External radiotherapy is extensively used in clinic to destruct tumors by locally applied ionizing‐radiation beams. However, the efficacy of radiotherapy is usually limited by tumor hypoxia‐associated radiation resistance. Moreover, as a local treatment technique, radiotherapy can hardly control tumor metastases, the major cause of cancer death. Herein, core–shell nanoparticles based poly(lactic‐co‐glycolic) acid (PLGA) are fabricate, by encapsulating water‐soluble catalase (Cat), an enzyme that can decompose H2O2 to generate O2, inside the inner core, and loading hydrophobic imiquimod (R837), a Toll‐like‐receptor‐7 agonist, within the PLGA shell. The formed PLGA‐R837@Cat nanoparticles can greatly enhance radiotherapy efficacy by relieving the tumor hypoxia and modulating the immune‐suppressive tumor microenvironment. The tumor‐associated antigens generated postradiotherapy‐induced immunogenic cell death in the presence of such R837‐loaded adjuvant nanoparticles will induce strong antitumor immune responses, which together with cytotoxic T‐lymphocyte associated protein 4 (CTLA‐4) checkpoint blockade will be able to effectively inhibit tumor metastases by a strong abscopal effect. Moreover, a long term immunological memory effect to protect mice from tumor rechallenging is observed post such treatment. This work thus presents a unique nanomedicine approach as a next‐generation radiotherapy strategy to enable synergistic whole‐body therapeutic responses after local treatment, greatly promising for clinical translation.

Abnormal H 2 O 2 levels are closely related to many diseases, including inflammation and cancers. Herein, we simultaneously load HRP and its substrate, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), into liposomal nanoparticles, obtaining a Lipo@HRP&ABTS optical nanoprobe for in vivo H 2 O 2 -responsive chromogenic assay with great specificity and sensitivity. In the presence of H 2 O 2 , colorless ABTS would be converted by HRP into the oxidized form with strong near-infrared (NIR) absorbance, enabling photoacoustic detection of H 2 O 2 down to submicromolar concentrations. Using Lipo@HRP&ABTS as an H 2 O 2 -responsive nanoprobe, we could accurately detect the inflammation processes induced by LPS or bacterial infection in which H 2 O 2 is generated. Meanwhile, upon systemic administration of this nanoprobe we realize in vivo photoacoustic imaging of small s.c. tumors (∼2 mm in size) as well as orthotopic brain gliomas, by detecting H 2 O 2 produced by tumor cells. Interestingly, local injection of Lipo@HRP&ABTS further enables differentiation of metastatic lymph nodes from those nonmetastatic ones, based on their difference in H 2 O 2 contents. Moreover, using the H 2 O 2 -dependent strong NIR absorbance of Lipo@HRP&ABTS, tumorspecific photothermal therapy is also achieved. This work thus develops a sensitive H 2 O 2 -responsive optical nanoprobe useful not only for in vivo detection of inflammation but also for tumor-specific theranostic applications.hydrogen peroxide | inflammation | tumor | photoacoustic imaging | photothermal therapy

Ultrasound (US)-triggered sonodynamic therapy (SDT) that enables noninvasive treatment of large internal tumors has attracted widespread interest. For improvement in the therapeutic responses to SDT, more effective and stable sonosensitizers are still required. Herein, ultrafine titanium monoxide nanorods (TiO1+x NRs) with greatly improved sono-sensitization and Fenton-like catalytic activity were fabricated and used for enhanced SDT. TiO1+x NRs with an ultrafine rodlike structure were successfully prepared and then modified with polyethylene glycol (PEG). Compared to the conventional sonosensitizer, TiO2 nanoparticles, the PEG–TiO1+x NRs resulted in much more efficient US-induced generation of reactive oxygen species (ROS) because of the oxygen-deficient structure of TiO1+x NR, which predominantly serves as the charge trap to limit the recombination of US-triggered electron–hole pairs. Interestingly, PEG–TiO1+x NRs also exhibit horseradish-peroxidase-like nanozyme activity and can produce hydroxyl radicals (•OH) from endogenous H2O2 in the tumor to enable chemodynamic therapy (CDT). Because of their efficient passive retention in tumors post intravenous injection, PEG–TiO1+x NRs can be used as a sonosensitizer and CDT agent for highly effective tumor ablation under US treatment. In addition, no significant long-term toxicity of PEG–TiO1+x NRs was found for the treated mice. This work highlights a new type of titanium-based nanostructure with great performance for tumor SDT.

