A MnO2 nanosheet-mediated photo-controlled DNAzyme for intracellular miRNA cleavage to suppress cell growth

Certain miRNAs, called oncomiRs, play a causal role in the onset and maintenance of cancer when overexpressed, thus, representing a potential new class of targets for therapeutic intervention. RNA-cleaving DNAzymes, mainly aimed at mRNA, have shown potential as therapeutic agents for various diseases. However, it's rarely reported that a DNAzyme was used for intracellular miRNA cleavage to suppress cell growth. Herein, we have developed a MnO₂ nanosheet-mediated photo-controlled DNAzyme (NPD) for intracellular miRNA cleavage to suppress cell growth. MnO₂ nanosheets adsorb photocaged DNAzymes, protect them from enzymatic digestion, and efficiently deliver them into cells. In the presence of intracellular glutathione (GSH), MnO₂ nanosheets are reduced to Mn²⁺ ions, which serve as cofactors of the 8-17 DNAzyme for miRNA cleavage. Once the DNAzyme is activated by light, it can cyclically cleave endogenous miR-21 inside cells, which would suppress cancer cell migration and invasion, and finally induce cancer cell apoptosis.