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Abstract In this work, a tumor microenvironment (TME)-responsive biodegradable MnSiO 3 @Fe 3 O 4 nanoplatform for dual-mode magnetic resonance imaging (MRI)-guided combinatorial cancer therapy was constructed. Fe 3 O 4 nanoparticles decorated on the surface of MnSiO 3 could effectively obstruct the pores of MnSiO 3 and reduce the leakage of anticancer drugs under physiological conditions. The structure of the nanoplatform was broken under the weakly acidic and high-concentration glutathione conditions in the TME, resulting in the separation of the Fe 3 O 4 nanoparticles from the nanoplatform and rapid drug release. In addition, the exfoliated Fe 3 O 4 and released Mn2+ can help reduce the interference between their T 1 and T 2 contrast abilities, resulting in dual-mode MRI contrast enhancement. Furthermore, during the exfoliation process of the Fe 3 O 4 nanocrystals, the catalytic activity of the Fe 3 O 4 nanocrystals toward a Fenton-like reaction within cancer cells could be improved because of the increase in specific surface area, which led to the generation of highly toxic hydroxyl radicals and induced HeLa cell apoptosis. The nanoplatform also displayed excellent T 1 -T 2 dual-mode MRI contrast enhancement and anticancer activity in vivo with reduced systemic toxicity. Thus, this multifunctional nanoplatform could be a potential nanotheranostic for dual-mode MRI-guided combinatorial cancer therapy. Graphical abstract A multifunctional MnSiO 3 @Fe 3 O 4 nanoplatform is constructed by decorating Fe 3 O 4 nanoparticles on the surface of MnSiO 3 , followed by amination and grafting PEG on the surface and subsequently loading cisplatin into the nanoplatform. This well-engineered nanoplatform with tumor microenvironment-responsive biodegradable ability displays outstanding dual-mode MRI-guided combinatorial catalytic nanotherapeutics (the generation of ·OH) and chemotherapy for cancer treatment. Image 1 [ABSTRACT FROM AUTHOR]

Chemodynamic therapy (CDT) was widely exploited for cancer therapy and expected to replace traditional anticancer drug therapies. Generally, CDT needs to combine with extra therapeutic methods for obtaining the optimal therapeutic efficacy of cancer. Herein, a multifunctional theranostic platform combing CDT with limotherapy was developed via nanoselenium (nano-Se)-coated manganese carbonate-deposited iron oxide nanoparticle (MCDION-Se). MCDION-Se could release abundant of Mn2+ ions that catalyzed H 2 O 2 into hydroxyl radicals (· OH) via a Fenton-like reaction, effectively inducing the apoptosis of cancer cells. Besides, nano-Se coated onto MCDION-Se also dramatically activated superoxide dismutase (SOD) and promoted the generation of superoxide anion radicals (SOARs) in tumor tissue. Subsequently, a high content of H 2 O 2 was produced via SOD catalysis of SOARs, further enhancing CDT efficiency. Meanwhile, the nano-Se and Mn2+ ions inhibited the generation of adenosine triphosphate (ATP), thus starving cancer cells. In addition, in vitro and in vivo experiments showed that MCDION-Se could effectively enhance the contrast of tumor tissue and improve the quality of magnetic resonance imaging (MRI). Overall, this work provided a nanoplatform that combined CDT with limotherapy for cancer therapy and simultaneously utilized MRI for monitoring the treatment of tumors. A pH-responsive free-drug theranostic platform (MCDION-Se) combined chemodynamic therapy with limotherapy was developed for MRI-guided tumor therapy. Image 1 [ABSTRACT FROM AUTHOR]