Synthesis and characterization of gold nanorods

Abstract

Gold has unique properties in the macro scale, namely, low electrical resistance, protection against oxidation among many other characteristics. However, when going to nanoscale, particles made of gold, and many other noble materials, also present striking properties which opens a wide range of applications [1]. Gold nanorods (GN) with well-defined sizes can be used as sensors due to its high biocompatibility and unique plasmon resonant properties. In recent applications, GN has been used to enhance chiral recognition of enantiomers, drug carriers for photothermotherapy and promote optical information storage. The efficiency of these applications depends on the fine-tuning of the rods radius and aspect ratios [2]. Therefore, optimized synthesis control and detailed structural characterization of the GN on different synthesis times are crucial for the selection and application of the synthetized nanorods. In this work a small change in the traditional synthesis procedure [3] led to a synthesis of GN with slower reaction speed and nanorods with larger radius and smaller aspect ratios when compared to the original synthesis [4]. The structural characterization of the GN was performed using Small-Angle X-Ray scattering, X-Ray Diffraction, Dynamic light scattering, Transmission Electron microscopy and Ultraviolet-visible spectroscopy. As a result, the time evolution of the rods dimensions could be followed and described (figure 1). As will be shown, the structural characterization enabled the description of the parameters as a function of synthesis time as well as reliable quantification of molar concentrations.