A triple-amplification strategy based on the formation of peroxidase-like two-dimensional DNA/Fe3O4 networks initiated by the hybridization chain reaction for highly sensitive detection of microRNA.

A highly sensitive triple-amplification assay for the detection of microRNA (miRNA) let-7a is reported in this work. The assay relies on the formation of magnetic two-dimensional DNA/Fe3O4 nanosheet networks initiated by the target miRNA-associated hybridization chain reaction. The Fe3O4 nanosheets in the DNA/Fe3O4 networks display peroxidase-like catalytic activity towards a colorimetric reaction, thereby producing a highly sensitive signal for the quantification of let-7a. Under optimal conditions, the assay achieved a detection limit of 13 aM at a signal-to-noise ratio of 3 and a linear calibration plot between 0.05 fM and 12 nM. Successful attempts were made in the quantification of let-7a in serum samples.