Mechanisms of the pH dependent generation of hydroxyl radicals and oxygen induced by Ag nanoparticles. 2012

Weiwei He, and Yu-Ting Zhou, and Wayne G Wamer, and Mary D Boudreau, and Jun-Jie Yin
Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD 20740, USA.

Many of the chemical and biological effects of silver nanoparticles (Ag NPs) are attributed to the generation of reactive oxygen species (ROS). ESR spectroscopy was used to provide direct evidence for generating ROS during decomposition of H(2)O(2) assisted by Ag NPs. Hydroxyl radical formation was observed under acidic conditions and was accompanied by dissolution of Ag NPs. In contrast, evolution of O(2) was observed in alkaline solutions containing H(2)O(2) and Ag NPs; however, no net dissolution of Ag NPs was observed due to re-reduction of Ag(+) as evidenced by a cyclic reaction. Since H(2)O(2) is a biologically relevant product being continuously generated in cells, these results obtained under conditions mimicking different biological microenvironments may provide insights for finding new biomedical applications for Ag NPs and for risk assessment.

UI MeSH Term Description Entries
D007501 Iron A metallic element with atomic symbol Fe, atomic number 26, and atomic weight 55.85. It is an essential constituent of HEMOGLOBINS; CYTOCHROMES; and IRON-BINDING PROTEINS. It plays a role in cellular redox reactions and in the transport of OXYGEN. Iron-56,Iron 56
D010084 Oxidation-Reduction A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471). Redox,Oxidation Reduction
D010100 Oxygen An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration. Dioxygen,Oxygen-16,Oxygen 16
D004578 Electron Spin Resonance Spectroscopy A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING. ENDOR,Electron Nuclear Double Resonance,Electron Paramagnetic Resonance,Paramagnetic Resonance,Electron Spin Resonance,Paramagnetic Resonance, Electron,Resonance, Electron Paramagnetic,Resonance, Electron Spin,Resonance, Paramagnetic
D006861 Hydrogen Peroxide A strong oxidizing agent used in aqueous solution as a ripening agent, bleach, and topical anti-infective. It is relatively unstable and solutions deteriorate over time unless stabilized by the addition of acetanilide or similar organic materials. Hydrogen Peroxide (H2O2),Hydroperoxide,Oxydol,Perhydrol,Superoxol,Peroxide, Hydrogen
D006863 Hydrogen-Ion Concentration The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D012834 Silver An element with the atomic symbol Ag, atomic number 47, and atomic weight 107.87. It is a soft metal that is used medically in surgical instruments, dental prostheses, and alloys. Long-continued use of silver salts can lead to a form of poisoning known as ARGYRIA.
D013056 Spectrophotometry, Ultraviolet Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Ultraviolet Spectrophotometry
D017665 Hydroxyl Radical The univalent radical OH. Hydroxyl radical is a potent oxidizing agent.
D053768 Metal Nanoparticles Nanoparticles produced from metals whose uses include biosensors, optics, and catalysts. In biomedical applications the particles frequently involve the noble metals, especially gold and silver. Metal Nanocrystals,Metallic Nanocrystals,Metallic Nanoparticles,Metal Nanocrystal,Metal Nanoparticle,Metallic Nanocrystal,Metallic Nanoparticle,Nanocrystal, Metal,Nanocrystal, Metallic,Nanocrystals, Metal,Nanocrystals, Metallic,Nanoparticle, Metal,Nanoparticle, Metallic,Nanoparticles, Metal,Nanoparticles, Metallic

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