Magnetic ferrofluids for preparation of magnetic polymers and their application in affinity chromatography

THE use of magnetic polymers as supports for biological molecules has created much interest1–5. The inherent advantages of such preparations are, in particular, the ease of recovery of these polymers by applying a magnetic field. Thus, when used as supports for immobilised enzymes, their easy retrieval from liquors containing colloids or undissolved solids should be of great practical value1–3. Magnetic polymers have recently been tested as an alternative to conventional radioimmunoassay technique, obviating the need for vertical rotation and for the time-consuming, multiple centrifugations required with conventional solid phase procedures4–5. In the established techniques for producing magnetic polymer particles, the attachment of the biomolecules had to follow the preparation of the specific magnetic material; furthermore most of these preparations have been non-porous, exhibiting rather poor capacity. We describe here a novel and general procedure using magnetic fluids which allows ‘post-magnetisation’ of polymers already substituted with biological molecules. The properties of such preparations have been tested primarily as affinity chromatography gels. These preparations showed unaltered biospecificity when applied in general ligand-affinity chromatography studies. The simplified separation possible due to the magnetic properties of the gels eliminates the usual centrifugation and column chromatography steps. The procedure of ‘post-magnetisation’ seems to be suitable for different polymer particles, both unsubstituted gels and those carrying immobilised ligands as affinity adsorbents or enzymes.