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Liposomes, Exosomes, and Virosomes: From Modeling Complex
Membrane Processes to Medical Diagnostics and Drug Delivery
Wednesday Speaker Abstracts
31
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.