Dowding Janet M, Seal Sudipta, Self William T
Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA.
Drug Deliv Transl Res. 2013 Aug 1;3(4):375-9. doi: 10.1007/s13346-013-0136-0.
Cerium oxide nanoparticles (CeO2 NPs) have been shown to possess a substantial oxygen storage capacity via the interchangeable surface reduction and oxidation of cerium atoms, cycling between the Ce(4+) and Ce(3+) redox states. It has been well established in many studies that depending on their reactivity and surface chemistry, CeO2 NPs can effectively convert both reactive oxygen species (superoxide, O2 (•-), and hydrogen peroxide) into more inert species and scavenge reactive nitrogen species (RNS)(nitric oxide, •NO), both in vitro and in vivo. Since much of damage attributed to •NO and O2 (•-) is actually the result of oxidation or nitration by peroxynitrite or its breakdown products and due to the multiple species that these nanoparticles target in vivo, it was logical to test their interaction with the highly reactive molecule peroxynitrite (ONOO(-)). Here, we report that CeO2 NPs significantly accelerated the decay of ONOO(-) by three independent methods. Additionally, our data suggest the ability of CeO2 NPs to interact with ONOO(-) is independent of the Ce(3+)/Ce(4+) ratio on the surface of the CeO2 NPs. The accelerated decay was not observed when reactions were carried out in an inert gas (argon), suggesting strongly that the decay of peroxynitrite is being accelerated due to a reaction of CeNPs with the carbonate radical anion. These results suggest that one of the protective effects of CeO2 NPs during RNS is likely due to reduction in peroxynitrite or its reactive breakdown products.
氧化铈纳米颗粒（CeO2 NPs）已被证明通过铈原子的可互换表面还原和氧化，在Ce(4+)和Ce(3+)氧化还原态之间循环，具有相当大的储氧能力。许多研究已经充分证实，根据其反应性和表面化学性质，CeO2 NPs在体外和体内都能有效地将活性氧（超氧化物、O2(•-)和过氧化氢）转化为更惰性的物质，并清除活性氮物质（RNS）（一氧化氮，•NO）。由于许多归因于•NO和O2(•-)的损伤实际上是过氧亚硝酸盐或其分解产物氧化或硝化的结果，并且由于这些纳米颗粒在体内靶向多种物质，因此测试它们与高活性分子过氧亚硝酸盐（ONOO(-)）的相互作用是合乎逻辑的。在此，我们报告CeO2 NPs通过三种独立方法显著加速了ONOO(-)的衰变。此外，我们的数据表明CeO2 NPs与ONOO(-)相互作用的能力与CeO2 NPs表面的Ce(3+)/Ce(4+)比率无关。当反应在惰性气体（氩气）中进行时，未观察到加速衰变，这强烈表明过氧亚硝酸盐的衰变是由于CeNPs与碳酸根自由基阴离子的反应而加速的。这些结果表明，CeO2 NPs在RNS期间的保护作用之一可能是由于过氧亚硝酸盐或其活性分解产物的减少。
