Synthesis of non-spherical gold nanoparticles

Non-spherical gold nanoparticles such as rods (short, long) (1,2), wires, cubes (3), nanocages (4), (multi-)concentric shells (5), triangular prisms (6-7), as well as other more exotic structures such as hollow tubes, capsules (6), even branched nanocrystals (8-9) have garnered significant research attention in the past few years. They exhibit unique and fine-tuned properties which either strongly differ or are more pronounced from those of symmetric, spherical gold nanoparticles. Their unusual optical and electronic properties, improved mechanical properties and specific surface-enhanced spectroscopies make them ideal structures for emerging applications in photonics, electronics, optical sensing and imaging, biomedical labelling and sensing, catalysis and electronic devices among others (10,11,12,13,14,15,16,17,18). Furthermore, some of these anisotropic nanoparticles enable elucidation of the particle growth mechanism, which in turn makes it possible to predict and systematically manipulate the final nanocrystal morphology (8,1920). Finally, these anisotropic gold nanomaterials provide templates for further generation of novel materials (21,22). This article provides an overview of current research in the area of anisotropic gold nanoparticles. We begin by outlining key properties that they possess; we then describe how to control their morphology. Some of the most innovative synthetic strategies are highlighted together with an emphasis on recent results from our laboratories as well as future perspectives for anisotropic gold nanoparticles as novel materials.