Synthesis of ultra-small gold nanorods: Effect of reducing agent on reaction rate control

Abstract

Recently, anisotropic plasmonic nanoparticles with unique optical properties have seen applications in nanomedicine ranging from optical biosensing to bioimaging and drug delivery. For these uses, uniform gold nanoparticles with a very small size and appropriate aspect ratio that maintain optical properties in near-IR region are desirable. In this study, we synthesized uniform ultra-small gold nanorods with high yield, using hydroquinone as the reducing agent in the growth solution via the seed-mediated method. We were able to control the rate of reduction of gold ions by adjusting the volume of hydroquinone, resulting in the controlled growth rate of gold nanorods. Moreover, by adjusting the volume of the gold precursor, we synthesized ultra-small gold nanorods with dimensions of 16.3 (+/- 2.24) x 5.85 (+/- 0.54) nm (length and diameter). We characterized the ultra-small gold nanorods by UV-visible-NIR spectrophotometry, transmission electron microscopy, x-ray diffraction, and fast Fourier transform techniques.