Magnetic Ni/Fe layered double hydroxide nanosheets as enhancer for DNA hairpin sensitive detection of miRNA

Abstract A new non-enzyme method based on hybridization chain reaction (HCR) and colorimetric reaction catalyzed by magnetic Ni/Fe layered double hydroxide (LDH) nanosheets was developed for detection of microRNA (miRNA), let-7b . The DNA hairpins from HCR were separated and adsorbed by Ni/Fe LDH. The peroxidase-like activity of Ni/Fe LDH was found to be enhanced by the DNA hairpins on the surface. The factors, such as ratio of Ni/Fe and concentration of DNA hairpins, related to the catalytic activity were evaluated and the mechanism was discussed. The results of this new detection method for let-7b provided low limit of detection (0.36 fM), wide linear range (0.01 pM to 200 pM) with good linearity (r 2 = 0.9968). The optimized method was applied to analyze let-7b in real samples, lung cancer cells. This work demonstrated a new and cost-effective approach for efficient detection of miRNA.