Nanoceria dissolution at acidic pH by breaking off the catalytic loop

Scavenging Reactive Oxygen Species by Cerium Oxide Nanoparticles Prevents Death in a Peripheral T Cell Lymphoma Preclinical Mouse Model

Cancer cell survival and proliferation are correlated with increased metabolic activity and consequent oxidative stress, driving metabolic shifts that interfere with the immune response to malignant cells. This is the case of high-energy-demanding angioimmunoblastic T cell lymphoma (AITL), a highly aggressive cancer with poor survival rates, where malignant CD4+ PD-1high T cells show increased mitochondrial activity and Reactive oxygen species (ROS) accumulation. Here, we report that administration of ROS scavenging cerium oxide (CeO2) nanoparticles in an AITL preclinical mouse model leads to their preferential accumulation in the spleen, where the CD4+ PD-1high T cells driving malignancy were significantly reduced. This was accompanied by activation of previously exhausted cytotoxic CD8+ T cells, restoring their potent antitumor function. As a result, survival rates dramatically increase with no observed toxicity to healthy cells or tissues. Overall, it highlights the correlation between increased energy demand, increased mitochondrial mass, increased PD-1 expression, increased ROS production, and immune suppression and how this vicious loop can be stopped by scavenging ROS.

Enhancing antioxidant properties of CeO2 nanoparticles with Nd3+ doping: structural, biological, and machine learning insights

The antioxidant capabilities of nanoparticles are contingent upon various factors, including their shape, size, and chemical composition. Herein, novel Nd-doped CeO2 nanoparticles were synthesized and the neodymium content was varied to investigate the synergistic impact on the antioxidant properties of CeO2 nanoparticles. Incorporating Nd3+ induced changes in lattice parameters and significantly altered the morphology from nanoparticles to nanorods. The biological activity of Nd-doped CeO2 was examined against pathogenic bacterial strains, breast cancer cell lines, and antioxidant models. The antibacterial and anticancer activities of nanoparticles were not observed, which could be associated with the Ce3+/Ce4+ ratio. Notably, the incorporation of neodymium improved the antioxidant capacity of CeO2. Machine learning techniques were employed to forecast the antioxidant activity to enhance understanding and predictive capabilities. Among these models, the random forest model exhibited the highest accuracy at 96.35%, establishing it as a robust computational tool for elucidating the biological behavior of Nd-doped CeO2 nanoparticles. This study presents the first exploration of the influence of Nd3+ on the structural, optical, and biological attributes of CeO2, contributing valuable insights and extending the application of machine learning in predicting the therapeutic efficacy of inorganic nanomaterials.

Exploring the Long-Term Tissue Accumulation and Excretion of 3 nm Cerium Oxide Nanoparticles after Single Dose Administration

Nanoparticle (NP) pharmacokinetics significantly differ from traditional small molecule principles. From this emerges the need to create new tools and concepts to harness their full potential and avoid unnecessary risks. Nanoparticle pharmacokinetics strongly depend on size, shape, surface functionalisation, and aggregation state, influencing their biodistribution, accumulation, transformations, and excretion profile, and hence their efficacy and safety. Today, while NP biodistribution and nanoceria biodistribution have been studied often at short times, their long-term accumulation and excretion have rarely been studied. In this work, 3 nm nanoceria at 5.7 mg/kg of body weight was intravenously administrated in a single dose to healthy mice. Biodistribution was measured in the liver, spleen, kidney, lung, brain, lymph nodes, ovary, bone marrow, urine, and faeces at different time points (1, 9, 30, and 100 days). Biodistribution and urinary and faecal excretion were also studied in rats placed in metabolic cages at shorter times. The similarity of results of different NPs in different models is shown as the heterogeneous nanoceria distribution in organs. After the expectable accumulation in the liver and spleen, the concentration of cerium decays exponentially, accounting for about a 50% excretion of cerium from the body in 100 days. Cerium ions, coming from NP dissolution, are most likely excreted via the urinary tract, and ceria nanoparticles accumulated in the liver are most likely excreted via the hepatobiliary route. In addition, nanoceria looks safe and does not damage the target organs. No weight loss or apathy was observed during the course of the experiments.

Efficient and recyclable degradation of organic dye pollutants by CeO2@ZIF-8 nanozyme-based non-photocatalytic system

Advanced oxidation processes-based catalysis system as the most typical pollutant degradation technology always suffer from poor durability and photo-dependent. Inspired by the fact that some nanomaterials exhibit catalytic properties closer to natural enzymes, a high peroxidase-like activity and stability CeO₂@ZIF-8 nanozyme was synthesized in this study for non-photodegradation of dyes pollution. Multiple characterization techniques were applied to prove the successful synthesis of the nanozyme. The influence of different parameters on the catalytic degradation of organic dye by nanozyme was investigated. This nanozyme achieved a maximum degradation efficiency of 99.81% for methyl orange and maintained its catalytic performance in repeated experiments. Possible degradation intermediates and pathways for methyl orange were then proposed. In addition, the CeO₂@ZIF-8 loaded starch/agarose films were prepared for the portable and recyclable remediation of real dye wastewater, which maintained more than 80% degradation efficiency after 5 successive cycles. These results suggested that nanozyme based non-photocatalytic system is a potential catalyst for dye degradation and it opens a new avenue to develop high-performance and recyclable catalysts for pollutant remediation.