Catalytic Amplification-Mediated Single-Nanotag Assembly for Sensitive Detection of Circulating microRNAs

Circulating microRNAs are promising cancer biomarkers, which are characterized by low abundance, small size, and high sequence homology. As such, enzyme-assisted amplification strategies are often indispensable, which sometimes complicates their detection. Herein, a catalytic enzyme-free single-nanotag assembly strategy is developed for the sensitive quantification of miR-373, thanks to the synergistic amplification effect of catalytic hairpin assembly and single-nanoparticle analysis. Elemental mass spectrometric counting of liberated single nanotags provides a low detection limit of 6.0 amol for miR-373, with validation in human serum and cell lysates.