Intracellular in situ assembly of palindromic DNA hydrogel for predicting malignant invasion and preventing tumorigenesis

DNA structural nanotechnology is of significant importance for the understanding, diagnosis and treatment of human diseases. However, few reports have examined whether DNA structural nanotechnology can be suitable for predicting the malignant invasion of tumor cells and preventing cancers. It is mainly because complex design of numerous DNA building blocks and susceptibility of nanostructures, including DNA hydrogels, to nuclease degradation as critical issues hamper the transition to clinical application. Moreover, intracellular assembly of DNA nanostructures in a very simple manner is unexplored because of technical limitations. In current study, by palindromic end-mediated cross-linking hybridization chain reaction (c-HCR), we report intracellular invasive growth of DNA hydrogel network (2 h-DNH) from only two hairpins in a sequential manner, where the palindromic fragment in DNA building blocks substantially simplifies the probe design and assembly process. Macroscopic 2 h-DNH can be visualized by naked eye and remain its structural integrity over 12-h incubation in intracellular environment. The c-HCR strategy can be used to screen intracellular miRNAs with the detection sensitivity improved by almost 2 ~ 3 orders of magnitude. Diseased cells (HeLa) are discriminated from healthy cells (HEK-293), and MCF-7 cells with different levels of miR-21 are accurately identified. Even without clinical symptoms, the invasion of malignant tumor cells is predicted by visualizing intracellular 2 h-DNH. Moreover, c-HCR-guided therapeutic intervention can hamper the tumorigenesis, indicating the great potential application in the early warning and prevention of human cancers.