Phytic acid-modified CeO2 as Ca2+ inhibitor for a security reversal of tumor drug resistance.

Ca2+ plays critical roles in the development of diseases, whereas existing various Ca regulation methods have been greatly restricted in their clinical applications due to their high toxicity and inefficiency. To solve this issue, with the help of Ca overexpressed tumor drug resistance model, the phytic acid (PA)-modified CeO2 nano-inhibitors have been rationally designed as an unprecedentedly safe and efficient Ca2+ inhibitor to successfully reverse tumor drug resistance through Ca2+ negative regulation strategy. Using doxorubicin (Dox) as a model chemotherapeutic drug, the Ca2+ nano-inhibitors efficiently deprived intracellular excessive free Ca2+, suppressed P-glycoprotein (P-gp) expression and significantly enhanced intracellular drug accumulation in Dox-resistant tumor cells. This Ca2+ negative regulation strategy improved the intratumoral Dox concentration by a factor of 12.4 and nearly eradicated tumors without obvious adverse effects. Besides, nanocerias as pH-regulated nanozyme greatly alleviated the adverse effects of chemotherapeutic drug on normal cells/organs and substantially improved survivals of mice. We anticipate that this safe and effective Ca2+ negative regulation strategy has potentials to conquer the pitfalls of traditional Ca inhibitors, improve therapeutic efficacy of common chemotherapeutic drugs and serves as a facile and effective treatment platform of other Ca2+ associated diseases. Electronic Supplementary Material: Supplementary material (further details of the XRD pattern of CeO2, TEM images, XPS spectra, cellular uptake study, cytotoxicity data, apoptosis study, biodistribution, and biosecurity of nanocerias in vivo, etc.) is available in the online version of this article at 10.1007/s12274-022-4069-0.

A pH-Responsive Polymer-CeO2 Hybrid to Catalytically Generate Oxidative Stress for Tumor Therapy.

Catalytic generation of reactive oxygen species has been developed as a promising methodology for tumor therapy. Direct O2•- production from intratumor oxygen exhibits exceptional tumor therapeutic efficacy. Herein, this therapy strategy is demonstrated by a pH-responsive hybrid of porous CeO2 nanorods and sodium polystyrene sulfonate that delivers high oxidative activity for O2•- generation within acidic tumor microenvironments for chemodynamic therapy and only limited oxidative activity in neutral media to limit damage to healthy organs. The hydrated polymer-nanorod hybrids with large hydrodynamic diameters form nanoreactors that locally trap oxygen and biological substrates inside and improve the charge transfer between the catalysts and substrates in the tumor microenvironment, leading to enhanced catalytic O2•- production and consequent oxidation. Together with successful in vitro and in vivo experiments, these data show that the use of hybrids provides a compelling opportunity for the delivery selective chemodynamic tumor therapy.

Preparation of Single-Crystalline AgIn5S8 Octahedrons with Exposed {111} Facets and Its Visible-Light-Responsive Photocatalytic H2 Production Activity.

Although AgIn5S8 as one kind of ternary chalcogenides has been extensively investigated due to its band-edge positions meeting the thermodynamic requirement for water photosplitting, very little attention has been focused on the crystallinity and facet effects of AgIn5S8 on its photocatalytic activity. Herein, a facile hydrothermal route was developed to fabricate regular single-crystalline AgIn5S8 octahedrons with only {111} facets exposed. Also, the effects of the hydrothermal reaction conditions on the composition, crystal phase, crystallinity, and morphology of the obtained AgxInyS(x+3y/2) products (hereafter denoted as AIS-x, where x represents the pH value of the reaction solution) were investigated, and it was found that the accurately released S2- ions from the thermal decomposition of thioacetamide (TAA) is the central factor for the nucleation and growth of the AgIn5S8 octahedrons. The experimental results indicate that the resultant regular AgIn5S8 octahedrons (AIS-10.6) exhibit the best photocatalytic activity for H2 production among those AgxInyS(x+3y/2) products, and the higher crystallinity and fewer defects of the AgIn5S8 octahedrons compared to the other AgxInyS(x+3y/2) products can retard the photogenerated charge recombination, while those indium atoms with higher density in the exposed {111} facets might be beneficial for the photocatalytic H2 production reaction by acting as active sites to promote the charge separation and transfer processes. The results presented here provide new insights into the significance of crystallinity and exposed facets in the visible-light-responsive activity of AgIn5S8, thus paving new ways into the design and synthesis of high-performance, cost-effective AgIn5S8 photocatalysts for H2 production.