Dual drug-loaded metal–phenolic networks for targeted magnetic resonance imaging and synergistic chemo–chemodynamic therapy of breast cancer

The development of nanomedicines with simplified compositions and synergistic theranostic functionalities remains a great challenge. Herein, we develop a simple method to integrate both atovaquone (ATO, a mitochondrial inhibitor) and cisplatin within tannic acid (TA)-iron (Fe) networks coated with hyaluronic acid (HA) for targeted magnetic resonance (MR) imaging-guided chemo-chemodynamic synergistic therapy. The formed TFP@ATO-HA displayed good colloidal stability with a mean size of 95.5 nm, which could accumulate at tumor sites after circulation and be specifically taken up by metastatic 4T1 cells overexpressing CD44 receptors. In the tumor microenvironment, TFP@ATO-HA could release ATO/cisplatin and Fe³⁺ in a pH-responsive manner, deplete glutathione, and generate reactive oxygen species with endogenous H₂O₂ for chemodynamic therapy (CDT). Additionally, ATO could enhance chemotherapeutic efficacy by inhibiting mitochondrial respiration, relieving hypoxia, and amplifying the CDT effect by decreasing intracellular pH and elevating Fenton reaction efficiency. In vivo experiments demonstrated that TFP@ATO-HA could effectively inhibit tumor growth and suppress lung metastases without obvious systemic toxicity. Furthermore, TFP@ATO-HA exhibited a r₁ relaxivity of 2.6 mM^-1 s^-1 and targeted MR imaging of 4T1 tumors. Dual drug-loaded metal-phenolic networks can be easily prepared and act as effective theranostic nanoplatforms for targeted MR imaging and synergistic chemo-chemodynamic therapy.