Paper Title
The Effects Of Alkaline Reagent And Synthesis Atmosphere On The Chemical, Morphological, And Magnetic Characteristics Of Magnetite Nanoparticles For Hyperthermia Treatment

Abstract
This study investigated the simultaneous effects of two alkaline reagents including sodium hydroxide (NaOH) and ammonium hydroxide (NH4OH) as well as the aerobic and anaerobic (N2) atmospheres on the crystalline structure, zeta potential, aggregation vulnerability, magnetic characteristics, heating efficiency of iron oxide nanoparticles (IONPs) under hyperthermia condition. The obtained results indicated the crucial impact of the synthesis atmosphere on the crystalline structure and magnetic properties, while the alkaline reagent type mainly governed the zeta potential and particle morphology. Although the IONPs precipitated with NaOH under anaerobic environment exhibited higher zeta potential and thus slightly less aggregation vulnerability, those synthesized using NH4OH in anaerobic atmosphere provided enhanced crystallinity and magnetic properties. Therefore, due to the negligible effect of alkaline reagent type on the morphological characteristics of the nanoparticles, an anaerobic atmosphere with NH4OH as the precipitating agent was chosen as the optimal synthesis condition, resulting in particles with higher crystallinity and enhanced superparamagnetic properties. The temperature control in the secure range of magnetic hyperthermia therapy (MHT) was achieved by the variation of either the IONPs concentration in the aqueous solution or the field strength. The heating capability of the IONPs was also quantified by the specific absorption rate (SAR), and the intrinsic loss parameter (ILP). The SAR and ILP values were positively influenced by the field strength, while increase of the particles concentration resulted in reduced SAR and ILP, probably due to the reduced dominance of the heating loss mechanism. The IONPs with the lowest concentration of 1 mg.ml-1 and 14 nm crystalline size expressed the highest SAR value of 316.43 W.gFe-1.. Index Terms - Alkaline Reagent, Iron Oxide Nanoparticles, Magnetic Hyperthermia Therapy, Synthesis Atmosphere.