Magnetit nanoparçaciklarinin biyomimetik sentezi, manyetik özellikleri ve uygulamalari

Iron oxides are one of major classes of inorganic compounds widespread in nature and important for many disciplines. As a member, magnetite is one of the most studied naturally occurring mineral owing to its excellent magnetic and biocompatible properties. Magnetite nanoparticles are also suitable for several applications where their effective use depends on corresponding size, shape thus magnetic properties and stability of the particles. Although it is a challenge to take control over magnetite morphology without use of high temperatures and complicated synthesis pathways, the synthesis of magnetite nanoparticles through partial oxidation of ferrous hydroxide precursor at biomimetic conditions, i.e. at room temperature and in water, demonstrated the possibility of growth regulation as a result of interaction with a soluble poly(amino acid). As the stability of magnetite nanoparticles in aqueous medium is essential for several applications such as drug delivery, heat transfer and magnetic hyperthermia, the nanoparticles in the superparamagnetic and ferrimagnetic domains synthesized through co-precipitation and partial oxidation were functionalized with poly(ethylene imine)-graft-poly(oligo(ethylene glycol methyl ether) and poly(acrylic acid) respectively. The stability achieved in aqueous medium by using these polymers made the polymer-magnetite complexes suitable for various applications. As it is known from the literature, these nonmagnetic coatings may form a magnetically disordered layer on the nanoparticles which reduces the total amount of the magnetic phase. For this purpose, reduction of magnetic phase was studied for similar amine and carboxylic acid functionalized magnetite nanoparticles. Results indeed showed a reduction in the magnetic phase for both coatings which highlight again the necessity of considering this reduction for optimizing the magnetic properties of magnetite nanoparticles. Finally, the effect of superparamagnetic magnetite nanoparticles on the thermal conductivity of water was investigated. The contradictory results showed deteriorations in the thermal conductivity of water upon addition of magnetite nanoparticles which was independent of the synthesis method, the type of surfactant used and the interfacial thermal resistance.