Dual-ferroptosis induction-based microneedle patches for enhanced chemodynamic/photothermal combination therapy against triple-negative breast cancer.

Triple-negative breast cancer (TNBC) remains a refractory subtype of breast cancer due to its resistance to various therapeutic strategies. In this study, we introduce a "brake-release and accelerator-pressing" approach to engineer a microneedle patch embedded with copper-doped Prussian blue nanoparticles (Cu-PB) and the ferroptosis inducer sorafenib (SRF) for raised chemodynamic (CDT)/photothermal (PTT) combination therapy against TNBC. Upon transdermal insertion, the dissolving microneedles swiftly disintegrate and facilitate the release of SRF. Under gentle external light exposure, copper ions (Cu) and iron ions (Fe) were liberated from Cu-PB. The direct chelation of Cu and the indirect suppression by SRF, collectively attenuate glutathione peroxidase 4 (GPX4) enzymatic function, destabilizing the cellular redox equilibrium (referred to as the "brake-release" strategy). The release of Cu and Fe ions instigates a Fenton/Fenton-like reaction within tumor cells, further yielding hydroxyl radicals and elevating reactive oxygen species (ROS) concentrations (referred to as the "accelerator-pressing" strategy). This overwhelming ROS accumulation, coupled with the impaired clearance of resultant lipid peroxides (LPO), ultimately triggers a robust ferroptosis cell death response. In summary, this study presents an innovative combinatorial therapeutic strategy based on dual-ferroptosis induction for TNBC, implying a promising therapeutic platform for developing ferroptosis-centered treatments for this aggressive breast cancer subtype.