Chemical design of new functional microgels
Research area A focuses on the design of aqueous polymer microgels with new functionalities and their use as building blocks for complex architectures in bulk and at interfaces (Fig. 14). The projects aim at develop-ing microgels with functional compartments serving, e.g. as specific reaction environments for enzymes or for controlled uptake and release of (macro)molecules.
The potential of microgels to serve as building blocks for the design of hybrid suprastructures will be explored. The challenging task is to understand and control the complex switching mechanisms triggered by temperature, light, pH and electrochemical potential that will allow designing interactive microgel-based materials such as actuators, sensors, and release containers.
Projects A1 and A3 are mainly focused on the design of new microgel architectures that enable specific interaction of microgels with active guests. A6 is devoted to the surface-assisted generation of novel switchable microgel architectures and assemblies, while A7 develops a microgel self-oscillator driven by light. Future applications of the systems developed in these projects will depend on being able to control mass and energy transport and thus there are strong links to research areas B and C where these topics will be addressed.
Project A1 aims to improve the enzyme efficacy in specific organic reactions by coordination of two orthogonal strategies: (i) embedding and tethering enzymes to microgels and (ii) reengineering the enzyme structure. While in the first funding period the focus was put on the lipase Candida anarctica lipase B, CalB, to enable ester formation in aqueous dispersions, future emphasis aims also at a tandem reaction in which the monooxygenase P450 BM3 is used to hydroxylate an aromatic halogen, e.g. iodobenzene, that can subsequently undergo C-O and C-C coupling catalysed by a copper scorpionate.
Project A3 addresses the design of amphoteric microgels with controlled spatial distribution of functional groups for uptake and release of charged molecules by means of experiments and computer simulations. Hollow microgels will be introduced as new structural motif.
Project A6 employs two approaches for the surface-assisted generation of novel switchable microgel architectures and assemblies. The first one comprises an electrochemical pathway and is based on the results of the 1st period. The second approach combines chemical e-beam lithography and confocal photolithography for the site-specific immobilization of oligonucleotide (DNA) single strands to nanoscopic spots. This part uses results from former project A5 and is further strengthened by modern optical techniques.
The new project A7 endeavors to develop a mesoscopic microgel-based clock. The principle of the clock involves the absorption of the light by metal nanoparticles embedded in the microgel. Its self-oscillatory periodic motion is fed with light energy from a continuous-wave laser source. The project builds on results obtained in former projects A4 and A5, but in addition a feedback mechanism based on self-modulation of the absorption will be developed.