Synthesis of manganese oxide nanoparticles, characterizations and investigation of applicability in biomedical imaging techniques

In this thesis, three different manganese oxide structures were synthesized, which are used as a paramagnetic agent in order to increase the T1 relaxation rate in the magnetic resonance imaging (MRI) technique and in which applicability will be tested in the magnetic particle imaging (MPI) technique. MnO2, Mn2O3, Mn3O4 nanoparticles having controllable size and shape properties were obtained by using the hydrothermal method in rod, spherical and tetragonal geometry, respectively. Different temperature, time, amount of reducing agent and solvent were examined for the optimization of the experimental conditions. The Mn3O4 structure was produced and in pure form as a result of the heat treatment lasting at 180°C for 3 hours and MnO2 crystal structure was at 200°C for 3 hours. Mn2O3 nanoparticles were obtained as a result of high-temperature calcination of MnCO3 obtained at 80°C. The surfaces of the obtained pure structures were modified with polyethyleneimine, dextran and polyacrylic acid organic compounds in order to increase the colloidal stability, biocompatibility and test the usability in imaging techniques. Structure, morphology and magnetic properties were determined by various techniques before and after surface modification. The samples with the highest dispersion stability were selected and analyzes were made for their usability in magnetic resonance imaging and magnetic particle imaging techniques. In general, a significant increase was observed in the colloidal stability of dextran and polyacrylic acid coated manganese oxide samples compared to their pure form. Changes in the magnetization properties of nanoparticles whose surfaces were coated were reported. The highest r1 relaxation rate (Mn2O3@PEI2K) among the particles was found to be 0.17 mM-1s-1.