Ultrasensitive detection of microRNA-21 based on electrophoresis assisted cascade chemiluminescence signal amplification for the identification of cancer cells

Rapid and accurate detection of microRNA content in cells is of great significance. Here, an ultrasensitive microchip electrophoresis (MCE) method based on cascade chemiluminescence (CL) signal amplification was developed for the detection of microRNA-21 in cells. In this method, horseradish peroxidase labeled DNA was used as a signal probe, which could induce CL signal by the reaction of luminol and H2O2. Combining with two cyclic enzyme digestion reactions by T7 exonuclease, a large number of signal probes were degraded. By using MCE-CL as a separation and detection platform, an amplified CL signal peak was achieved. The developed MCE-CL method can detect miR-21 at a concentration as low as 1.0 x 10(-15)M, which was enhanced by six orders of magnitude compared with those of conventional MCE-CL assay. This method has been applied for the detection of microRNA-21 in cell lysate, which show that there were significant differences of miR-21 among different types of cells, and the content in cancer cells was much higher than that in normal cells, which can be used for the identification of cancer cells. Therefore, the proposed method held great application potential in early diagnosis of tumor and biomedical research.