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Oxidative Dissolution of Silver Nanoparticles by Biologically Relevant Oxidants: A Kinetic and Mechanistic Study
Author(s) -
Ho ChiMing,
Yau Sammi KingWoon,
Lok ChunNam,
So ManHo,
Che ChiMing
Publication year - 2010
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200900387
Subject(s) - dissolution , chemistry , oxidative phosphorylation , silver nanoparticle , kinetics , reaction rate constant , nanoparticle , nuclear chemistry , inorganic chemistry , nanotechnology , materials science , organic chemistry , biochemistry , physics , quantum mechanics
The oxidative dissolution of silver nanoparticles (AgNPs) plays an important role in the synthesis of well‐defined nanostructured materials , and may be responsible for their activities in biological systems . In this study, we use stopped‐flow spectrophotometry to investigate the kinetics and mechanism of the oxidative dissolution of AgNPs by H 2 O 2 in quasi‐physiological conditions. Our results show that the reaction is first order with respect to both [Ag 0 ] and [H 2 O 2 ], and parallel pathways that involve the oxidation of H 2 O 2 and HO 2 − are proposed. The order of the reaction is independent of the size of the AgNPs (≈5–20 nm). The rate of dissolution increases with increasing pH from 6.0 to 8.5. At 298 K and I =0.1 M , the value of k b is five orders of magnitude higher than that of k a (where k a and k b are the rate constants for the oxidative dissolution of AgNPs by H 2 O 2 and HO 2 − , respectively). In addition , the effects of surface coating and the presence of halide ions on the dissolution rates are investigated. A possible mechanism for the oxidative dissolution of AgNPs by H 2 O 2 is proposed. We further demonstrate that the toxicities of AgNPs in both bacteria and mammalian cells are enhanced in the presence of H 2 O 2 , thereby highlighting the biological relevance of investigating the oxidative dissolution of AgNPs.