Design at nano-scale. biomimetic block copolymers for polymer-protein hybrid materials

In this thesis, the synthesis and applications of biomimetic amphiphilic ABA triblock copolymers are discussed. Polydimethylsiloxane hydrophobic middle block was synthesized and end-functionalized. Hydrophilic poly-2-methyl-2-oxazoline blocks were polymerized onto the PDMS macroinitiator, in symmetric cationic ring opening polymerization reaction. The end-groups of the synthesized block copolymers were further functionalized with biotin and methacrylate groups. Block copolymers were designed to self-assemble into vesicular structures in dilute aqueous solutions and the properties of the resulting membranes were tuned by the molecular weight of the hydrophobic blocks and the hydrophilic to hydrophobic ratio. Membranes built from the synthesized triblock copolymers were used to mimic the properties of natural lipid bilayers providing higher stability.
Block copolymer membranes were reconstituted with a number of natural membrane proteins, thus introducing biological activity and functionality to synthetic materials. Insertion of a bacterial Aquaporin-Z channel protein into water (and solutes) impermeable polymeric membrane resulted in novel hybrid materials promising great improvement in the area of water purification. High impermeability and stability of the triblock copolymer membranes provided an excellent tool to investigate the influence of environmental conditions on transport properties of Aquaporin-Z. Combining the outer membrane protein F - reconstituted polymer vesicles, encapsulating water-soluble enzymes, with receptor-ligand mediated immobilization resulted in an development of immobilized polymeric nanoreactors system. Its potential relevance is in the field of microfluidics, sensors and single molecule spectroscopy, as well as basic research on sensitive molecules and chemically/biologically active surfaces. Block copolymer membranes, in combination with a complex membrane protein, NADH: Ubiquinone Oxidoreductase, were used in the design of the electron -transfer nanodevice that allows site-specific reactions driven by redox-potential differences. Vesicular morphology of aggregates formed by triblock copolymers in dilute aqueous solutions was also utilized in the studies towards potential applications as a drug delivery platform. Interactions of block copolymers with lipids of different properties are also discussed. The structure of the thesis guides the reader through a general introduction to amphiphilic materials, their selfassembly properties and applications (Chapter 1). Polymer-protein hybrid materials are introduced together with membrane proteins used in this work (Chapter 1). The experimental part is divided into two sections: the first describing synthetic routes and characterization of the block copolymers, and the second in the form of original publications, presenting applications of the block copolymers (Chapter 2). Conclusions drawn from our experiments are presented in Chapter 3 and the outlook of our work is outlined in Chapter 4. Information about the materials and methods used and not presented in original publications is shown in Chapter 5 and literature references listed in Chapter 6.