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BackgroundArsenic is a human carcinogen. Arsenic and its metabolites affect the expression of p53, but whether there are any changes of p53 phosphorylation and ubiquitination levels in human bronchial epithelium cells (BEAS-2B) are not clear after exposure to arsenic and its metabolites. ObjectiveTo study the effects of arsenic and its metabolites monomethylarsic acid (MMA) and dimethylarsinic acid (DMA) on the expression of tumor suppressor gene p53 in BEAS-2B cells. MethodsDifferent concentrations of sodium arsenite (NaAsO2) were used to infect BEAS-2B cells, and the cell viability was detected with CCK-8 reagent to determine the dose and time of NaAsO2 used for the following study. Based on the results of cell viability, the cells were divided into two panels: a sodium arsenide panel and an arsenic methylation metabolite penal. The doses of sodium arsenite were 0, 2, 4, and 6 μmol·L−1 NaAsO2; the arsenic methylation metabolite panel consisted of 0 μmol·L−1 NaAsO2 group (control), 6 μmol· L−1 MMA group, 6 μmol· L−1 DMA group， and 6 μmol· L−1 NaAsO2 group. The cells were collected after 48 h treatment, and the total protein and total RNA were extracted. The relative levels of p53 mRNA expression were determined by quantitative real-time polymerase chain reaction (qRT-PCR), the relative expression levels of p53 protein, p53 Ser9 and Ser15 phosphorylated proteins were determined by Western blot, and the level of p53 ubiquitination was detected by co-immunoprecipitation (CO-IP). ResultsCompared with the control group, the cell viability rates in all BEAS-2B cells treated by NaAsO2 were significantly reduced (P

Gold nanoparticle (AuNP) modification shows great advantages in improving the antioxidant activity of nanoCeO2. However, the improved effect of AuNP modification becomes smaller and even results in the decrease of antioxidant ability due to severe aggregation with increasing nanomaterial concentration. Additionally, the effects of photo-properties of AuNPs on the antioxidant activity of nanoCeO2 have not been studied. In response to these problems, core–shell-shaped Au@CeO2 was synthesized which took Au nanorods (AuNRs) as carriers and had a layer of CeO2 NP coating. The antioxidant activity of Au@CeO2 was evaluated by the UV–vis method in the methyl violet–Fenton system. Results showed that AuNRs could improve the antioxidant activity of nanoCeO2 due to the increase in the amount of Ce3+ on the surface of nanoCeO2, and the enhancing effect remained across the whole experimental concentration range due to the good dispersibility of AuNRs. Additionally, a further increase in the antioxidant ability of Au@CeO2 was found with 5 min visible light irradiation, and continuous irradiation during a 25 min time reaction, which resulted in more obvious enhanced antioxidant ability. This phenomenon was attributed to the localized surface plasmon resonance of AuNRs triggered by photons which induced charge transfer from AuNRs to nanoCeO2, thus making the cyclic transformation between Ce3+ and Ce4+ easier. [ABSTRACT FROM AUTHOR]

Many nanomaterials have been reported to have enzyme-like activities and are considered as nanozymes. As a multifunctional nanozyme, nanoceria has received much attention due to the dual oxidation states of Ce3+/Ce4+ which facilitate redox reactions at the particle surface. Despite the advantages of nanozymes, their limited activity and lack of enzyme specificity are still problems to be resolved. DNA is used to modulate the oxidase activity of nanoceria because it has recently become an important molecule in bionanotechnology. However, the current research on the effect of DNA on the oxidase mimetic activity of nanoceria is contradictory. It has been discovered that nanoceria used in recent works are different, including in particle size, doping and concentration, and these differences may affect the interaction between DNA and nanoceria, and then affect the oxidase mimetic activity of nanoceria. Hence, it is important to clarify the factors that affect the interaction between DNA with nanoceria. In this work, the interactions between DNA and nanoceria with three different morphologies (nanoparticles, nanocubes, and nanorods) have been investigated. Experimental results show that DNA has different influences on the oxidase mimetic activity of nanoceria with different morphologies. The oxidase mimetic activity of CeO2 nanoparticles and nanocubes increased, but that of CeO2 nanorods decreased, after DNA modification. The mechanism of these experimental results has been explored, and it has been found that it is the interaction between cerium and the phosphate backbone of DNA that changes with the different morphologies, resulting in the varying effect of DNA on the oxidase mimetic activity of nanoceria. These results may provide a better understanding of the effect of DNA on the oxidase mimetic activity of nanoceria and promote the applications of nanoceria. [ABSTRACT FROM AUTHOR]