Article

Synthesis, Characterization, and Tunable Optical Properties of Hollow Gold Nanospheres†, J. Phys. Chem. B. 110, 19935-19944

Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA.
The Journal of Physical Chemistry B (Impact Factor: 3.3). 11/2006; 110(40):19935-44. DOI: 10.1021/jp062136a
Source: PubMed

ABSTRACT

Nearly monodisperse hollow gold nanospheres (HGNs) with tunable interior and exterior diameters have been synthesized by sacrificial galvanic replacement of cobalt nanoparticles. It is possible to tune the peak of the surface plasmon band absorption between 550 and 820 nm by carefully controlling particle size and wall thickness. Cobalt particle size is tunable by simultaneously changing the concentration of sodium borohydride and sodium citrate, the reducing and capping agent, respectively. The thickness of the gold shell can be varied by carefully controlling the addition of gold salt. With successful demonstration of ensemble as well as single HGN surface-enhanced Raman scattering, these HGNs have shown great potential for chemical and biological sensing applications, especially those requiring nanostructures with near-IR absorption.

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Available from: Tammy Y. Olson, May 29, 2014
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    • "and Au-A-2 (Figure 6d) at around 550 nm, which is due to the presence of larger octahedral Au NPs in the former two nanocomposites. SPR peak was reported to shift towards longer wavelength with the increasing size of Au NPs,[15, 18, 46, 47] and so the SPR peak shift agreed well with the observations from TEM. Moreover, Noguez reported that compared to polyhedral nanoparticles, spherical ones will have blue-shifted SPR peaks.[48] "
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    • "These values are in a reasonable agreement with the experimentally determined surface stress of small gold nuclei (1.14 J/m 2 at 50 C)[45]. Though no direct comparison of surface stress and surface energy is possible, it should be noted that the values of surface stress obtained in the present work are in a good agreement with the value of 1.36 J/m 2 for the surface energy of Au[2,33]. We would like to emphasize that while the compressive nature of the capillary-induced stress is obvious for the solid nanoparticles[45], this is not the case for the PGNs exhibiting both convex and concave regions of internal porosity. "
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    • "For example, hollow gold nanoparticles are much more efficient than their solid counterparts at heat generation when exposed to near-infrared radiation , which makes them attractive for cancer theranostic applications [5]. The most widespread methods for the synthesis of hollow nanostructures are based on the Kirkendall effect [6] and on galvanic replacement reactions [2] [7] [8]. The latter method allows reproducible synthesis of hollow nanoparticles, but they often exhibit polycrystalline microstructure and high density of defects [8]. "
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