Conformational studies of common protein templates in macromolecularly imprinted polymers

Unlike the molecular imprinting of small molecule templates, molecularly imprinted polymers specific to large templates (> 1,500 Da), have achieved limited success to date. Conformational stability of these labile macromolecules is one of the main factors that prevent the direct extension of successful procedures from the small molecule regime. We continue our systematic investigation of the effect of common components in macromolecular MIPs on the conformation of protein templates. Circular dichroism was used to show that frequently employed monomers and crosslinkers induce significant changes in the secondary structures of lysozyme and bovine hemoglobin. The extent to which this change occurs, at ligand concentrations far below what are typically used reported work, is cause for concern and provides as rational explanation for the lack of success in this arena. This is because a change in the template structure prior to polymerization would lead to the binding sites formed during polymerization to be specific to this alternate conformation. Subsequent studies with the macromolecule in its native state and the crosslinked network would not be successful. Using this information as a guide, we offer suggestions as to where work in macromolecular imprinted polymers should focus going forward in order for these antibody mimics to reach their vast potential as a new class of biomedical diagnostic devices.