Wet Chemistry Approaches for Synthesis of Gold Nanospheres, Nanorods and Nanostars
Jyoti Verma, Henk A. Van Veen, Sumit Lal and Cornelis J.F. Van Noorden
Affiliation: Department of Medicine, Harvard Medical School, 221 Longwood Ave, MA 02115, USA.
Keywords: Gold nanoparticles, gold nanorods, gold nanostars, seed-mediated growth, wet chemistry.
This paper describes the synthesis of gold nanorods, gold nanospheres and gold nanostars using modified versions
of existing seed-mediated growth methods. The nanoparticles have been characterized on the basis of their morphology
and optical properties using transmission electron microscopy (TEM) and spectrophotometry. Gold nanorods were
synthesized using ascorbic acid as reducing agent, gold nanospheres were synthesized using mercaptosuccinic acid as stabilizing/
reducing agent and gold nanostars were synthesized using ascorbic acid as reducing agent and silver ion as anisotropic
growth agent. Gold nanorods showed a sharp absorbance spectrum with peaks at 447 nm and 715 nm. Gold nanospheres
were spherical, non porous with a diameter of 14-59 nm. The nanospheres were polycrystalline and showed variable
branch length that was dependent on the relative proportions of ascorbic acid and gold salts. The spectra of gold
nanostars revealed a broad absorbance pattern in the range of 660-775 nm and 930-1000 nm that may be attributed to
plasmon resonance of nanostar core and plasmon resonance of nanostar branches, respectively.
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