Dynamic Iron Catalysis on Quantum Dots Enables Ultrasound-Controlled Multimodal Cancer Therapy
The tumor microenvironment (TME) is characterized by elevated H2O2 levels and hypoxia, posing significant challenges to effective cancer treatment. Chemodynamic therapy (CDT) exploits these conditions to generate cytotoxic hydroxyl radicals via Fenton reactions, yet its efficacy as a monotherapy is limited. Sonodynamic therapy (SDT) offers deep-tissue ROS generation under ultrasound (US) but is oxygen-dependent. Immunotherapy can modulate systemic immune responses but often suffers from low response rates. Here, we highlight a recent breakthrough published in Nature Nanotechnology by Prof. Jiatao Zhang and colleagues, who engineered a multifunctional quantum dot system (FAQD) integrating CDT, SDT, and immunotherapy through atomically dispersed iron and selenium chemistry. The FAQD comprises zinc selenide quantum dots with Ag doping and Fe decoration, synthesized via a three-step method. Structural analyses (HAADF-STEM, XRD, XPS, EXAFS) confirmed a quasi-single-crystalline structure with atomically dispersed Fe(III) and Ag(I). Optimal Ag:Zn ratio (5:100) maximized singlet oxygen yield under US. In vitro, FAQD-1 (with MMP-cleavable PEG) exhibited negligible cytotoxicity without US, but under US and H2O2, induced substantial ROS production, mitochondrial impairment, and apoptosis in HeLa cells. In vivo, FAQD-1 with US achieved complete suppression of primary and abscopal tumors within two weeks, eliciting robust systemic immune responses (increased CD8+ and CD4+ T cells, reduced Tregs, elevated IL-2 levels). This work demonstrates a synergistic trimodal nanoplatform with precise spatiotemporal control, offering a promising strategy for cancer therapy.