We are developing a novel, integrated system based on superparamagnetic, biocompatible nanospheres for selective and rapid decorporation of biological, chemical, and radioactive biohazards from humans. The system utilizes polymer-based magnetic nanospheres that are injected directly into the blood stream of biohazardexposed humans. The composition of the injected nanospheres is biodegradable polymers of lactic acid or lactide-glycolide. Since it is well recognized that systemic injection of naked polymer spheres will result in rapid bioclearance by the reticuloendothelial system, the surface must be coupled to long chains of polyethylene glycol. Magnetic iron oxide nanocrystals are encapsulated within the polymer. Receptors are terminally attached to the polyethylene glycol or encapsulated within the polymer sphere, depending on the application. In total, the chemical components of the spheres confer nontoxicity and biocompatibility, avoid rapid bioclearance, and are biostabilized temporarily. Once injected, the spheres circulate freely through the blood stream, selectively capturing blood-borne toxins to specific recep-