Biophysical Society Thematic Meeting | Ascona, Switzerland

Liposomes, Exosomes, and Virosomes: From Modeling Complex Membrane Processes to Medical Diagnostics and Drug Delivery

Wednesday Speaker Abstracts

Biomimetic Block Copolymer Membranes Wolfgang Meier . University of Basel, Basel, Switzerland.

Similar to conventional lipids, suitable amphiphilic block copolymers self-assemble in aqueous media to membrane-like superstructures. The physical properties of these membranes can be controlled to a large degree via the chemical constitution, the molecular weight and the hydrophilic-to-hydrophobic block length ratio of these polymers. Compared to conventional low molar mass building blocks (e.g. lipids), membranes based on amphiphilic copolymers self- assembly, have both the advantage of superior stability and toughness, and offer various possibilities of tailoring physical, chemical and biological properties by multifunctionality, which can be implemented in one single macromolecule. Well-defined functions such as molecular recognition, cooperativity, regulation, replication, catalysis and antibiotics can be introduced by combining these synthetic superstructures with suitable functional units from Nature, e.g., by incorporation of integral membrane proteins or encapsulation of enzymes. By introducing appropriately functionalized polymers we succeeded to immobilize intact block copolymer vesicles or induce the formation of planar block copolymer membranes on solid support. Interestingly by Fluorescence Correlation Spectroscopy we could quantify the lateral mobility of block copolymer molecules as well as inserted proteins inside the block copolymer membranes. In comparison to biological phospholipid membranes the block copolymer membranes indicate systematic differences in mobility. In addition systematic experiments indicate that mixtures of phospholipids and block copolymers can form membranes in aqueous media consisting of phase separated phospholipid and block copolymer domains. Depending on their composition, the thickness of the polymer and/or phospholipid domains and their viscosity, we observed a systematic influence on insertion of proteins into a preferred domain and their local mobility.

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