Two-dimensional diffusion-ordered NMR spectroscopy as a tool for monitoring functionalized carbon nanotube purification and composition

Riccardo Marega, Vincent Aroulmoji, Massimo Bergamin, Luigi Feruglio, Francesca Dinon, Alberto Bianco, Erminio Murano, Maurizio Prato

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)2051-2058
Number of pages8
JournalACS nano
Volume4
Issue number4
DOIs
Publication statusPublished - 27 Apr 2010
Externally publishedYes

Keywords

  • Carbon nanotube
  • Covalent functionalization
  • DOSY
  • NMR
  • Purification

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