A Modular Endogenous-Responsive DNA Nanosponge for Cancer-Selective RNA Demethylase Imaging and Concurrent...

RNA demethylase plays a crucial role in the dynamic regulation of m⁶A modification and has been identified as promising biomarker and therapeutic target. However, real-time monitoring of its activity in living cells remains challenging due to poor probe stability, and lack of tumor selectivity. Herein, we develop a cancer-targeting, endogenous-activated DNA nanosponge (DNS) platform for cancer-selective FTO imaging. The DNS is constructed via rolling circle amplification and loaded with FTO-responsive DNAzyme probes (FDz) and photosensitizer zinc phthalocyanine (ZnPc) to form FDz-ZnPc@DNS. The FDz are initially silenced by m⁶A modification and conjugated to DNS via glutathione (GSH)-cleavable disulfide linkage. Upon folate receptor-mediated internalization of FDz-ZnPc@DNS into cancer cells, intracellular GSH triggers the release of FDz. Subsequent FTO-mediated demethylation reactivates the DNAzyme, leading to amplified fluorescence recovery for FTO imaging. Concurrently, under 660 nm laser illumination, ZnPc generates cytotoxic singlet oxygen to destroy cancer cells/tissues via photodynamic therapy. Both in vitro and in vivo studies validate the feasibility of this nanoplatform for cancer-selective imaging and effective treatment. This work presents a robust and versatile nanoplatform that merges targeted delivery and endogenous activation for precise cancer imaging and therapy, with the potential for adaptation to diverse sensing and therapeutic payloads through modular reprogramming.