Two-dimensional diffusion-ordered NMR spectroscopy as a tool for monitoring functionalized carbon nanotube purification and composition.
Functionalized carbon nanotube (CNT) derivatives are currently under thorough investigation in different biomedical investigations. In this field of research, the composition of sample either in terms of covalently attached or physisorbed moieties can greatly affect the observed results and hamper the comparison between different studies. Therefore, the availability of a fast and reliable analytical technique to assess both the type of interaction (covalent vs noncovalent) and the composition of CNT conjugates is of great importance. Here we describe that the two-dimensional diffusion-ordered (DOSY) NMR spectroscopy is extremely useful to discriminate between conjugated and unconjugated polyethylene glycol groups in samples obtained by condensation with oxidized single-walled carbon nanotubes (SWNTs). This fast and nondestructive technique allows us to follow the removal of unconjugated polyethylene glycol chains during the purification. In particular, DOSY analysis reveal that about 1/3 (wt %) of the polyethylene glycol used for the condensation remained physisorbed to functionalized SWNTs after dialysis. Complete elimination of physisorbed polyethylene glycol was achieved using diafiltration.
Marega
Riccardo
R
Center of Excellence for Nanostructured Materials (CENMAT), Dipartimento di Scienze Farmaceutiche and INSTM UdR Trieste, Università degli Studi di Trieste, Piazzale Europa 1, 34127 Trieste, Italy.
Aroulmoji
Vincent
V
Bergamin
Massimo
M
Feruglio
Luigi
L
Dinon
Francesca
F
Bianco
Alberto
A
Murano
Erminio
E
Prato
Maurizio
M
D004058:Diffusion; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D012995:Solubility; D013696:Temperature; D014867:Water / Q000737:chemistry
D037742:Nanotubes, Carbon; D014867:Water; D011092:Polyethylene Glycols