pH-tuned synthesis of gold nanostructures from gold nanorods with different aspect ratios

Fine control of gold nanoparticle shape can be achieved by varying the pH of the reaction medium in the presence of gold nanorods, which acted as seeds. Under various pH (3.6-9.6) values of the reaction medium, different shapes of gold nanostructural architectures, from rectangle-, 'dogbone'- and peanut-like outlines to branched multipods with corrugated surface, can be fabricated in high yield from gold nanorods with aspect ratio 2.9 and 2.1. These shape changes of gold nanorods directly influence their optical properties.