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Tailored core-shell-shell nanostructures: sandwiching gold nanoparticles between silica cores and tunable silica shells.
MedLine Citation:
PMID:  17661498     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Size tunable and structure tailored core-shell-shell nanospheres containing silica cores, gold nanoparticle shells, and controlled thicknesses of smooth, corrugated, or porous silica shells over the gold nanoparticles have been synthesized. The synthesis involved the deposition of gold nanoparticles on silica cores, followed by sol-gel processing of tetraethoxysilane (TEOS) or sodium silicate to form dense or porous silica shells, respectively, over the gold nanoparticles. The structures and sizes of the resulting core-shell-shell nanospheres were found to heavily depend on the sizes of the core nanoparticles, the relative population of the gold nanoparticles on each core, and the concentration of TEOS. While a higher TEOS concentration resulted in thicker and more uniform silica shells around individual larger silica cores (approximately > or =250 nm in diameter), the same TEOS concentration resulted in aggregated and twin core-shell-shell nanostructures for smaller silica cores (approximately < or =110 nm in diameter). The thinner silica shells were synthesized by using a lower TEOS concentration. By using sodium silicate (Ung et al. J. Phys. Chem. B 1999, 103, 6770), the porous silica shells were synthesized. Controlled chemical etching of the core-shell-shell nanoparticles with an aqueous KCN solution resulted in corrugated silica shells around the gold nanoparticles or corrugated silica nanospheres with few or no gold nanoparticles. This has allowed synthesis of new types of core-shell-shell nanoparticles with tailored corrugated shells. The nanoporous silica shells provided accessible structures to the embedded metal nanoparticles as observed from the electrochemical response of the gold nanoparticles.
Yan-Li Shi; Tewodros Asefa
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Publication Detail:
Type:  Journal Article     Date:  2007-07-28
Journal Detail:
Title:  Langmuir : the ACS journal of surfaces and colloids     Volume:  23     ISSN:  0743-7463     ISO Abbreviation:  Langmuir     Publication Date:  2007 Aug 
Date Detail:
Created Date:  2007-08-21     Completed Date:  2007-10-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882736     Medline TA:  Langmuir     Country:  United States    
Other Details:
Languages:  eng     Pagination:  9455-62     Citation Subset:  -    
Department of Chemistry, Syracuse University, Syracuse, New York 13244, USA.
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