ABSTRACT
Due to their excellent anti-oxidation performance, CeO2 nanoparticles receive wide attention in pharmacological application. Deep understanding of the anti-oxidation mechanism of CeO2 nanoparticles is extremely important to develop potent CeO2 nanomaterials for anti-oxidation application. Here, we report a detailed study on the anti-oxidation process of CeO2 nanoparticles. The valence state and coordination structure of Ce are characterized before and after the addition of H2O2 to understand the anti-oxidation mechanism of CeO2 nanoparticles. Adsorbed peroxide species are detected during the anti-oxidation process, which are responsible for the red-shifted UV-vis absorption spectra of CeO2 nanoparticles. Furthermore, the coordination number of Ce in the first coordination shell slightly increased after the addition of H2O2. On the basis of these experimental results, the reactivity of coordination sites for peroxide species is considered to play a key role in the anti-oxidation performance of CeO2 nanoparticles. Furthermore, we present a robust method to engineer the anti-oxidation performance of CeO2 nanoparticles through the modification of the defect state and reducibility by doping with Gd(3+). Improved anti-oxidation performance is also observed in cell culture, where the biocompatible CeO2-based nanoparticles can protect INS-1 cells from oxidative stress induced by H2O2, suggesting the potential application of CeO2 nanoparticles in the treatment of diabetes.
Subject(s)
Cerium/chemistry , Nanoparticles/chemistry , Animals , Biocompatible Materials/chemistry , Biocompatible Materials/pharmacology , Cell Line , Coordination Complexes/chemistry , Gadolinium/chemistry , Hydrogen Peroxide/chemistry , Hydrogen Peroxide/toxicity , Oxidation-Reduction , Oxidative Stress/drug effects , Photoelectron Spectroscopy , Rats , Reactive Oxygen Species/chemistry , Spectrum Analysis, Raman , X-Ray Absorption SpectroscopyABSTRACT
To date, our understanding of protein species is still limited. In the present study, 2-DE based proteomics was used to investigate characteristics of protein species in Edwardsiella tarda, a prokaryocyte cell model. In the E. tarda proteome that was analyzed by 2-DE and mass spectrometry, 661 unique proteins representing 1320 protein spots were identified, accounting for 19.0% of gene-coding proteins of the bacterium. 256 out of the 661 identified proteins have different forms of single proteins, forming 915 protein species. Proteins with higher molecular mass, abundance, proportion of Glu, Ile, Lys, Asn, and lower pI and proportion of Leu, Gln, Arg were more likely to be modified and thus showed more protein species. In addition, proteins with more Glu, Ile, Lys, Asn, Gly and Phe were easily modified by phosphorylation. Further investigation indicated that the most protein species were detected in the bacterium in response to environmental stresses, and approximately half of them showed the ability to cope with multiple environmental stresses. These results have revealed general characteristic features of bacterial protein species, and also provided novel insights into biological significance of the protein species.
