In:
Journal of Materials Research, Springer Science and Business Media LLC, Vol. 24, No. 12 ( 2009-12), p. 3559-3568
Abstract:
Amorphous silica shells, used for functionalization of inorganic nanoparticles in bioapplications, were coated on chemically synthesized NaYF 4 :Yb,Er upconversion fluorescent nanoparticles via a reverse microemulsion method by using dual surfactants of polyoxyethylene (5) nonylphenylether and 1-hexanol, and tetraethyl orthosilicate as precursor. NaYF 4 :Yb,Er nanoparticles were equiaxed with a particle size of 11.1 ± 1.3 nm. The thickness of silica shell was ∼8 nm. NaYF 4 :Yb,Er/silica core/shell nanoparticles were well dispersed in solvents such as ethanol and deionized water. The emission intensities of NaYF 4 :Yb,Er/silica core/shell nanoparticles remained the same as that of uncoated nanoparticles after surface functionalization with an amine group using (3-aminopropyl)-trimethoxysilan. Silica, although providing a good barrier to the nonradiative relaxation between the upconversion nanoparticles and the environments, did not enhance the emission intensity of upconversion nanoparticles. To increase the emission intensity of NaYF 4 :Yb,Er/silica core/shell nanoparticles, an undoped NaYF 4 shell (∼3-nm thick) was deposited on the upconversion nanoparticles before the silica coating. The total emission intensity of NaYF 4 :Yb,Er/NaYF 4 /silica core/shell/shell nanoparticles increased by 15 times compared to that without the intermediate NaYF 4 shell. The critical shell thickness of NaYF 4 was ∼3 nm, beyond which no further emission intensity enhancement was observed.
Type of Medium:
Online Resource
ISSN:
0884-2914
,
2044-5326
DOI:
10.1557/jmr.2009.0432
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2009
detail.hit.zdb_id:
54876-5
detail.hit.zdb_id:
2015297-8
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