پوشش دهي نانو ذرات مغناطيسي Fe304 و بررسي اثر پوشش ها براندازه و خواص مغناطيسي نانوذره

چكيده انگليسي :

AbstractNanosized particles have physical and chemical properties that are characteristic of neither the atom nor thebulk counterparts Quantum size effects and the large surface area of magnetic nanoparticles dramaticallychange some of the properties and exhibit superparemagnetic phenomena A particle of ferromagneticmaterial bellow a critical particle size would consist of a single domain The magnetization behavior ofthese particles above a certain temperature Blocking temperature is identical to that of atomicparamagnets super para magnetism except that an extremely large moment and thus large susceptibilitiesare involved Superparamagnetic iron oxide nanoparticles SPION with appropriate surface chemistryhave been widely used in numerous biomedical applications such as magnetic resonance imaging contrastenhancement drug delivery cell separation and hyperthermia All these biomedical and bioengineeringapplications require that these nanoparticles have high magnetization values and size smaller than 100 nmwith overall narrow particle size distribution so that the particles have uniform physical and chemicalproperties In the preparation and storage of nanoparticles in colloidal form the stability of the colloid is ofutmost importance Since particles are attracted magnetically in addition to the usual flocculation due toVan der Waals force surface modification is often indispensable For effective stabilization of density forcoating is desirable In these study magnetite nano particles magnetite particles Fe3O4 with a size under100 nm were prepared by the modified controlled chemical co precipitation method from the solution offerrous and ferric mixed salt solution in alkalin medium In the process of synthesis several coats added tonanoparticles and their effects on the magnetic properties of the nano particles were studied We studiedsurface derivatization of magnetite by fatty acids oleic acid linoleic acid and palmitoleic acid and onepolymer starch These coats are biocompatible and are chemisorbed on the surface of the nanoparticles which makes the particles hydrophobic thus they become dispersible in nanopolar solvents for biomedicalapplications The magnetit nanoparticles were characterized by x ray diffraction analysis XRD the XRDspectra of coated iron oxide nanoparticles exhibited peaks that correspond magnetite Fe3O4 Wedetermined the size and size distribution for samples by SEM images and by particle size analyzer ZETA SIZER The mean magnetice diameter was less than 100 nm our samples show in the absence any surfacecoating magnetic iron oxide particles have hydrophobicsurfaces with a large surface area to valume ratio Due to hydrophobic interactions between them and show ferromagnetic behaviour TGA Thermogravimetric Analysis was performed to analyze the surface characteristic of the nanoparticles The TGAindicated chemisorptions of coats at the iron oxide nanoparticle surface TGA derivative curves show twodistinct transitions for all of the samples the temperature of the first weight loss is approximately theboiling or decomposition temperature of the neat coat The enthalpy of the second higher temperature weight loss peak is significantly larger than that of the first weight for all samples An estimate of theaverage number of coat molecules on a particle was obtained from the area of the second weight loss peakrelative to the final residual sample weight The magnetic properties of the resultant Fe3O4 nanoparticleswere measured with a vibrating sample magnetometer VSM Quantum Design at room temperature Datasshow that our samples are superparmagnetic with no coercivity and remanence The saturationmagnetization of nanoparticles is much lower than the typical value 93 emug 1 for bulk materials Thedecreased for nanoparticles is attributed to the disordered surface spins Key words nano particle magnetite superparamagnetic hyperthermia

روحاني ، فرشته

پوشش دهي نانو ذرات مغناطيسي Fe304 و بررسي اثر پوشش ها براندازه و خواص مغناطيسي نانوذره

نانو ذرات مگنتيت , سوپر پارامغناطيس , هايپرترمي , پالميتولئك اسيد , لينولئيك اسيد