Gold Nanorods as Multipurpose Building Blocks

Among all of the plasmonic noble metal nanoparticles the gold nanorod (GNR) retains a special place. Its elongated shape gives it unique anisotropic optical and physico-chemical properties. Owing to possibility to control the end-cap geometry, the GNR is the most tunable shape in the terms of localized surface plasmon resonance (LSPR) spectral range. Moreover, the possibility to synthesize GNRs in high yield as colloidal solution makes them cost-effective nanomaterial. The number of prospective applications for colloidal GNRs is still growing – from novel immunolabelling for both optical and electron microscopy, model nanoparticle for emerging field of theranostics, to building blocks of optical metamaterials, literally forming ordered arrays of nano-antennae. In this talk we sum up our results from extensive study of aqueous GNRs colloidal solutions stabilized by cetyltrimethylammonium bromide, synthesized by modified seeded growth approach. We use the strong LSPR dependence on rod aspect ratio to observe GNRs growth kinetics and tune the synthesis to produce high yield monodisperse colloidal solutions. The resulting quality allows us to easily apply the GNRs colloid as a cell-specific light-scattering label in confocal microscopy or to prepare both twoand threedimensional colloidal crystals of GNRs by self-assembly. Using a state-of-the-art scanning electron microscopy we have directly observed such process at drop surface and we have obtained an original video supporting our findings in GNR colloidal crystal formations. We demonstrate visible LSPR coupling effects in optical properties of such ordered arrays.