Ultrasensitive Detection of MicroRNA in Tumor Cells and Tissues via Continuous Assembly of DNA Probe.

Nucleic acids have been engineered to participate in a wide variety of tasks. Among them, the enzyme-free amplification modes, enzyme-free DNA circuits (EFDCs), and hybridization chain reactions (HCRs) have been widely applied in a series of studies of bioanalysis. We demonstrated here an ultrasensitive hairpin probe-based circulation for continuous assemble of DNA probe. This strategy improved the analyte stability-dependent amplification efficiency of EFDC and signal enhancement without being limited by the analyte's initial concentration, and it was used to produce a novel microRNA (miRNA) trace analysis assay with ultrasensitive amplification properties. Through the detection of standard miRNA substances, 1 amol-level sensitivity and satisfactory specificity were achieved. Compared with EFDCs and HCRs, the sensitivity of ultrasensitive hairpin probe-based circulation was higher by 3 or 4 orders of magnitude. Furthermore, the excellent performance of this platform was also demonstrated in the detection of miRNAs in tumor cells. The sensitivities for the detection of miRNAs in HepG2, A549 and MCF-7 tumor cells were 10, 10, and 100 cells, respectively. In addition, a high detection rate of 83% was achieved for tumor tissues. Thus, this ultrasensitive hairpin probe-based circulation possesses the potential to be a technological innovation in the field of tumor diagnosis.