Real-time imaging of multiple low-abundance
microRNAs (
miRNAs) simultaneously in living cells with high sensitivity is of vital importance for accurate
cancer clinical diagnosis and prognosis studies. Maintaining stability of nanoprobes resistant to
enzyme degradation and enabling effective signal amplification is highly needed for in vivo imaging studies. Herein, a rationally designed one-pot assembled multicolor tetrahedral
DNA frameworks (TDFs) by encoding multicomponent
nucleic acid enzymes (MNAzymes) was developed for signal-amplified multiple
miRNAs imaging in living cells with high sensitivity and selectivity. TDFs could enter cells via self-delivery with good biocompatibility and stability. Two kinds of MNAzymes specific for miRNA-21 and miRNA-155 with
fluorescein labeling were encoded in the structure of TDFs respectively through one-step thermal annealing. In the intracellular environment, the TDFs could be specifically bound with its specific
miRNA target and form an active
DNAzyme structure. The cleavage of the active site would trigger the release of target
miRNA and circular fluorescence signal amplification, which enabled accurate diagnosis on
miRNA identifications of different cell lines with high sensitivity. Meanwhile, with the specific
AS1411 aptamer targeting for
nucleolin overexpressed on the surface of the
carcinoma cells, this well-designed TDFs nanoprobe exhibited good discrimination between
cancer cells and normal cells. The strategy provides an efficient tool for understanding the biological function of
miRNAs in
cancer pathogenesis and therapeutic applications.