Simultaneous sensitive detection and imaging of dual microRNAs through DNA tetrahedral scaffold-corbelled autonomous-motion molecular machine.

Sensitive and accurate detection and imaging of different microRNAs (miRNAs) in cancer cells hold great promise for early disease diagnosis. Herein, a DNA tetrahedral scaffold (DTS)-corbelled autonomous-motion (AM) molecular machine based fluorescent sensing platform was designed for simultaneous detection of two types of miRNAs (miRNA-21 and miRNA-155) in HeLa cells. Locking-strand-silenced DNAzymes (P:L duplex) were firstly grafted at the loop of target-analogue-embedded double-stem hairpin substrates (TDHS) of DTS, making the sensor in a "signal off" state due to the closely distance between modified fluorophores (FAM and Cy5) with the corresponding quenchers (BHQ1 and BHQ2). The detection of miRNA-21 and miRNA-155 was mainly based on the activation of locking-strand-silenced DNAzymes, cleaving hairpin DNA into single-strand DNA segments, accompanying with the release of modified fluorophores and the signal recovery (signal on). Upon the cyclical stimulation of miRNA targets in such AM molecular machine, sensitive detection of miRNA-21 and miRNA-155 was realized in this self-feedback circuit (SFC) with the detection limit down to 38.8 aM and 27.1 aM, respectively. Moreover, the analytical performance was greatly improved for miRNAs imaging in cancer cells with enhanced tumor cell recognition ability, excellent stability in virtue of DTS, indicating a potential analytical tool in early cancer diseases diagnosis.