Self-Assembly of Multifunctional DNA Nanohydrogels with Tumor Microenvironment-Responsive Cascade Reactions for Cooperative Cancer Therapy.

A DNA structure-based nanoreactor has emerged as a promising biomaterial for antitumor therapy with its intrinsic biodegradability, biocompatibility, and tunable multifunctionality. Herein, the intelligent DNA nanohydrogel was reported to target cancer cells, control the size, be pH-responsive, and be loaded with glucose oxidase (GOx). Two kinds of X-shaped DNA monomers and DNA linkers were assembled to form a DNA nanohydrogel by hybridization. GOx was successfully encapsulated in the DNA nanohydrogel. The DNA linker was designed with i-motif sequences and modified with ferrocene (Fc). The i-motif-like quadruplex structures were formed in acidic tumor microenvironments, resulting in the disassembly of the DNA nanohydrogel to release GOx. The GOx could oxidize the intratumoral glucose to produce gluconic acid and H2O2. The generated H2O2 was catalyzed by Fc to induce toxic hydroxyl radicals (•OH), which could effectively kill cancer cells. Both the in vitro and the in vivo results demonstrated that the multifunctional DNA nanohydrogel had high-efficiency tumor suppression through combined chemodynamic and starvation cancer therapies.