Gold nanorods from nanoComposix, San Diego, are surface plasmon resonant rod-shaped nanoparticles with narrow size distributions and uniform shape. The nanorods have absorption peaks that are tunable throughout the visible and short wave near-infrared regions of the electromagnetic spectrum. The company’s purification methods remove ammonium surfactants used during synthesis and replace them with citrate, producing a stable, easily displaceable surface chemistry to use as a base for functionalization with a wide variety of molecules. Also available are polyethylene glycol-functionalized nanorods, as well as carboxyl-terminated surfaces for bioconjugation. Gold nanorods with a high aspect ratio (length/width) have a longer peak resonant wavelength than gold nanorods with a low aspect ratio. The three resonances that are available are 660 nm, 800 nm, and 980 nm, with typical aspect ratios of 2.7, 3.6, and 6.1 respectively. For more information, visit AACC booth 2459 or nanoComposix.