Electrochemical detection of zeptomolar miRNA using an RNA-triggered Cu2+ reduction method

Abstract

The development of ultrasensitive, selective, simple, and rapid microRNA (miRNA) detection strategies has been crucial because of their use as probable biomarkers for diagnosing human diseases. We herein described a label- and wash-free electrochemical miRNA detection method with zeptomolar sensitivity, which relies on target miRNA-induced reduction of Cu2+ and consequential changes in electrochemical signals generated from the remaining Cu2+. Target miRNA was successfully identified with a detection limit of 33.2 zM based on this simple principle. The synergistic combination of miRNA recycling and Cu2+ reduction reactions contributed to this ultrasensitivity. Moreover, the developed electrochemical sensing method exhibited label- and wash-free detection of miRNA, showing potential applicability as a point-of-care testing system. Furthermore, the practical application of the designed technique was demonstrated by reliably detecting the target miRNA in the total RNA samples extracted from various cancer cell lines. We also believe that the conceived approach could be widely used to detect not only miRNAs but also diverse biomolecules by simply replacing the detection probe.