Bi-functional gold-coated magnetite composites with improved biocompatibility.

The effect of gold attachment on the physical characteristics, cellular uptake, gene expression efficiency, and biocompatibility of magnetic iron oxide (MNP) vector was investigated in vitro in BHK21 cells. The surface modification of magnetite with gold was shown to alter the morphology and surface charge of the vector. Nonetheless, despite the differences in the surface charge with and without gold attachment, the surface charge of all vectors were positive when conjugated with PEI/DNA complex, and switched from positive to negative when suspended in cell media containing serum, indicating the adsorption of serum components onto the composite.

Polyethylenimine based magnetic iron-oxide vector: the effect of vector component assembly on cellular entry mechanism, intracellular localization, and cellular viability.

The order of assembly of a magnetic nanoparticle (MNP) vector comprised of the same components (MNP, PEI, and plasmid DNA) on entry mechanism, intracellular localization, and viability of BHK21 cells was investigated. Cellular uptake measurements under four different uptake inhibiting conditions, such as low temperature, depleted cellular ATP, nystatin treatment, and hypertonic environment, show that the cellular entry mechanism of the MNP vector was mediated via clathrin endocytosis. Despite different vector component assembly, all MNP vectors were taken up by the cells through the same mechanism.

Assembly of polyethylenimine-based magnetic iron oxide vectors: insights into gene delivery.

The use of a nonviral magnetic vector, comprised of magnetic iron oxide nanoparticles (MNP), polyethylenimine (PEI), and plasmid DNA, for transfection of BHK21 cells under a magnetic field is presented. Four different vector configurations were studied by systematically varying the mixing order of MNP, PEI, and DNA. The assembly of the vector has significant effects on its vector size, surface charge, cellular uptake, and level of gene expression.