Combined hydrophobic and electrostatic interaction-based recognition in molecularly imprinted polymers

Molecularly imprinted polymers selective for D- and L-phenylalanine have been prepared in water solution using 2-acryloylamido-2,2'-dimethylpropane sulfonic acid and bisacryloyl beta-cyclodextrin as functional monomers, and N,N'-diacryloylpiperazine as cross-linker. Polymer-ligand recognition was evaluated using a combination of HPLC, displacement chromatography and fluorescence spectroscopic studies. HPLC studies revealed that the imprinted polymers possess optimal ligand selectivity in 30% water solution in acetonitrile. The results demonstrate that a balance of hydrophobic and electrostatic interactions is required for ligand recognition by these polymers. The imprinting effect is sufficiently strong to reverse the inherent chiral selectivity of the cyclodextrin molecule.