PREPARATION AND MAGNETIC PROPERTIES OF VERY SMALL MAGNETITE-DEXTRAN PARTICLES

摘要

The present invention is directed to particles comprised of a magnetically responsive material and a dispersant, said particles having a particle size range of about 2 to about 10 nm. The present invention is also directed to a method for the preparation of such particles comprising admixing a magnetically responsive material with a dispersant to form an admixture, and contacting said first admixture with a base for a time period and under conditions appropriate to form a magnetically responsive material-dispersant particle. In a preferred embodiment, the magnetically responsive material is magnetite, the dispersant is dextran, and the base is ammonium hydroxide. In a further preferred embodiment, the admixture is suspended in a gel phase. The present invention is further directed to a method of diagnosis comprising administering to a mammal a contrast effective amount of these particles suspended or dispersed in a physiologically tolerable carrier and generating an NMR image of said mammal.