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 (Fe3O4) nanoparticles as magnetic resonance (MR) imaging contrast agent at both T1 mode and T2 mode. Polyetherimide coated iron oxide (Fe3O4@PEI) nanoparticles were first synthesized and then conjugated to diethylenetriamine pentaacetic acid (DTPA), which further chelated with Gd3+ ions (Fe3O4@PEI@DTPA-Gd). Both phantom and MR studies showed Fe3O4@PEI@DTPA-Gd nanocomposites could be applied in two modes (r1 = 4.7 mM−1 s−1, r2 = 131.82 mM−1 s−1). MTT and fluorescent staining results also suggested that the nanocomposites had good biocompatibility. Besides, Fe3O4@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, Fe3O4@PEI@DTPA-Gd nanocomposites can be employed as a potential candidate for MRI guided clinical diagnosis and gene delivery guided therapy.