Magnetic molecularly imprinted polymer beads for drug radioligand binding assay

Molecularly imprinted polymer-magnetic iron oxide composite materials which exhibit recognition properties and can be withdrawn from solution by application of a magnetic field were prepared for the first time. Magnetic iron oxide was incorporated using a suspension polymerisation methodology with a perfluorocarbon liquid as the dispersing phase for the preparation of methacrylic acid-1,1,1-trimethylolpropane trimethacrylate copolymer beads molecularly imprinted with the beta-blocker (S)-propranolol. The resulting superparamagnetic imprinted polymer beads were capable of binding [3H]-(S)-propranolol more strongly than a non-imprinted, otherwise identical, polymer. In a competitive radioligand binding assay using a magnet to separate polymer from solution, (R)-propranolol and (R,S)-metoprolol exhibited cross-reactivities of 19 and 0.7%, respectively, compared with (S)-propranolol.