You Sang

We report a novel, simple, highly selective and versatile approach for the end-to-end assembly of gold nanorods (GNRs) by means of the specific molecular recognition between thymine-rich (T-rich) oligonucleotides and mercury(II).

It is known that universality and controllability over nanocrystal orientation must be accomplished to facilitate the potential applications of metal nanocrystals in the areas of photonics, electronics, and optics. The facile fabrication of linear chains of Au nanorods and bifurcated junctions of nanorods/nanospheres is achieved via the crosslinking of H-type tetrakis(4-sulfonatophenyl)porphyrin aggregates in solution. The tuning of the plasmon coupling between the Au nanocrystals is demonstrated by varying the porphyrin concentration and thus the interparticle gap distances. Finite-difference time-domain calculations show that the red shift of the plasmon band exhibits a nearly exponential decay with increasing interparticle gap distances, thus giving rise to a "plasmon ruler equation." The gap distances determined according to this equation agree well with the experimental observations and further confirm the porphyrin-directed assembly process. The interaction mechanism between the Au nanorods and porphyrins is further investigated by a biological procedure using the dark-field light scattering technique.

We report a novel strategy to fabricate metal nanoparticle/carbon nanotube hybrids with unique plasmon properties as well as biocompatibility and further apply them as efficient dark field light scattering agents for cancer cell imaging.