Citrate capped superparamagnetic iron oxide nanoparticles used for hyperthermia therapy

Abstract

Superparamagnetic magnetite nanoparticles (MNP) of about 10 nm were designed with proper physico-chemical characteristics by an economic, biocompatible chemical coprecipitation of Fe2+ and Fe3+ in an ammonia solution, for hyperthermia applications. Synthetic methodology has been developed to get a well dispersed and homogeneous aqueous suspension of MNPs. Citric acid was used to stabilize the magnetite particle suspension, it was anchored on the surface of freshly prepared MNPs by direct addition method. Carboxylic acid terminal group not only render the particles more water dispersible but also provides a site for further surface modification. The naked MNPs are often insufficient for their stability, hydrophilicity and further functionalization. To overcome these limitations, citric acid was conjugated on the surface of the MNPs. The microstructure and morphology of the nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and the interaction between citric acid and MNPs were characterized by Fourier transform infrared spectroscopy (FTIR), whereas the magnetic properties were investigated by vibrating sample magnetometry (VSM). Magnetic measurement revealed that the saturation magnetization of the nanoparticles was 74 emu/g and the nanoparticles were superparamagnetic at room temperature. We also have analyzed the potential of these particles for hyperthermia by determination of the specific absorption rate, the temperature increase (ΔT) of the particles was 37oC. These ferrofluids with high self-heating capacity are a promising candidate for cancer hyperthermia treatment.