Cerium oxide (CeO(2)) nanoparticles display excellent antioxidant properties by scavenging free radicals. However, some studies have indicated that they can cause an adverse response by generating reactive oxygen species (ROS). Hence, it is important to clarify the factors that affect the oxidant/antioxidant activities of CeO(2) nanoparticles. In this work, we report the effects of different buffer anions on the antioxidant activity of CeO(2) nanoparticles. Considering the main anions present in the body, Tris-HCl, sulfate, and phosphate buffer solutions have been used to evaluate the antioxidant activity of CeO(2) nanoparticles by studying their DNA protective effect. The results show that CeO(2) nanoparticles can protect DNA from damage in Tris-HCl and sulfate systems, but not in phosphate buffer solution (PBS) systems. The mechanism of action has been explored: cerium phosphate is formed on the surface of the nanoparticles, which interferes with the redox cycling between Ce(3+) and Ce(4+). As a result, the antioxidant activity of CeO(2) nanoparticles is greatly affected by the external environment, especially the anions. These results may provide guidance for the further practical application of CeO(2) nanoparticles.
Due to the conflicting reports on the antioxidant activity of cerium oxide nanoparticles, much work has been done to explore the factors influencing the antioxidant activity of nano-CeO2.
Excellent cycling and air-storage stability of LiNi0.8Co0.1Mn0.1O2 are obtained through an integrated strategy with a Li2ZrO3 protective layer, Zr4+ doping and the rock-salt interface phase engineering from Li2ZrO3 coating.
Nanoceria has been demonstrated as a potential antioxidative nano-drug. However, its short residence time in the body, toxic solvents involved in the synthesis processes, and especially the poor water solubility hinder its potential clinical applications. In this work, water-soluble chitosan-coated nanoceria particles (CNPs) are synthesized by a facile wet chemical route. The molar weight (MW) and concentration of chitosan do not affect the particles' size and the antioxidative activity of the CNPs over a wide range, and the mechanism is explored further. The behavior of CNPs over time and with a change of pH value were also examined. The CNPs reveal excellent antioxidative activity and stability over seven months at room temperature, and importantly, chitosan widens the pH range for the stable existence of water-soluble nanoceria. As a result, including its inherent advantages of wide availability, non-toxicity, biocompatibility and biodegradability, chitosan can also present the nanoceria with good water-solubility without interfering with its antioxidative activity. In other words, chitosan can enlarge the nanoceria stability over a higher pH range. These factors show the advantages of chitosan as a coating layer, promising the further application of nanoceria in biomedical and biotechnological fields.
Sodium-ion batteries (SIBs) have aroused great interest as large-scale energy storage devices because of the abundant Na resource. However, the lack of high-performance cathode materials is still a big challenge for the practical application of SIBs. Herein, the synergic modification of Zr 4+ d o p i n g a n d Z r O 2 c o a t i n g o n P 2 -s t r u c t u r e Na 0.67 Mn 0.7 Fe 0.2 Co 0.1 O 2 (MFC) has been achieved by a facile Zr(OC 4 H 9 ) 4 -mediated sol−gel method. The rate capability and cycling stability are simultaneously enhanced, and their synergetic mechanism is revealed. The enhancement of the rate capability is largely attributed to the expansion of the interlayer spacing and the enlargement of Na−O bond length, which decreases the Na + migration barrier and the electrostatic attraction between Na and O. This facilitates Na ions intercalation/extraction and enhances the rate capability. The improvement of the cycling stability is first attributed to the protection of ZrO 2 coating, which reduces the side reactions between the electrode and electrolyte and benefits to the stability of the layered structure. In addition, doping of Zr 4+ also reduces the bond length of TM−O/O−O and increases its bonding energy, which further enhances the layered structure stability. Last but not least, the relative content of Mn 3+ is also mitigated which alleviates Jahn−Teller distortion and further enhances the structure stability. In situ X-ray diffraction is also performed to probe the structure evolution of ZrO 2 @MFC during the sodiation/desodiation. The proposed synergetic strategy is also suitable to modify other cathode materials.
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