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Doxorubicin (DOX) is a widely used first-line antitumor agent; however, acquired drug resistance and side effects have become the main challenges to effective cancer therapy. Herein, DOX is loaded into iron-rich metal–organic framework/tannic acid (TA) nanocomplex to form a tumor-targeting and acid-activatable drug delivery system (MOF/TA-DOX, MTD). Under the acidic tumor microenvironment, MTD simultaneously releases DOX and ferrous ion (Fe2+) accompanied by degradation. Apart from the chemotherapeutic effect, DOX elevates the intracellular H2O2 levels through cascade reactions, which will be beneficial to the Fenton reaction between the Fe2+ and H2O2, to persistently produce hydroxyl radicals (•OH). Thus, MTD efficiently mediates chemodynamic therapy (CDT) and remarkably enhances the sensitivity of chemotherapy. More encouragingly, the cancer cell killing efficiency of MTD is up to ~86% even at the ultralow equivalent concentration of DOX (2.26 μg/mL), while the viability of normal cells remained >88% at the same concentration of MTD. Taken together, MTD is expected to serve as drug-delivery nanoplatforms and •OH nanogenerators for improving chemo/chemodynamic synergistic therapy and reducing the toxic side effects.

Our results suggest that HF-LPLI may be an effective cancer treatment modality that both eradicates the treated primary tumors and induces an antitumor immune response via photoinactivation of respiratory chain oxidase to trigger superoxide anion burst.

Imaging-guided percutaneous microwave thermotherapy has been regarded as an important alternative nonsurgical therapeutic strategy for hepatocellular carcinoma (HCC) that provides excellent local tumor control and favorable survival benefit. However, providing a high-resolution, real-time, and noninvasive imaging technique for intraoperative guidance and controlling postoperative residual tumor recurrence are urgent needs for the clinical setting. In this study, a cisplatin (CDDP)-loaded nanocapsule (NPs@CDDP) with microwave responsive property was prepared to simultaneously serve as a contrast agent of emerging thermoacoustic imaging and a sensitizing agent of microwave thermo-chemotherapy. Accompanying the enzymolysis in the tumor microenvironment, the NPs@CDDP responsively release l-arginine (l-Arg) and CDDP. l-Arg with excellent microwave-absorbing property allowed it to serve as a thermoacoustic imaging contrast agent for accurately delineating the tumor and remarkably increasing tumor temperature under ultralow power microwave irradiation. Apart from the chemotherapeutic effect, CDDP elevated the intracellular H2O2 level through cascade reactions and further accelerated the continuous transformation of l-Arg to nitric oxide (NO), which endowed the NPs@CDDP with NO-generation capability. Notably, the high concentration of intracellular NO was proved to aggravate lipid peroxidation and greatly improved the efficacy of microwave thermo-chemotherapy. Thereby, NPs@CDDP was expected to serve as a theranostic agent integrating the functions of tumor microenvironment-responsive drug delivery system, contrast agent of thermoacoustic imaging, thermal sensitizing agent, and NO nanogenerator, which was promising to provide a potential imaging-guided therapeutic strategy for HCC.

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