Iron-filled multiwalled carbon nanotubes surface-functionalized with paramagnetic Gd (III): A candidate dual-functioning MRI contrast agent and magnetic hyperthermia structure

A simple wet chemical method involving only sonication in aqueous GdCl₃ solution was used for surface functionalization of iron-filled multiwalled carbon nanotubes with gadolinium. Functional groups on the sidewalls produced by the sonication provide active nucleation sites for the loading of Gd³⁺ ions. Characterization by EPR, EELS, and HRTEM confirmed the presence of Gd³⁺ ions on the sidewall surface. The room temperature ferromagnetic properties of the encapsulated iron nanowire, saturation magnetization of 40 emu/g and coercivity 600 Oe, were maintained after surface functionalization. Heating functionality in an alternating applied magnetic field was quantified through the measurement of specific absorption rate: 50 W/g_Fe at magnetic field strength 8 kA/m and frequency of 696 kHz. These results point to candidacy for dual-functioning MRI imaging and magnetic hyperthermia structures for cancer therapy.