The Acid-Stimulated\nSelf-Assembled DNA Nanonetwork\nfor Sensitive Detection and Living Cancer Cell Imaging of MicroRNA-221

Herein, a novel functional DNA structure, acid-stimulated\nself-assembly\nDNA nanonetwork (ASDN), was proposed for miRNA-221 sensitive detection\nand high-resolution living cancer cell imaging. Significantly, the\nself-assembly of ASDN only occurred in the acidic extracellular environment\nof cancer cells, which could be endocytosed by cancer cells to eliminate\nthe interference of noncancer cells and deliver the ASDN into cancer\ncells. Subsequently, endogenous miRNA-221 could trigger the catalytic\nhairpin assembly within ASDN, resulting in the separation of the fluorophore\nCy5 and the quencher BHQ2 to recover the substantial Cy5 fluorescence\nsignals, thus achieving signal amplification for sensitive detection\nof miRNA-221 with a detection limit of 5.5 pM, as well as facilitating\nhigh-resolution and low-background imaging of miRNA-221 in cancer\ncells. In consequence, this strategy provides an innovative DNA nanonetwork\nto distinguish cancer cells from other cells for sensitive detection\nof biomarkers, offering a meaningful reference for the application\nof DNA nanostructure self-assembly technology in relevant fundamental\nresearch and disease diagnosis.