AFM imaging of functionalized double-walled carbon nanotubes

Abstract

We present a comparative study of several non-covalent approaches to disperse, debundle and non-covalently functionalize double-walled carbon nanotubes (DWNTs). We investigated the ability of bovine serum albumin (BSA), phospholipids grafted onto amine-terminated polyethylene glycol (PL-PEG(2000)-NH(2)), as well as a combination thereof, to coat purified DWNTs. Topographical imaging with the atomic force microscope (AFM) was used to assess the coating of individual DWNTs and the degree of debundling and dispersion. Topographical images showed that functionalized DWNTs are better separated and less aggregated than pristine DWNTs and that the different coating methods differ in their abilities to successfully debundle and disperse DWNTs. Height profiles indicated an increase in the diameter of DWNTs depending on the functionalization method and revealed adsorption of single molecules onto the nanotubes. Biofunctionalization of the DWNT surface was achieved by coating DWNTs with biotinylated BSA, providing for biospecific binding of streptavidin in a simple incubation step. Finally, biotin-BSA-functionalized DWNTs were immobilized on an avidin layer via the specific avidin-biotin interaction.

An Investigation of 1:1 Adducts of Gallium Trihalides with Triarylphosphines by Solid‐State 69/71Ga and 31P NMR Spectroscopy

“…Additionally, oxidation and etching of the DWNT edges by harsh acidic conditions were applied to generate carboxylic moieties suitable as anchoring points for further modification,9 while mild oxidation conditions have been utilized to shorten the lengths of DWNTs 10. Moreover, several noncovalent approaches have been applied to disperse, debundle, and functionalize DWNTs 11…”

Drug loading, dispersion stability, and therapeutic efficacy in targeted drug delivery with carbon nanotubes

“…[21] and Marega et al [22]. As a fifth candidate, we investigated an amine-terminated phospholipid-PEG (PL-PEG2000-NH 2 ), which is widely used as a dispersion agent for carbon nanotubes [23,24]. In this case the functionalisation was based on non-covalent interactions promoted by the binding of the phospholipid-moiety to the nanotube surface.…”

Evaluation of polyacrylamide-grafted-polyethylene glycol/silica nanocomposite as potential additive in water based drilling mud for reactive shale formation

“…4. AFM analysis is a powerful tool to study the morphological characteristics of any surface (Lamprecht et al, 2009) dispersion of SiO 2 particles in the polymer matrix was observed in the figures. The aggregation and particle growth of silica particles were not observed during the analysis due to the presence of hydrogen bonding, resulting in low macroscopic phase separation and hence, stabilizing silica nanoparticles in the polymer matrix (Li et al, 2004;Jang, and Park, 2002) …”