Shape and size controlled synthesis of FePt and Ferrite nanoparticles for bio-application

Abstract

Magnetic nanoparticles (MNPs) with uniform shape and size distribution have been the great importance in various fields of applications, including magnetic energy, data storage, magnetic separation, drug delivery and biology applications. On the same time controlling the shape and size of the nanoparticles will have a significant effect on its various properties and consequently the potential applications. Therefore, various approaches like sonochemical, polyol, hydrothermal synthesis, microemulsion, thermal decomposition, and co-precipitation method have been developed for the nanoparticles morphology control. Among these approaches, the thermal decomposition route is considered the most attractive method for synthesis of high crystalline and uniform particle size distribution. However, the extent of control over particle dispersion and morphology was not adequate for achieving particles useful in real applications. In this thesis, I present a facile, safe, and convenient thermal decomposition route for morphology controlled synthesis of two kinds of ferrite nanoparticles (Fe3O4 and CoFe2O4) and one kind of magnetic alloy nanoparticles (FePt) for using in bio-medical applications. For the ferrite nanoparticles, simple modification of the reaction condition, including temperature, time, solvent, surfactant, and precursor amount allowed us to isolate nanoparticles as cubes, hexagons and spheres ferrite NPs with broad sizes ranging. Oleic acid and oleylamine were used as the solvents, stabilizers, and reducing agents and iron(III) acetylacetonate and cobalt(II) acetylacetonate were successfully employed as precursors instead of commonly used toxic, flammable and expensive pentacarbonyl. On the other hand, for FePt alloy nanoparticles, we could control the Fe atomic composition in FePt particle and two kind of structure which are homogeneous FePt and heterodimer structure (FePt/Fe3O4). For controlling the FePt alloy nanoparticles, we found that both of the reducing agent and precursor molar ratio are important parameter. First, using 1,2-hexadecanediol, when precursor mole ratio (Fe:Pt) increase from 1:1 to 3:1, Fe composition also increased. However, there are no more increase of Fe composition when used 4:1 molar ratio and also the heterodimer structures of Fe3O4/FePt is formed. On the other hand, when 1-octadecene, was used, no hetero structure even over 4:1 molar ratio is formed and also the controlling of FePt atomic composition ratio is more easier than the case of using 1,2-hexadecanediol. Since the bio-compatibility is one of the important issues from the view point of practical bio-application, my thesis also focused on studying the effect of concentration of the synthesized FePt nanoparticles on the cytotoxicity of CCK-8 assay and Live/Dead cell through staining & confocal microscopy images. The cell survival rate increased with the culture days increased and concentration. 80% cell viability was maintained in less than 1000 μl/ml concentration and therefore the possibility for using our nanoparticles in the bio- application was confirmed from these data. ⓒ 2016 DGIST