A tumor microenvironment responsive nanoplatform with oxidative stress amplification for effective MRI-based visual tumor ferroptosis.

As a promising new form of non-apoptotic regulated cell death, ferroptosis has potential as an effective supplement to apoptosis-based cancer treatments. However, high intracellular glutathione (GSH) levels and insufficient hydrogen peroxide (HO) in the tumor limit the efficacy of ferroptosis. Here, we designed a theranostic nanoplatform, named FCS/GCS, by incorporating amphiphilic polymer skeletal (P-SS-D), cinnamaldehyde prodrug (CA-OH) and iron ions (Fe)/gadolinium ions (Gd) via chelation reactions between Fe/Gd and polyphenols. When delivered in the tumor microenvironment with high GSH level, the nanoparticles are depolymerized by the poly(disulfide) backbone of P-SS-D. The activated CA consumes the GSH and elevates intracellular HO, followed by a high level of Fenton reaction to generate abundant •OH levels. The generation of reactive oxygen species (ROS) further accelerates CA activation. The GSH consumption by disulfide, CA and Fe, downregulates GPX4 and generates •OH, which accelerate lipid peroxides (LPO) accumulation and consequently enhances ferroptosis. Additionally, the released Gd may serve as a contrast agent for tumor-specific T-weighted magnetic resonance imaging (MRI). Thus, the rationally designed FCS/GCS system is a promising strategy for effective MRI-based visual ferroptosis therapy. STATEMENT OF SIGNIFICANCE: Ferroptosis is a new form of non-apoptotic regulated cell death and has potential as an effective supplement to apoptosis-based cancer treatment. However, the efficiency of ferroptosis is limited by excessive glutathione level and insufficient hydrogen peroxide level in tumor site. In this study, we fabricate a theranostic nanoplatform (FCS/GCS) to amplify oxidation stress in tumor site for effective ferroptosis-based cancer treatment, and tumor specific magnetic resonance imaging is introduced for supervision. Our nanoplatform may provide a promising strategy for MRI-based visual ferroptosis therapy with high specificity and efficiency.