Superparamagnetic iron oxide nanoparticles (SPIONs): Development, surface modification and applications in chemotherapy

Superparamagnetic iron oxide nanoparticles with proper surface coatings are increasingly being evaluated for clinical applications such as hyperthermia, drug delivery, magnetic resonance imaging, transfection, and cell/protein separation. To enhance the applicability of magnetic nanoparticles, two main problems must be overcome. First, as the drug coats the particle surface, a significant portion of it is quickly released upon injection (burst effect). Therefore, only small amounts of the drug reach the specific site after, for example, magnetic drug targeting. Second, once the surface-derivatized nanoparticles are inside the cells, the coating is likely digested, leaving the bare particles exposed to other cellular components and organelles, thereby potentially influencing the overall integrity of the cells. To overcome these two shortcomings, iron oxide nanoparticles with cross-linked poly (ethylene glycol)-co-fumarate (PEGF) coating were synthesized. The obtained material was highly stable and easy to handle due to the well-dispersed magnetic nanoparticles. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, even very high concentrations of the novel magnetic nanoparticles were found to be biocompatible. To investigate if the coating could reduce the burst effect, nanoparticles were prepared by incorporating the anticancer drug tamoxifen. The cross-linked PEGF coating reduced the burst effect rate by 21 % in comparison with the noncross-linked tamoxifen nanoparticles. Our results suggest that nanoparticles with coatings based on cross-linked unsaturated aliphatic polyesters are potentially useful to develop novel carriers for drug and gene delivery applications. 1