Surface Chemistry of Gold Nanorods

Gold nanorods have garnered a great deal of scientific interest because of their unique optical properties, and they have the potential to greatly impact many areas of science and technology. Understanding the structure and chemical makeup of their surfaces as well as how to tailor them is of paramount importance in the development of their successful applications. This Feature Article reviews the current understanding of the surface chemistry of as-synthesized gold nanorods, methods of tailoring the surface chemistry of gold nanorods with various inorganic and organic coatings/ligands, and the techniques employed to characterize ligands on the surface of gold nanorods as well as the associated measurement challenges. Specifically, we address the challenges of determining how thick the ligand shell is, how many ligands per nanorod are present on the surface, and where the ligands are located in regiospecific and mixed-ligand systems. We conclude with an outlook on the development of the surface chemistry of gold nanorods leading to the development of a synthetic nanoparticle surface chemistry toolbox analogous to that of synthetic organic chemistry and natural product synthesis.