Endogenously Activated and Self‐Reinforced DNA Lipid Nanodevice for Spatial‐Specific and High‐Contrast Imaging of MicroRNA in Cells and Animals.

Tumor‐specific microRNA (miRNA) imaging strategies are critical for investigating mechanisms associated with cancer progression; however, nonspecific signal leakage and false‐positive signaling limit their selectivity and efficiency. In this paper, an endogenously activated and self‐reinforced DNA lipid nanodevice (LND) for spatial‐specific and high‐contrast imaging of miRNAs in living cells and animals is presented. The LND is functionalized on cholesterol‐based lipid micelles (CLMs) containing smart response and self‐fueling DNA components that display redox‐activatable and autocatalytic miRNA probing activities, respectively. The LNDs are initially silenced and selectively activated using glutathione, an endogenous microenvironmental factor overexpressed in tumor cells, to prevent nonspecific signal leakage. Subsequently, an autocatalytic DNA circuit is used for tumor‐specific and high‐contrast miRNA imaging. It is demonstrated that robust CLM nanoparticles can be easily assembled from a cholesterol‐conjugated G‐rich DNA sequence by stirring in a buffered solution, enabling the LND to enter cells naturally. In addition, in vitro and in vivo data illustrate that the enhanced biostability of DNA components on the surface of LNDs can be realized for minimizing false‐positive signals, making the system ideal for miRNA imaging in living mice. This smart LND technique has great potential for precise biomedical imaging and clinical diagnosis. [ABSTRACT FROM AUTHOR]