Synthesis and Characterization of MgFe204 Ferrite Nanoensemble for Biomedical Application

Abstract

Magnetic nanoparticles have drawn tremendous attraction from both fundamental aspect as well as applications in biomedicine such as magnetic bio-separation, detection of biological entities, magnetic resonance imaging, magnetic fluid hyperthermia and targeted drug delivery due to their fascinating magnetic properties. Superparamagnetic nanoparticles have become the focus of this study because their superparamagnetic, biocompatible and hydrophilic properties would be revealed after modifying the particle surface by suitable surfactants. Considerable research in this area has provided valuable in sites; however, suitable magnetic materials that can be fulfill all the requirements of MRI and hyperthermia applications are still under investigation. This thesis reports on an investigation into the synthesis, control, and stabilization of high quality magnesium ferrite nanoparticles for biomedical application. A new understanding of the factors effecting nanoparticle growth in a coprecipitation methodology has been determined. Then the ferrimagnetic MgFe204 r nanoparticles were modified by annealed temperature from 200 to 1400°C using box furnace. The crystal structural, mean particle size and magnetic properties of the modified ferrimagnetic MgFe204 nanoparticles were measured to investigate the effect of each process on the synthesized nanoparticles. The structural, morphological, magnetic properties of these synthesized products were characterized by using X-ray diffraction (XRD), Vibrating sample magnetometer (VSM), Mössbauer spectroscopy and NMR analysis. XRD patterns of as-dried powder yielded single phase. No impurity peaks were detected. With the increase of annealing temperature, the width of peaks decreases which reflects the coarsening of particles. The smallest crystallite size about 3 nm was obtained for as-dried sample while the largest value 71.86 nm was obtained from the highest studied temperature 1400°C. The crystallite size of the nanoparticles abruptly increased with the annealing temperature. Magnetization measurements have been accomplished by VSM. It was found that saturation magnetization increases with the increase particle size. The small particles first exhibit superparamagnetic behavior at the early stage and then transform to ferromagnetic behavior when particle size passes the superparamagnetic limit. Interesting experimental results on the size dependent magnetic properties at different temperatures have been found. Other structural and magnetic properties such as chemical isomer shift, quadruple splitting and hyperfine IL field were determined by Mössbauer spectroscopy. Superparamagnetic/ferromagnetic transition with the increase of particle size has also confirmed by this analysis. Mössbauer spectroscopy measurements are shown to evidence collective inter-particle correlations between the nanoparticles. The magnesium ferrite nanoparticles were then coated with biocompatible Chitosan (CS) and Polyethylene glycol (PEG). NMR spectroscopy was studied to investigate the spin-spin or T2 relaxivity values to determine its applicability in magnetic resonance images as MRI contrast agents.