Use of fluorescence shift and fluorescence anisotropy to evaluate the re-binding of template to (S)-propranolol imprinted polymers

Abstract

The binding of (R)- and (S)-propranolol to an (S)-propranolol imprinted polymer in organic and aqueous solutions has been studied using fluorescence. The amount of propranolol that binds can be measured by separating non-bound propranolol from the polymer by centrifugation, and measuring the fluorescence intensity. However, this work demonstrates that other measurements can indicate how much propranolol has bound without the need to separate bound and non-bound analyte. In toluene + 0.5% AcOH, and in aqueous buffer (25 mM citrate pH 6 + 0.5% Triton X100) the fluorescence anisotropy increases as the fraction of analyte bound to the polymer increases. In aqueous buffer, binding to the polymer is also accompanied by a change in the relative intensities of fluorescence at 322 nm and at 352 nm. These non-separation techniques have been used to show that the imprinted polymer binds more (S)-propranolol than a non-imprinted polymer, and at least in organic solvent, shows selectivity for (S)- over (R)-propranolol.