Improving the valence self-reversible conversion of cerium nanoparticles on titanium implants by lanthanum doping to enhance ROS elimination and osteogenesis

Equipped with anti-oxidative properties, cerium oxide nanoparticles (CNPs) are gradually being adopted over the years in the field of oxidative stress research. However, the effects of CNPs may be diminished when under the influence of prolonged and substantially elevated levels of oxidative stress. Therefore, it is imperative to enhance the efficacy of CNPs to resist oxidative stress. In this study, our approach involves the fabrication of titanium surface CNPs coatings doped with different concentrations of lanthanum ions (La³⁺) and the investigation of their local anti-oxidative stress potential. The physicochemical characterization showed that the La-CNPs groups had a substantial increase in the generation of oxygen vacancies within the CNPs structure with the increase of La doping concentration. In vitro findings proofed that the cytocompatibility of different La-CNPs coatings showed a trend of increasing first and then decreasing with the increase of La doping concentration under oxidative stress microenvironment. Among these groups, the 30 % La-CNPs group presented the best cell proliferation and osteogenic differentiation which could activate the FoxO1 pathway, then upregulated the expression of SOD1 and CAT, and finally resulted in the inhibition of ROS production. In vivo results further confirmed that the 30 % La-CNPs group showed significant osteogenic effects in two rat models (osteoporosis and diabetes models). In conclusion, we believe that the 30 % La-CNPs coating holds promising potential for its implant applications in patients with oxidative stress-related diseases.

Biomineralization-Inspired Synthesis of Cerium-Doped Carbonaceous Nanoparticles for Highly Hydroxyl Radical Scavenging Activity

Cerium oxide nanoparticles recently have received extensive attention in biomedical applications due to their excellent anti-oxidation performance. In this study, a simple, mild, and green approach was developed to synthesize cerium-doped carbonaceous nanoparticles (Ce-doped CNPs) using bio-mineralization of bull serum albumin (BSA) as precursor. The resultant Ce-doped CNPs exhibited uniform and ultrasmall morphology with an average size of 14.7 nm. XPS and FTIR results revealed the presence of hydrophilic group on the surface of Ce-doped CNPs, which resulted in excellent dispersity in water. The CCK-8 assay demonstrated that Ce-doped CNPs possessed favorable biocompatibility and negligible cytotoxicity. Using H₂O₂-induced reactive oxygen species (ROS) as model, Ce-doped CNPs showed highly hydroxyl radical scavenging capability. Furthermore, flow cytometry and live-dead staining results indicated that Ce-doped CNPs protected cells from H₂O₂-induced damage in a dose-dependent effect, which provided a direct evidence for anti-oxidative performance. These findings suggest that Ce-doped CNPs as novel ROS scavengers may provide a potential therapeutic prospect in treating diseases associated with oxidative stress.

Bioavailability of CeO2 and SnO2 nanoparticles evaluated by dietary uptake in the earthworm Eisenia fetida and sequential extraction of soil and feed

The growing number of nanotechnology products on the market will inevitably lead to the release of engineered nanomaterials with potential risk to humans and environment. This study set out to investigate the exposure of soil biota to engineered nanoparticles (NPs). Cerium dioxide (CeO2 NPs) and tin dioxide nanoparticles (SnO2 NPs) were radiolabelled using neutron activation, and employed to assess the uptake and excretion kinetics in the earthworm Eisenia fetida. Through sequential extraction, NPs bioavailability in two contrasting soils and in earthworm feed was also investigated. Neither CeO2 NPs nor SnO2 NPs bioaccumulated in earthworms, and both were rapidly excreted when worms were transferred to clean soil. Low bioavailability was also indicated by low amounts of NPs recovered during extraction with non-stringent extractants. CeO2 NPs showed increasing mobility in organic soil over time (28 days), indicating that organic matter has a strong influence on the fate of CeO2 NPs in soil.

Toxicity of CeO2 nanoparticles at different trophic levels--effects on diatoms, chironomids and amphibians

The aim of the present work is to provide wider information on the toxicity of cerium dioxide nanoparticles (CeO2 NPs) in aquatic environments, by studying the toxicity of two types of CeO2 NPs for four species (diatoms Nitzschia palea, the sediment-dwelling invertebrate Chironomus riparius, and the amphibian larvae Xenopus laevis and Pleurodeles waltl.). The two types of CeO2 NPs have different intrinsic properties: some of them are small citrate-coated spheres (2-5 nm), and the others are larger uncoated plates (20-60 nm). Acute toxicity (mortality at 48 or 96 h, depending on the test-organism) was assessed for the four species, from 0.1 to 100 mg L(-1) of NPs. Sub-lethal effects were assessed on chironomids exposed between 0.01 and 1 mg L(-1) of NPs. Mortality, growth inhibition and genotoxic effects were evaluated on amphibian larvae from 0.1 to 10 mg L(-1). Results reveal that no acute toxicity occurs on any species after short exposures, even at the highest concentrations. Mortality (35%) is observed on Xenopus larvae after 12d of exposure at the highest concentration of one type of NPs. No significant effects were observed on chironomids during chronic exposure. Xenopus larvae growth was inhibited from 1 mg L(-1) of both NPs while growth inhibition is observed on Pleurodeles only at the highest concentration of one type of NPs. No genotoxicity was observed on Xenopus but Pleurodeles exhibited dose-dependent genotoxic effects when exposed to one type of NPs. Observed differences in toxicity are discussed focusing on the studied compartment, routes of exposure, species and NPs.