Chemical modification of multiwalled carbon nanotube with a bifunctional caged ligand for radioactive labelling

Carboxyl-functionalized multiwalled carbon nanotubes (MWCNTs) have been successfully radiolabelled with cobalt-57 (Co-57) (T-1/2 = 270 days) via the attachment of the bifunctional caged ligand MeAMN(3)S(3)sar. In this study MeAMN(3)S(3)sar has been synthesized and coupled to MWCNTs to form the conjugate MWCNT MeAMN(3)S(3)sar. Synthesis was confirmed with nuclear magnetic resonance. X-ray photoelectron spectroscopy (XPS) confirmed the conjugation. Non-radioactive labelling of this conjugate was completed with Cu(II) ions to confirm the stability of the MeAMN(3)S(3)sar after coupling with the MWCNTs. The complexation of the Cu(II) was also confirmed with XPS. Transmission electron microscopy was used to demonstrate that the coupling reaction had a negligible effect on the size and shape of the MWCNTs. Radiolabelling of the MWCNT MeAMN(3)S(3)sar conjugate and pristine (untreated) MWCNTs (nonspecific) with the gamma-emitting radioactive isotope Co-57 were compared. The radiolabelling efficiency of the MWCNT MeAMN(3)S(3-)sar conjugate was significantly higher (95% vs. 0.1%) (P <= 0.001) than for the unconjugated pristine MWCNTs. This will allow for the potential tracking of nanoparticle movement in vitro and in vivo. Crown Copyright (C) 2013 Published by Elsevier Ltd. on behalf of Acta Materialia Inc. All rights reserved.