The gadonanotubes: structural origin of their high-performance MRI contrast agent behavior.

We present an X-ray absorption spectroscopy study of the local structure around the Gd ions loaded within ultra-short carbon nanotubes (US-tubes). For this material, called gadonanotubes (GNTs), detailed modeling and analyses of the X-ray absorption near edge structure (XANES) and extended fine structure (EXAFS) data have helped decipher the structural origin of their exceedingly high-performance MRI contrast agent behavior. Analysis revealed that the Gd ions are surrounded by ∼9 oxygen ions in the first coordination sphere with ∼3 O ions and ∼6 O ions, respectively, centered around 2.

Ruthenium(II) trisbipyridine functionalized gold nanorods. Morphological changes and excited-state interactions.

Gold nanorods synthesized using cetyltrimethylammonium bromide and tetraoctylammonium bromide as stabilizers are functionalized with a thiol derivative of ruthenium(II) trisbipyridyl complex [(Ru(bpy)3(2+)-C5-SH] in dodecanethiol using a place-exchange reaction. The changes in the plasmon absorption bands and transmission electron micrographs indicate significant changes in the gold rod morphology during the place-exchange reaction. The (Ru(bpy)(3)2+-C5-SH in its excited state undergoes quick deactivation when bound to gold nanorods.