Gold dendrimer encapsulated nanoparticles as labeling agents for multiwalled carbon nanotubes

In this paper, we report the functionalization of the surface of multiwalled carbon nanotubes (MWNTs) with Au dendrimer encapsulated nanoparticles (DENs). The results show that, when pristine MWNTs having hydrophobic surfaces are exposed to DENs, the dendrimers aggregate on the MWNT surface. However, when the MWNTs are oxidized in acid prior to exposure to DENs, well-dispersed submonolayer coverages of Au nanoparticles are observed on the MWNT surface. This suggests that acid-induced debundling of the nanotubes is an essential prerequisite for attachment of nearly monodisperse DENs. Electron microscopy and NMR spectroscopy confirm that the structures of the DENs and dendrimers are retained after immobilization on the surface of acid-functionalized MWNTs.