Abstract: Processes and compositions are provided for performing magnetibuoyant separations of different biomolecules (e.g., cells, organelles, etc.) in a biological sample, as well as compositions and kits for performing such methods. Compositions containing the separated biomolecules, and methods for using the same for in-vitro and in-vivo biomedical applications, are also provided. The magnetibuoyant methods of the invention employ targeted magnetic particles, preferably targeted nanomagnetic particles, and targeted buoyant particles such as buoyant microparticles and microbubbles. Among the benefits of the invention is the ability to combine targeted magnetic particles with differentially targeted buoyant particles to achieve separation of two or more specifically cell targeted populations during the same work flow.