Cu2+-Complex of hydrophilic nitrogen-rich polymer dots applied as a new MRI contrast agent

We report on a novel Cu2+-complex of nitrogen-rich polymer dots for magnetic resonance imaging (MRI). The N-rich polymer dots are prepared from N-vinyl imidazole (VIm) by a one-pot hydrothermal synthesis at 220 degrees C (24 h) and used later on to fabricate a Cu2+-PVIm dot complex via efficient incorporation of Cu2+ into aqueous medium. The obtained Cu2+-PVIm dot complexes display relaxivity (r(1) = 1.05 mM(-1) s(-1)) two times higher than Cu2+ in aqueous solution (r(1) = 0.43 mM-1 s(-1)) and three times higher than Cu2+ in aqueous solution coordinated with VIm monomers (r(1) = 0.32 mM(-1) s(-1)), which show a remarkable contrast enhancement for T-1-weighted MRI while efficiently labeling MCF-7 cells and other biomedical applications.