"In the production of fine chemicals the downstream processing may amount up to 75 % of the total manufacturing costs, particularly when the product is aimed at nutritional or therapeutic use which demands a maximum purity. Current downstream processing strategies can face limitations whenever existing purification and separation processes are based on physico-chemical principles and thus exhibit a far more limited selectivity for the target compounds than is known from interactions involving biomolecules. The latter, on the other hand, are less robust and often require specific operating conditions (typically close to ambient) and feed compositions, which often restricts their broad application. This proposal presents an innovative, interdisciplinary approach on designing selective and tuneable interfaces for sensors and separations to be employed in downstream processing techniques. By combining recent advances in biology/biochemistry and chemistry and applying them to chemical engineering principles, the approach goes beyond concepts currently known, involving primarily engineered nucleic acids (aptamers) and tuneable ionic liquids (IL) incorporated in an appropriate support structure. The aim of this proposal is to make use of the unique properties of both biomolecules and ionic liquids in order to create supported mixed-matrix interfaces which exhibit properties that bulk materials can hardly achieve. Another novelty of this proposal is the aim to develop these interfaces in a modular way, namely by joining individually optimised elements during interface design in order to yield the desired overall properties. This approach warrants a maximum of degrees of freedom in the overall interface design while keeping the basic interface architecture constant, and thus overcomes one of the limitations that many conventional separation/purification techniques encounter during optimisation of the bulk material."