Size and Magnetization Control of Magnetite NPs via Ethylene Glycol and Temperature for Ferrofluid and Magnetotargeting: Model Experiments

Abstract

Magnetic nanoparticles (NPs) are highly promising materials for diverse biomedical applications, particularly in magnetotargeting, owing to their tunable magnetic properties. Achieving precise control over their synthesis parameters is critical for optimizing these properties and ensuring their efficacy. This study investigates the impact of synthesis conditions on the properties of magnetite (Fe3O4 ) nanoparticles. A set of magnetite NPs were prepared via co-precipitation of ferrous and ferric ions by a base in ambient conditions, systematically varying the ratio of ethylene glycol/water (EG/water) solvents and temperatures (4, 20, and 70 °C). Crystal structure, morphology and magnetic parameters were analyzed. Additionally, rheological experiments were conducted to study the dynamic viscosity of ferrofluids containing varying sizes and concentrations NPs in polyglucinum. Results showed that Fe3O4 NPs size linearly increased with the EG/water volume ratio only at 70 °C. Increasing EG from 0 % to 50 % elevated magnetite stoichiometry from Fe2.72O4 to Fe2.912O4 with higher concentrations reducing it. The effect of temperature on stoichiometry varied depending on the ethylene glycol (EG) content. At low EG content, stoichiometry decreased with increasing temperature. But, at higher EG content, maximum stoichiometry was observed at 20 °C. Increasing polydispersity of NPs (0.07– 0.13) decreased viscosity in polyglucinum from ~10 to ~4 mPa s (1–5 % EG). Evaluation tests of the magnetic induction gradient on NPs capture in a flow-through setup were also performed. A sigmoidal relationship (R 2 = 0.97) was established between the NPs capture efficiency and the magnetic induction gradient. These findings provide valuable insights for optimizing the synthesis and suspension performance for magnetic fluids for magnetotargeting applications.