Biocompatible magnetic polymer carriers for in vivo radionuclide delivery

The magnetic guidance of antiplastic and antibacterial agents as well as x- ray and MRI contrast substances in vivo by means of magnetic particles has been attempted repeatedly during the last 2 decades with more or less succe ss. When using microparticles, the circulation time in the blood, the biodi stribution, and to a greater or lesser extent, the specific targeting are d etermined by the uniformity of size, chemical composition, surface modifica tion, and the electric surface charge. The electrophoretic mobility is an i mportant parameter for the prediction of the usefulness of the prepared par ticle, modified by chemical and biological molecules. For its success, radi onuclide therapy depends on the critical relationship between the amount of radioactive isotopes in the target tissue and in critical normal tissue. B ecause the implementation of radioimmunotherapy for the treatment of cancer has proven to be considerably more difficult than initially anticipated, w e propose the use of magnetic nanospheres for the well directed delivery of radionuclides to a tumor after the intravenous administration of the biode gradable colloidal suspension.