Preparation And Characterization Of Magnetic Nanospheres For In Vivo Application

New biodegradable magnetic nanospheres were synthesized for the application in the magnetic field assisted radionuclide therapy. For this purpose, superparamagnetic iron oxide cores were coated with several hydrophilic polymers, such as dextran, starch, chitosan, ficoll, polyethylene imine and polyvinylpyrrolidone. The different surface properties of these magnetic polymer nanospheres were demonstrated by a significant variation of the electrophoretic mobility of the particles in dependence on the pH-value.To ensure the complexation of radionuclides, typical chelating agents (citric acid, EDTA, DTPA, TTHA etc.) were covalently bound to the surface of the particles. Because of the short blood half-life time of such particles with highly charged functions on the surface, a further surface modification was undertaken with polyethylene glycol (PEG). Particle electrophoretic measurements indicate that the PEG tentacles surround the nanospheres and decrease the influence of the free carboxylic acid groups on the surface charge of the particles. This effect might prolong the half-life time of the particles in the blood.