engleski

γ-irradiation synthesis of magnetic iron oxide nanoparticles in the presence of different dextran polymers

Magnetic iron oxide nanoparticles (NPs) have applications as sensor, as contrast agents for MR imaging, in drug delivery and for hyperthermia cancer treatments. γ-irradiation is an attractive and ecologically friendly technique for the synthesis of magnetic nanoparticles at room temperature. It has an advantage of inducing electrons and other reducing species homogeneously through the sample. Unlike radiolytical synthesis of noble metal NPs, the radiolytical synthesis of iron oxide NPs is much less investigated. One of the reasons is very complex iron oxide chemistry that produced numerous phases. Besides, magnetic NPs have a high tendency for agglomeration and due to this reasons various polymers are used that act as dispersants and stabilizers of magnetic NPs in suspensions as well as growth and surface modifiers. Herein, we studied the influence of γ-irradiation dose, dose rate, pH and type of dextran polymers on the magnetic iron oxide NPs synthesized using γ-irradiation. In order to achieve reducing conditions upon γ-irradiation iron(III) chloride alkaline aq. solutions were purged with nitrogen in the presence of 2-propanol. Since ferrous ions (Fe2+) that formed upon γ- irradiation of iron(III) precursor (in the form of Fe(OH)2 and Green Rust intermediate phases) are highly susceptible to oxidation, the final product depend not only on the γ-irradiation parameters, but also on the process of product isolation. In the presence of positively charged DEAE-dextran polymer the irradiation with dose of 36 kGy resulted in formation of very small spherical substoichiometric magnetite NPs, whereas at higher dose (130 kGy) the magnetic delta-FeOOH nanodiscs were obtained. On the other hand, irradiation with 130 kGy in the presence of negatively charged dextran sulfate resulted in formation of mixed phases such as alpha-FeOOH, delta-FeOOH and iron(III) hydroxide sulfate. By admixing glycerol in irradiated suspensions reduced intermediated phases such as Fe(OH)2 and Green Rust were captured thus confirming that γ- irradiation generated reducing conditions. In addition, we quantitatively determined the concentration of Fe2+ produced in irradiated suspensions by spectrophotometric technique (using 1, 10-phenanthroline and ferrozine) as well as by redox titration using potassium permanganate, and compared these results with the amount of Fe(II) in isolated powders. Besides, the synthesized magnetic NPs were used for decolorization of methylene blue, a cationic organic dye which is used in color staining of domestic objects and in industry and which removal from industrial wastewater is of a major concern.

γ-irradiation ; iron oxides ; dextran polymers ; methylene blue

nije evidentirano