mRNA-Activated Multifunctional DNAzyme Nanotweezer for Intracellular mRNA Sensing and Gene Therapy.

Deoxyribozyme (DNAzyme) is regarded as a promising gene therapy drug. However, poor cellular uptake efficacy and low biological stability limit the utilization of DNAzyme in gene therapy. Here, we report a well-known programmable DNAzyme-based nanotweezer (DZNT) that provides a new strategy for the detection of TK1 mRNA and survivin mRNA-targeted gene silencing therapy. At the end of the DZNT arm, there are two functionalized single-stranded DNA and each consists of two parts: the segment complementary to TK1 mRNA and the split-DNAzyme segment. The hybridization with intracellular TK1 mRNA enables the imaging of TK1 mRNA. Meanwhile, the hybridization draws the split-DNAzyme close to each other and activates DNAzyme to cleave the survivin mRNA to realize gene silencing therapy. The results demonstrate that the DZNT nanocarrier has excellent cell penetration, good biocompatibility, and noncytotoxicity. DZNT can image intracellular biomolecule TK1 mRNA with a high contrast. Furthermore, the split-DNAzyme can efficiently cleave the survivin mRNA with the aid of TK1 mRNA commonly present in cancer cells, accordingly can selectively kill cancer cells, and has no harm to normal cells. Taken together, the multifunctional programmable DZNT provides a promising platform for the early diagnosis of tumors and gene therapy.