Introduction:
Recently, some studies have focused on dendrimer nanopolymers as an MRI contrast agent or a vehicle for gene and drug delivery. Considering the suitable properties of these materials, they are appropriate candidates for coating iron oxide nanoparticles which are applied to magnetic hyperthermia. To the best of our knowledge, the novelty of this study is the investigation of fourth-generation dendrimer-coated iron oxide nanoparticles (G4@IONPs) in magnetic hyperthermia and MR imaging.
Materials and Methods: IONPs were synthesized via co-precipitation and coated with the fourth generation (G4) of poly amidoamine (PAMAM) dendrimer. The cytotoxicity of G4@IONPs with different concentrations was assessed in hum a breast cancer cell line (MCF7) and human fibroblast cell line (HDF1). Hemolysis and stability of G4@IONPs were investigated and also, the interaction of these particles with MCF7 cells was assessed by Prussian blue staining. Heat generation and specific absorption rate (SAR) were calculated from measurement and simulation results at 200 and 300 kHz. MCF7 and HDF1 cells were incubated with G4@IONPs for 2 h and then put into the magnetic coil for 120 min. relaxometry experiments were performed with different concentrations of G4@IONPs with T1 and T2-weighted MR images.
 
Results: The TEM results showed that G4@IONPs were 10±4 nm. The in vitro toxicity assessments showed that synthesized NPs had low toxicity. The viability of MCF7 cells incubated with G4@IONPs decreased significantly after magnetic. Also, MR imaging revealed that G4@IONPs improved transverse relaxivity (r2) significantly.
 
Conclusion: Our results encouraged the future application of G4@IONPs in magnetic hyperthermia and MR imaging.