Facile synthesis of multifunctional nanocomposites with good compatibility for efficient dual-mode T1 and T2 magnetic resonance imaging and gene delivery

Nanostructure-based materials for multimodal imaging have attracted great attentions. Here we report a new formulation integrated gadolinium (Gd) and magnetite (Fe 3 O 4 ) nanoparticles as magnetic resonance (MR) imaging contrast agent at both T 1 mode and T 2 mode. Polyetherimide coated iron oxide (Fe 3 O 4 @PEI) nanoparticles were first synthesized and then conjugated to diethylenetriamine pentaacetic acid (DTPA), which further chelated with Gd 3+ ions (Fe 3 O 4 @PEI@DTPA-Gd). Both phantom and MR studies showed Fe 3 O 4 @PEI@DTPA-Gd nanocomposites could be applied in two modes ( r 1 = 4.7 mM −1  s −1 , r 2 = 131.82 mM −1  s −1 ). MTT and fluorescent staining results also suggested that the nanocomposites had good biocompatibility. Besides, Fe 3 O 4 @PEI@DTPA-Gd nanocomposites exhibited high entrap efficiency when the mass ratio of nanocomposites to DNA was up to 30:1. The in vitro gene transfection ability was also evidenced. Therefore, Fe 3 O 4 @PEI@DTPA-Gd nanocomposites can be employed as a potential candidate for MRI guided clinical diagnosis and gene delivery guided therapy.