Linked Life Data

19865761

Source:http://linkedlifedata.com/resource/pubmed/id/19865761

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
43
pubmed:dateCreated
2009-10-29
pubmed:abstractText
Intermediate chemical species involved in the formation dynamics of gold nanoparticles triggered by photoreduction were detected on the temporal range from microseconds to seconds by the near-field heterodyne transient grating method. In the dynamic processes, it was found that not only the ionic species of gold (H[Au(I)Cl(2)], H[Au(III)Cl(4)]), but also the ionic species that formed complex species with the protective agent poly(vinylpyrrolidone) (PVP), (H[Au(I)Cl(2)]-PVP, H[Au(III)Cl(4)]-PVP), were involved. In addition, another chemical species was observed at PVP concentrations greater than 0.4 mM with the HAuCl(4) concentration of 10 mM; its diffusion coefficient was two orders smaller than those for the other ionic species. From the reaction mechanism and the hydrodynamic diameter for the component (3.5 nm) estimated by the Einstein-Stokes equation, we concluded that this component corresponds to gold nanoparticle nuclei. Since the dependence of the nuclei concentration on the PVP concentration showed a similar dependence as those for the H[Au(I)Cl(2)]-PVP and H[Au(III)Cl(4)]-PVP complex species, nucleation of gold nanoparticles occurred by way of the complex species. This reaction mechanism is true for the other four protecting agents (PVP K15, Triton X-100, Tween 20, Brij 58). Furthermore, we investigated the determining factor for the nucleation, and it was clarified that the determining factor for nuclei formation is the molecular ratio between HAuCl(4) and the protective agent, not the concentration of HAuCl(4) itself. Assuming a 2-step mechanism, this result suggests that the reaction is controlled by an initial reduction process aided by the protective agents, after which growth of the nuclei proceeds.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
1463-9084
pubmed:author
pubmed:issnType
Electronic
pubmed:day
21
pubmed:volume
11
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10064-72
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Formation dynamics of gold nanoparticles in poly(vinylpyrrolidone) and other protective agent solutions.
pubmed:affiliation
Department of Applied Chemistry, Chuo University, 1-13-27 Kasuga, Bunkyo, Tokyo 112-8551, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't