Supramolecular Assembly of Stepped‐Persistent ROS Nanogenerator for Sustained Tumor Immunotherapy

ABSTRACT ROS‐based tumor elimination could trigger systemic antitumor immune responses. However, these strategies are fundamentally restricted by insufficient ROS generation and uncontrollable kinetic processes. Besides, tumor‐associated macrophages often reverted to an immunosuppressive phenotype due to a lack of sustained stimulation. To achieve both effective tumor eradication and sustained activation of tumor immune microenvironment, a stepped‐persistent ROS nanogenerator supramolecularly assembled multiple ROS generation modules was synthesized. G‐quadruplexes (G4s)‐DNA nanochains, functionalized with Hemin and Ce6, served as a structure‐directing agent for synthesizing polydopamine nanofibers (PDANFs). Semiquinone radicals generated during dopamine polymerization were stabilized by supramolecular interaction between G4s and polydopamine oligomers. Under NIR irradiation, PDANFs could explosively produce singlet oxygen ( ¹ O ₂ ). Moreover, the nanoconfined catalytic cascade reaction between semiquinone radicals and G4s/hemin DNAzyme leads to a dissipative generation of hydroxyl radical (•OH), extending ROS generation after NIR irradiation above an effective cytotoxic level for adequate tumor inhibition and immune activation. Additionally, PDANFs also catalyzed pathological H ₂ O ₂ to generate sub‐cytotoxic •OH, sustaining the antitumor phenotype of macrophage. The nanogenerators showed a slow reduction of ROS levels and remained above 47% and 23% after 1 and 48 h of photoactivation. Thereby, effective tumor inhibition and sustained immunoactivation were achieved. This system significantly advances ROS regulators for tumor immunotherapy.