Dual-Cascade Activated DNAzyme Nanoreactor within a Zn-Based MOF for Mitochondrial Gene Regulation

Gene therapy targeting specific organelle genes crucial for cancer cell survival provides a promising strategy for hepatocellular carcinoma (HCC) therapy. The integration of metal-organic framework nanostructures with catalytic nucleic acids provides a promising route toward precision gene therapy. Herein, we report a dual-cascade DNAzyme nanoreactor constructed from the zeolitic imidazolate framework-90 (ZIF-90), which simultaneously serves as a protective host and a zinc ion reservoir. The framework encapsulates an EGR-1-targeting DNAzyme and is further engineered with lignin, N-acetylgalactosamine, and triphenylphosphonium ligands to achieve cascade targeting of HCC cells and their mitochondria. Within the mitochondrial microenvironment, characterized by mildly alkaline pH and elevated ATP concentration, the lignin shell and MOF scaffold undergo programmed disassembly. This cascade process triggers the release of DNAzyme together with Zn²⁺ cofactors, thereby initiating site-specific catalytic cleavage of target mRNA. Structural characterization confirmed the crystalline integrity, functionalization sequence, and stimuli-responsive degradation of the nanoreactor, while biological assays demonstrated efficient mitochondrial localization and selective gene silencing. In vivo studies further revealed pronounced tumor suppression with minimal systemic toxicity. This work highlights the potential of ZIF-90 as chemically programmable carriers that combine metal-organic framework with DNAzyme for organelle-level therapeutic intervention.