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Silver nanoparticles (Ag NPs), a commonly used antibacterial nanomaterial, exhibit broad-spectrum antibacterial activity to combat drug-resistant bacteria. However, the Ag NPs often causes a low availability and high toxicity to living bodies due to their easy aggregation and uncontrolled release of Ag+ in the bacterial microenvironment. Here, we report a porous metal−organic framework (MOF)-based Zr-2-amin-1,4-NH2-benzenedicarboxylate@Ag (denoted as UiO-66-NH2-Ag) nanocomposite using an in-situ immobilization strategy where Ag NPs were fixed on the UiO-66-NH2 for improving the dispersion and utilization of Ag NPs. As a result, the reduced use dose of Ag NPs largely improves the biosafety of the UiO-66-NH2-Ag. Meanwhile, after activation by the Ag NPs, the UiO-66-NH2-Ag can act as nanozyme with high peroxidase (POD)-like activity to efficiently catalyze the decomposition of H2O2 to extremely toxic hydroxyl radicals (·OH) in the bacterial microenvironment. Simultaneously, the high POD-like activity synergies with the controllable Ag+ release leads to enhanced reactive oxygen species (ROS) generation, facilitating the death of resistant bacteria. This synergistic antibacterial strategy enables the low concentration (12 μg/mL) of UiO-66-NH2-Ag to achieve highly efficient inactivation of ampicillin-resistant Escherichia coli (AmprE. coli) and endospore-forming Bacillus subtilis (B. subtilis). In vivo results illustrate that the UiO-66-NH2-Ag nanozyme has a safe and accelerated bacteria-infected wound healing. [ABSTRACT FROM AUTHOR]

Lead-based halide perovskite nanoparticles (Pb-PNPs) are promising alternatives for the next-generation of optoelectronic materials, while their nonnegligible biological behavior after exposure are still an enigma. Here, we clarify the translocation, biotransformation, and biodistribution related neurotoxicity of representative CsPbBr 3 PNPs in C57BL/6J mice after intranasal administration through a combination of the feat of advanced synchrotron radiation (SR) and traditional analytical techniques. SR-based microscopic X-ray fluorescence scanning, inductively coupled plasma mass spectrometry and behavioral data demonstrate that CsPbBr 3 PNPs can be transported and accumulated in the hippocampus, easily triggering Ca overload, causing severe damage of hippocampus-dependent learning, memory, and cognition behavior. Meanwhile, SR–based X-ray absorption near-edge spectroscopy analysis also reveals that CsPbBr 3 PNPs can transform into soluble and insoluble lead compounds in different physiological environments. The toxicity of CsPbBr 3 PNPs is higher than that of soluble Pb(Ac) 2 due to the sustained release of Pb ions. The CsPbBr 3 PNPs cause nerve cell apoptosis through triggering intracellular Ca2+ overload, upregulating reactive oxygen species production, while disordering the mitochondrial membrane potential. Our work provides significant insights into the neurological effects and mechanism of Pb-PNPs. [Display omitted] • The neurotoxicity of lead-based perovskite nanoparticles was studied in vivo and in vitro for the first time. • The biodistribution and biotransformation of CsPbBr 3 PNPs were studied by advanced synchrotron radiation techniques. • CsPbBr 3 PNPs can induce Ca overload in brain and damage hippocampal-dependent learning and memory behavior. • CsPbBr 3 PNPs can induce intracellular Ca2+ overload and release reactive oxygen species, leading to neurotoxicity. [ABSTRACT FROM AUTHOR]

Nanomaterials with shifting or mixed redox states is one of the most common studied nanozyme with peroxidase-like activity for chemodynamic therapy (CDT), which can decompose hydrogen peroxide (H 2 O 2) of tumor microenvironment into highly toxic reactive oxygen species (ROS) by a nano-catalytic way. However, most of them exhibit an insufficient catalytic efficiency due to their dependence on catalytic condition. Herein, a potential methodology is proposed to enhance their enzymatic activity by accelerating the redox cycling of these nanomaterials with shifting or mixed redox states in the presence of X-ray. In this study, the nanocomposite consisting of SnS 2 nanoplates and Fe 3 O 4 quantum dots with shifting or mixed redox states (Fe2+/Fe3+) is used to explore the strategy. Under external X-ray irradiation, SnS 2 cofactor as electron donor can be triggered to transfer electrons to Fe 3 O 4 , which promotes the regeneration of Fe2+ sites on the surface of the Fe 3 O 4. Consequently, the regenerated Fe2+ sites react with the overexpressed H 2 O 2 to persistently generate ROS for enhanced tumor therapy. The designed nanocomposite displays the synergistic effects of radiotherapy and CDT. The strategy provides a new avenue for the development of artificial nanozymes with shifting or mixed redox states in precise cancer treatments based on X-ray-enhanced enzymatic efficacy. [ABSTRACT FROM AUTHOR]