Fine-tuning magnetic and hyperthermia properties of magnetite (Fe3O4) nanoparticles by using ammonia as a reducing agent

Abstract

The tunable control of heat produced by magnetic nanoparticles (NPs) when placed in an alternating magnetic field can prevent undesirable concurrent heating of healthy tissues for magnetic hyperthermia. Here, magnetite (Fe3O4) NPs are synthesized by a co-precipitation method with different concentrations of ammonia (CA = 7–30 ml) as a reducing agent. By changing CA, increasing and decreasing trends of structural, morphological and magnetic properties are observed. Superparamagnetic (SPM) behavior of Fe3O4 NPs is studied by first-order reversal curve analysis, indicating fine-tuned SPM percentages. By dispersing these NPs in water medium, specific loss power (SLP) is investigated. The variation of SLP as a function of CA is found to follow that of SPM percentage, reaching a maximum value of 93 W/g for a ferrofluid containing Fe3O4 NPs synthesized with CA = 23 ml. In this case, SPM percentage is maximized to about 60 %, facilitating the heat production by Néel and Brownian mechanisms.