounts of starting materials is imperative for the detection of clinic circulating miRNAs. Here, we develop a new method for isothermally sensitive detection of serum miRNAs using hairpin probe-based rolling circle amplification (HP-RCA). This method exhibits ultrahigh sensitivity toward lung cancer-related miR-486-5p with a detection limit of as low as 10 fM and a large dynamic range of 6 orders of magnitude, and it can even discriminate miR-486-5p from both miRNAs with high sequence homology and its precursors (pre-miRNAs). More importantly, this method can directly and accurately distinguish the expression of serum miR-486-5p among six nonsmall-cell lung carcinoma (NSCLC) patients and six healthy persons, holding a great potential for further applications in the clinical diagnosis of lung cancers.