Carboxyl decorated Fe sub(3)O sub(4) nanoparticles for MRI diagnosis and localized hyperthermia

We report the development of carboxyl decorated iron oxide nanoparticles (CIONs) by a facile soft-chemical approach for magnetic resonance imaging (MRI) and hyperthermia applications. These superparamagnetic CIONs ( similar to 10 nm) are resistant to protein adsorption under physiological medium and exhibit good colloidal stability, magnetization and cytocompatibility with cell lines. Analysis of the T sub(2)-weighted MRI scans of CIONs in water yields a transverse relaxivity (r sub(2)) value of 215 mM super(-) super(1) s super(-) super(1). The good colloidal stability and high r sub(2) value make these CIONs as promising candidates for high-efficiency T sub(2) contrast agent in MRI. Further, these biocompatible nanoparticles show excellent self-heating efficacy under external AC magnetic field (AMF). The infrared thermal imaging confirmed the localized heating of CIONs under AMF. Thus, these carboxyl decorated Fe sub(3)O sub(4) nanoparticles can be used as a contrast agent in MRI as well as localized heat activated killing of cancer cells. Furthermore, the active functional groups (COOH) present on the surface of Fe sub(3)O sub(4) nanoparticles can be accessible for routine conjugation of biomolecules/drugs through well-developed bioconjugation chemistry.