New configurations and applications of molecularly imprinted polymers

Molecularly imprinted polymers (MIPs) are applicable in a variety of different configurations. For example, bulk polymers imprinted with p-lactam antibiotics are presented to be used as stationary phases for the chromatographic separation of p-lactam antibiotics with both aqueous and organic mobile phases. However, in some analytical applications, monosized spherical beads are preferred over the currently used ground bulk polymers. A precipitation polymerization technique allows preparation of monosized spherical imprinted beads with diameters down to 200 nm having excellent recognition properties for different target molecules. Nevertheless, with current imprinting protocols a substantial amount of template has to be used to prepare the polymer. This can be problematic if the template is poorly soluble, expensive or difficult to obtain. It is shown that for analytical applications, the functional monomer:template ratio can be drastically increased without jeopardizing the polymer's recognition properties. Furthermore, a substantial reduction of the degree of crosslinking is demonstrated, resulting in much more flexible polymers that are useful for example the preparation of thin imprinted films and membranes for sensors. Apart from analysis, MIPs also are applicable in chemical or enzymatic synthesis. For example, MIPs using the product of an enzyme reaction as template are utilized for assisting the synthetic reaction by continuously removing the product from the bulk solution by complexation. This results in an equilibrium shift towards product formation. (C) 2000 Elsevier Science BN. All rights reserved.