Iron-Palladium Decorated Carbon Nanotubes Achieve Radiosensitization via Reactive Oxygen Species Burst

Radiotherapy is recommended as a modality for cancer treatment in clinic. However, cancerous cells were resistant to therapeutic irradiation due to its DNA repair. In this work, single-walled carbon nanotubes with unique physical properties of hollow structures and high specific surface area were introduced as carrier for iron-palladium (FePd) to obtain iron-palladium decorated carbon nanotubes (FePd@CNTs). On one hand, FePd nanoparticles possess significant ability in radiosensitization as previously reported. On the other hand, carbon nanotubes offer higher efficiency in crossing biological barriers, inducing the accumulation and retention of FePd nanoparticles within tumor tissue. In order to verify the radiosensitization effect of FePd@CNTs, both in vitro and in vivo experiments were conducted. These experiments showed that the FePd@CNTs exhibited remarkably better radiosensitization effect and more obvious accumulation than FePd NPs, suggesting a potential of FePd@CNTs in radiosensitization.

Endogenous reactive oxygen species burst induced and spatiotemporally controlled multiple drug release by traceable nanoparticles for enhancing antitumor efficacy

Reactive oxygen species (ROS) are not only used as a therapeutic reagent in chemodynamic therapy (CDT), to stimulate the release of drugs, they can also be used to achieve a combined effect of CDT and chemotherapy to enhance anticancer effects.

Piezo-Photocatalytic Effect Mediating Reactive Oxygen Species Burst for Cancer Catalytic Therapy

A piezo-photocatalytic therapy based on thermal treated natural sphalerite nanosheets (NSH700 NSs) heterojunction are applied to efficiently induce intracellular ROS burst and apoptosis of cancer cells. Upon ultrasound and laser...

Oxalic Acid Metabolism Contributes to Full Virulence and Pycnidial Development in the Poplar Canker Fungus Cytospora chrysosperma

Poplar Cytospora canker, which is mainly caused by Cytospora chrysosperma, is one of the most destructive and widespread tree diseases worldwide. Although oxalic acid (OA) is demonstrated as an important virulence determinant in several necrotrophic fungi, specific functions of OA during pathogenesis remain controversial. Here, we identified three genes (CcOah, CcOdc1, and CcOdc2) directly involved in OA biosynthesis and catabolism in C. chrysosperma. We demonstrated that CcOah is required for OA biogenesis. All three genes were found to be highly upregulated during early infection stages of the poplar stem. The deletion of any of the three genes led to an obvious reduction of pycnidial production but no abnormality of hyphal growth and morphology. Furthermore, the individual deletion strain exhibited significantly limited lesion sizes on poplar twigs and leaves. Exogenous application of OA or citric acid can complement the virulence defects of ΔCcOah and ΔCcOdc1 strains. We further found that the ΔCcOah strain strongly promoted reactive oxygen species burst of poplar leaves during infection. Finally, induced secretion of OA was observed by monitoring color change of the plates after poplar stem extracts were added in the cultures; however, we failed to quantify OA concentration by high-performance liquid chromatography. Taken together, the present results provide insights into the function of OA acting as an important virulence factor of C. chrysosperma.

Correction: A mitochondria-targeted nanoradiosensitizer activating reactive oxygen species burst for enhanced radiation therapy

Correction for ‘A mitochondria-targeted nanoradiosensitizer activating reactive oxygen species burst for enhanced radiation therapy’ by Na Li et al., Chem. Sci., 2018, 9, 3159–3164, DOI: 10.1039/C7SC04458E.

Author Correction: Mitochondria-specific drug release and reactive oxygen species burst induced by polyprodrug nanoreactors can enhance chemotherapy

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Phevamine A, a small molecule that suppresses plant immune responses

Bacterial plant pathogens cause significant crop damage worldwide. They invade plant cells by producing a variety of virulence factors, including small-molecule toxins and phytohormone mimics. Virulence of the model pathogen Pseudomonas syringae pv. tomato DC3000 (Pto) is regulated in part by the sigma factor HrpL. Our study of the HrpL regulon identified an uncharacterized, three-gene operon in Pto that is controlled by HrpL and related to the Erwinia hrp-associated systemic virulence (hsv) operon. Here, we demonstrate that the hsv operon contributes to the virulence of Pto on Arabidopsis thaliana and suppresses bacteria-induced immune responses. We show that the hsv-encoded enzymes in Pto synthesize a small molecule, phevamine A. This molecule consists of l-phenylalanine, l-valine, and a modified spermidine, and is different from known small molecules produced by phytopathogens. We show that phevamine A suppresses a potentiation effect of spermidine and l-arginine on the reactive oxygen species burst generated upon recognition of bacterial flagellin. The hsv operon is found in the genomes of divergent bacterial genera, including ∼37% of P. syringae genomes, suggesting that phevamine A is a widely distributed virulence factor in phytopathogens. Our work identifies a small-molecule virulence factor and reveals a mechanism by which bacterial pathogens overcome plant defense. This work highlights the power of omics approaches in identifying important small molecules in bacteria–host interactions.