Well-ordered end-to-end linkage of gold nanorods.

In this study, it is found that as-prepared gold nanorods can be linked to each other in an end-to-end way by using cysteine as a molecular bridge. Both transmission electron microscopy and UV-visible optical spectroscopy demonstrated the uniaxial assembly of the gold nanorods. The controlled addition of cysteine into the gold nanorod solution resulted in their preferential binding to the two ends of the gold nanorods. As a result, end-to-end assembly was achieved through cooperative hydrogen bonding of bound cysteine molecules. The as-synthesized end-to-end linked assembly of gold nanorods is well ordered and on a large scale. For comparison, three other neutral amino acids, glycine, alanine and valine, were also investigated but the orderliness of their assembly is not as good as that in the case of cysteine.