Sonochemical synthesis of versatile hydrophilic magnetite nanoparticles

Hydrophilic magnetite nanoparticles in the size range 30–10 nm are easily and rapidly prepared under ultrasonic irradiation of Fe(OH)2 in di- and tri-ethylene glycol/water solution with volume ratio varying between 7:3 and 3:7.Structural (XRD) and morphological (SEM) characterization reveal good crystalline and homogeneous particles whereas, when solvothermally prepared, the particles are inhomogeneous and aggregated. The sonochemically prepared particles are versatile, i.e. well suited to covalently bind molecules because of the free glycol hydroxylic groups on their surface or exchange the diethylene or triethylene glycol ligand. They can be easily transferred in hydrophobic solvents too.Room-temperature magnetic hysteresis properties measured by means of Vibrating Sample Magnetometer (VSM) display a nearly superparamagnetic character.The sonochemical preparation is easily scalable to meet industrial demand.

► Crystalline, homogeneous magnetite nanoparticles are rapidly sonochemically prepared.
► The magnetite nanoparticles are hydrophilic, dispersable in ethanol/water mixtures.
► The magnetite nanoparticles can be easily transferred in hydrophobic solvents.
► The nearly superparamagnetic nanoparticles slowly approach saturation at high fields.