Molecular Recognition Within Imprinted PVA/PAA Hydrogels

Abstract

Molecular recognition is the ability of the molecule to selectively recognize a target molecule from the ensemble of related molecules using covalently or non-covalently forces. The most widely recognized system of molecular recognition is present in the immune system in the form of antigen/antibody recognition. Polymers which can specifically bind a target molecule (drug) can be of interest, e.g. as drug delivery devices. One method for the preparation of synthetic polymers with high specific recognition capabilities is the molecular imprinting. The production of molecular imprinted polymers (MIP) is based on the free-radical solution polymerization of functional monomers in the presence of a template molecule combined with a crosslinking agent. After the extractive removal of the template molecule, the polymer matrix with the 3D binding cavities remains showing complementary shape and functionality of the template molecule. Here, hydrogels prepared by the imprinting method, using poly(vinyl alcohol) and poly(acrylic acid), are presented. As a sample template molecule the ionic drug cefazolin and the non-ionic theophylin were used. To determine the performance of imprinted hydrogels, the effect of the pH change and the change of ion strength were investigated and the chemical character of the drug was considered. Characterized were the swelling properties and drug re-built ability within the polymer in aqueous solutions with different temperature, pH and ionic strength ranges. To describe the binding ability of the MIP, a model developed by Van Tassel et al. [1] was applied which is an extended quenched-annealed model of adsorption in porous materials.