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Development of multifunctional stimuli-responsive nanomedicine is appealing for effective cancer treatment. Herein, we utilize the biocompatible CaCO 3 nanoparticles as the template to guide the formation of pH-dissociable hollow coordination nanostructures, in which meso-tetra-(4-carboxyphenyl)porphine (TCPP), a sonosensitizer, acts as the organic bridging molecule and ferric ion serves as the metallic center. L-buthionine sulfoximine (BSO), an inhibitor for glutathione (GSH) biosynthesis, can be simultaneously loaded during the preparation of TCPP-Fe@CaCO 3 , obtaining BSO-TCPP-Fe@CaCO 3 with pH-responsive dissociation to endow fast release of Ca 2+ and BSO under an acidic tumor microenvironment. Such BSO-TCPP-Fe@CaCO 3 confers synergistic oxidative stress amplification via intracellular Ca 2+ -overloading-induced mitochondria damage, BSO-mediated GSH depletion, and TCPP-mediated sonodynamic therapy (SDT), leading to remarkable cell death. Consequently, tumors on the mice treated with BSO-TCPP-Fe@-CaCO 3 administration and subsequent ultrasound exposure are effectively suppressed. Our work thus highlights a facile strategy to prepare pH-dissociable nanomedicine for effective SDT treatment of tumors via triple amplification of tumor oxidative stress.

Tumor microenvironment (TME)-mediated cancer therapy, such as chemodynamic therapy (CDT) based on Fenton reaction, has attracted extensive attention in recent years. However, efficient Fenton reactions usually require stringent reaction conditions (low pH value and sufficient H 2 O 2 ). Therefore, there is an urgent need to improve the efficiency of Fenton reaction within the tumor for enhanced CDT in cancer treatment. Herein, Cu 2 Se hollow nanocubes (HNCs) are successfully prepared via an anion exchange method using Cu 2 O nanocubes (NCs) as the template. This method is also successfully used to synthesize Cu 2 S or CuSSe HNCs with the similar structure. By tuning the reaction time in the process of transforming Cu 2 O NCs into Cu 2 Se HNCs, Cu 2 Se HNCs with optimized performances in high NIR II photothermal conversion efficiency (50.89%) and good Fenton-like properties are obtained. After surface coating, PEGylated Cu 2 Se HNCs show good water dispersibility and biocompatibility. Importantly, in vitro and in vivo experiments demonstrate the significant synergistic effect of combining photothermal therapy (PTT) and CDT based on PEG-Cu 2 Se HNCs, achieving greatly enhanced efficacy than that obtained by PTT or CDT alone. Moreover, such PEG-Cu 2 Se HNCs appear to be rather safe for treated animals without noticeable long-term toxicity.

Efficient electrocatalysts for the oxygen reduction reaction (ORR) play a critical role in the performance of fuel cells and metal-air batteries. In this study, we report a facile synthesis of phosphorus (P)-doped porous carbon as a highly active electrocatalyst for the ORR. Phosphorus-doped porous carbon was prepared by simultaneous doping and activation of carbon with phosphoric acid (H 3 PO 4 ) in the presence of Co. Both phosphorus and cobalt were found to play significant roles in improving the catalytic activity of carbon for the ORR. The as-prepared phosphorus-doped porous carbon exhibited considerable catalytic activity for the ORR as evidenced by rotating ring-disk electrode studies. At the same mass loading, the Tafel slope of phosphorus-doped porous carbon electrocatalysts is comparable to that of the commercial Pt/C catalysts (20 wt% Pt on Vulcan XC-72, Johnson Matthey) with stability superior to Pt/C in alkaline solutions.