Scintillation proximity assay using molecularly imprinted microspheres.

Molecularly imprinted microspheres were prepared as antibody binding mimics and used in scintillation proximity assay of a beta-adrenergic antagonist, (S)-propranolol. By using small polymer beads, we were able to place an organic scintillator and an "antenna" component in close proximity to the imprinted binding sites. When the radioactive template bound to the polymer, radiation energy was effectively transferred, via the antenna component, to the scintillator to generate a fluorescence signal. Using molecularly imprinted microspheres instead of antibodies, we have demonstrated competitive scintillation proximity assays for (S)-propranolol in both organic and aqueous solvents. The experimental results were further validated by normal ligand binding analysis, where liquid scintillation counting was used for quantification.