Preperation and characterization of silica coated magnetite nanoparticles and labeling with nonradioactive Re as a surrogate of Tc-99m for magneticly targeted imaging

Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Faculty of Arts and Sciences, Department of Chemistry, Turkey

Approval Date: 2010

Thesis Language: English

Student: Ümit Zengin



Magnetic nanoparticles have been used in many areas owing to their variable characteristic behaviors. Among these iron oxide nanoparticles are one of the mostly preferred type of nanoparticles. In this study Fe3O4, namely magnetite, which is one type of magnetic iron oxide nanoparticles was used. Magnetite nanoparticles with a narrow size distribution were prepared in aqueous solution using the controlled coprecipitation method. They were characterized by electron microscopic methods (SEM and TEM), crystal structure analysis (XRD), particle size analyzer, vibrating sample magnetometer (VSM) and Raman spectrometry. The nanoparticles were coated with a thin (ca 20 nm) silica shell utilizing the hydrolysis and the polycondensation of tetraethoxysilane (TEOS) under alkaline conditions in ethanol. The presence of silica coating was investigated by energy dispersive X-ray spectrometer (EDX) measurement. After surface modification with an amino silane coupling agent, (3-Aminopropyl)triethoxysilane, histidine was covalently linked to the amine group using glutaraldehyde as cross-linker. Carbonyl complexes of rhenium [Re(CO)3(H2O)3]+ was prepared through reductive carboxylation utilyzing gaseous carbon monoxide as a source of carbonyl and amine borane (BH3NH3) as the reducing agent. The complex formation was followed by HPLC- ICP-MS system and 95% conversion of perrhanete into the complex was achieved. The magnetic nanoparticles were then labeled with the Re complex with a yield of 86.8% through the replacement of labile H2O groups with imidazolyl groups. Thus prepared particles were showed good stability in vitro. Herein rhenium was selected as a surrogate of radioactive 99mTc. However radioactive isotopes of rhenium (186-Re and 188 Re) is also used for radioactive therapy.