Synthesis of nano-size magnetite coated with chitosan for MRI contrast agent by sonochemistry

Superparamagnetic iron oxide (SPIO) nanoparticles have been developed for clinical applications in magnetic resonance imaging (MRI) contrast enhancement. The particles were synthesized by a sonochemistry to control the particle size and get hold of narrow size distribution. The properties of such particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), VSM, and PSA. The in-vivo test was carried out with two New Zealand white rabbit to validate MR image enhancement effect and physiological toxicity. In this study, the hydro-particle size were controlled in the range 40∼80 nm at the ultrasonic exposure time for 60 min and ultrasonic power 30%. Magnetization curves of the magnetic particles at different ultrasonic exposure time showed that the particles behaved with superparamagnetism and the magnetization values increased with decreasing ultrasonic exposure time. It is for no other reason than that the crystal size became smaller at long ultrasonic exposure time. The prepared particles have a perfect crystal structure to ensure that the clear image can be gained in diagnoses. Such particles coated with chitosan can be used in medical diagnostic techniques and allow the noninvasive visualization by enhancement of T2 MRI images.