Functional microgel systems
The research in projects C3 to C6 aims at the design of functional microgel systems for dedicated applica-tions (Fig. 16). The applications range from controlled uptake in medical applications, over separation and extraction processes, to organocatalysis. A common feature of these functional microgel systems is that microgel properties such as size, architecture, sensitivity to environment, and functional groups providing interaction with the surroundings, determine the properties of the application system, such as transport properties, separation and catalytic efficiency. On the one hand the application examples prove the versatility of functional microgel systems; on the other hand they form an important driver for the further development of functional microgels and for the understanding of microgel structure – function relationships.
Project C3 develops microgels to remove toxins originating from Clostridium difficile infection from the gas-trointestinal tract. In the 1st funding period, Galili-functionalized microgels that specifically bind the toxin TcdA were developed. In the next funding period, the project will introduce novel bifunctional microgels with high binding affinity towards TcdA and a second toxin TcdB. An additional functionality will be introduced to the microgels, namely the capability to cleave – and thereby inactivate – the toxins. The overall aim of the project is to develop microgels that neutralize C. difficile toxins in vitro and in vivo, efficiently protect mice from experimental CDI and that will be potential candidates for clinical testing in the future.
C4 aims at using microgels for the molecular separation based on electrostatic interactions. In the first funding period, the synthesis of charged microgels with tunable size, cross-linking density and charge and the preparation of ordered monolayer patterns of cationic and anionic microgels on membrane surfaces were established. The emphasis of the 2nd period will be on pattern formation (loosely packed layers, mesoscopically-patterned heterostructures, and more complex topologies), the integration into membrane architec-tures and the characterization of their ion transport properties. With the understanding on ion transport es-tablished for precisely tuned and laterally homogeneous membrane/fluid interfaces, the second period will also explore the ion transport through homogeneous microgel interfaces as well as laterally heterogeneous patterned microgel interfaces.
The new project C5 will investigate microgels for the intensification of extraction processes to improve the performance and operational flexibility of extraction processes. The project builds on knowledge on microgel-stabilized emulsions gained in project C1. The investigations in this project will combine mesoscopic and microscopic approaches, leading to better understanding of the behavior of microgels at the liquid-liquid interface and mass transport across the interface. Fluorescence-microscopy methods – such as single microgel tracking and superresolved localization microscopy – will elucidate microscopic phenomena. On a mesoscopic scale, single-drop experiments will be performed to analyze the influence of microgels on mass transfer and sedimentation behavior under conditions close to real extraction processes. The results will be used to extend established extraction-column models and to enable the simulation of microgel-supported extraction processes. This will enable the model-based design of intensified extraction processes in the long term.
The new project C6 focuses on the synthesis of enzymeinspired microgel-based catalysts (microgelzymes) and investigation of their properties for applications in liquid-phase conversion processes. The incorporation of organocatalysts, design of binding sites as well as the control over their spatial distribution and local chemical environment in the microgel network will determine the performance of microgelzymes in different catalytic processes as, e.g., desymmetrisation of anhydrides or C-C coupling in a simultaneous or sequential fashion.