EXIRM: A Novel Technique for Label-Free Detection of MicroRNA

Y. Wang, S. Xu
University of Houston, US

Keywords: microRNA, labeled free detection, magnetic sensing


MicroRNAs play important roles in cancer and other diseases. However, due to the transient nature of the MicroRNAs, it remains challenging to achieve high sensitivity and accuracy to quantify MicroRNAs. We are developing a new label-free, one-step method to detect microRNA with zeptomole sensitivity. To detect a target MicroRNA, the complementary strand is tethered to the surface that hybridizes with a DNA strand containing a single nucleotide that is different from the MicroRNA. The DNA strand is labeled with a magnetic bead which provides the read-out signal. The MicroRNA is incubated with the surface bound duplex and displaces the magnetic labeled DNA strand because of the perfectly matched duplex. The read-out signal decreases due to the detachment of the magnetic bead from the surface. The amount of the MicroRNA can be quantified with the percentage of the signal change. We have approved the principle with the cancer bio-markers, let-7a and let-7b MicroRNAs, with 400 zeptomole sensitivity. This method is a one-step, no labeling, no amplification procedure.