Low aggregation magnetic polyethyleneimine complexes with different saturation magnetization for efficient gene transfection in vitro and in vivo

Magnetic polyethyleneimine (PEI) complexes have proven to be simple and efficient carriers for enhanced gene transfection, while the possibility of severe aggregation restricts their further application in vivo. In this study, two negatively charged magnetic nanoparticles (MNPs) with similar sizes but different saturation magnetization values ( Ms,50 and 33 emu g - 1 particles, respectively) were synthesized to assemble with PEI-DNA (PD) complexes via electrostatic interaction. The ternary complexes (MPD) that formed showed low levels of aggregation with narrow size distributions (<150 nm) in aqueous dispersion. Magnetofection of MPD displayed higher transfection activity and lower cytotoxicity compared to that of PD complexes in vitro. Gene expression was significantly enhanced by complexes containing MNPs with higher Ms ( up to 1000-fold in B16F10 cells). The superiority of magnetofection could not be inhibited by serum, and fast accumulation of MPD complexes was observed, especially for MNPs of higher Ms. Meanwhile, improved in vivo transfection efficiency of MPD complexes was obtained under exposure to an external magnetic field.