Effect of coating materials on lymph nodes detection using magnetite nanoparticles

Magnetite nanoparticles-based contrast agents used in magnetic resonance imaging has offered new promise for early detection of lymph nodes and their metastases. Beside the value of Magnetite core of superparamagnetic nanoparticles as an efficient contrast agent, the type of coating material is important for their biodistribution properties. In this study, various coating materials were synthesized and their detection sensitivities were evaluated in axillary lymph nodes. These nanoparticles were prepared in an aqueous-phase under ultrasonic irradiation. Four different types of coatings including polyethylene glycol, Dextran, Carboxymethyl Dextran, and double layer of PEG-Dextran were used as the capping agents. The crystal structure, morphology, hydrodynamic size and magnetic properties of the nanoparticles were characterized. In-vitro relaxivity measurements along with post contrast in-vivo studies on rat demonstrated that the synthesized nanoparticles are applicable as magnetic resonance imaging contrast agents for imaging of the lymph nodes. In-vitro magnetic resonance imaging showed the optimum r2/r1 for Dextran nanoparticles. The best contrast to noise ratio (CNR) for in-vivo studies was obtained by the Dextran-coated nanoparticles.