Protein Separations Using Colloidal Magnetic Nanoparticles

Phospholipid‐coated colloidal magnetic nanoparticles with mean magnetite core size of 8 nm are shown to be effective ion exchange media for the recovery and separation of proteins from protein mixtures. These particles have high adsorptive capacities (up to 1200 mg protein/mL adsorbent, an order of magnitude larger than the best commercially available adsorbents) and exhibit none of the diffusional resistances offered by conventional porous ion exchange media. Protein‐laden particles are readily recovered from the feed solution using high‐gradient magnetic filtration.