CRC TRR 61 B11 - Molecular imprinting in polyelectrolyte multilayers and complexes

Basic data for this project

Description

In the present period, project B11 combines layer-by-layer (LbL) self-assembly of polyelectrolytes with the concept of molecular imprinting to achieve the fabrication of surface molecular imprinted LbL thin films (SMILbL), which have fast and selective binding properties for distinct guest molecules. The surface imprinted multilayers are fabricated from a polyelectrolyte with cross-linkable groups and a polyelectrolyte, which can be pre-complexed with the template molecule. In this period we could successfully elucidate the mechanism of electrostatic release and re-binding of charged guest molecules, apply SMILbL films in porous membranes to yield enhanced filtration properties, broaden the range of interactions to include H-bonds, and finally transfer the SMILbL concept from planar films to surfaces of colloidal particles to enhance the surface area. Future work will focus on two novel development lines: In order to develop new building blocks, new driving forces, and new functions, supramolecular amphiphiles will be systematically employed in SMILbL films. This will enhance the variety of interactions and thus of template molecules which can be employed in molecular imprinting in combination with LbL assembly. Furthermore, the introduction of supramolecular amphiphiles is anticipated to yield surface-imprinted films with higher loading capacity of template molecules. In addition, employing stimuli-responsive building blocks may lead to smart control over the binding interaction. Supramolecular amphiphiles with tunable properties, i.e. bola-form supramolecular amphiphiles which can assemble and disassemble conveniently will be employed. It is anticipated that these developments will improve the concept of molecular imprinting by avoiding its main limitations, which is the low efficiency caused by the previous ways of either template molecule and polymer chain aggregation in solution, or the low grafting ratio of template molecules to the polymeric constituents. As a further enhancement of the efficiency of imprinting, the concept will be transferred to nanoparticle structures. With block-copolymers as building blocks in combination with the previously established methods of templating, the number of imprinting sites can be enhanced. Defined, monodisperse nanoparticles with a core containing the imprinting sites and a stabilising shell can form a compromise between common bulk molecular imprinted polymers with a low accessability of imprinted sites, and thin films with a low density of the imprinted sites. Previously employed templating concepts in SMILbL such as electrostatic interaction or H-bonds as well as the novel concepts of supramolecular amphiphile imprinting will be transferred to defined nanoparticles, not only to further optimize the efficiency, but also to broaden the range of applicable methods to volume studies by NMR and ITC.