Enzyme-free isothermal target-recycled amplification combined with PAGE for direct detection of microRNA-21

Abstract

MicroRNA-21 (miR-21) has been regarded as a kind of potential biomarker in several types of cancers. Herein, in this study, a simple, sensitive and cost-effective miR-21 approach was developed utilizing the isothermal target-recycled enzyme-free amplification strategy and polyacrylamide gel electrophoresis (PAGE). In the target-recycled enzyme-free amplification strategy, two rational designed hairpin probes (HPs, HP1 and HP2) can form into HP1-HP2 duplex in the presence of miR-21 under the isothermal condition, producing target signal in PAGE. The sensitivity and the linear range of miR-21 approach were demonstrated by the in vitro detection of miR-21, with the detection limit of 10 pM and the linear range of 50 pM to 8 nM. In particular, the contents of miR-21 in cell extractions of different cell lines were successfully detected through miR-21 approach and the relative expression was highly coincident with the results of stem-loop RT-PCR approach. In summary, the developed approach can detect miR-21 sensitively and easily.