Amphiphilic block copolymer nanocontainers as bioreactors |
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Authors: | C Nardin J Widmer M Winterhalter W Meier |
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Institution: | (1) Department of Physical Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland, CH;(2) Institut de Pharmacologie et de Biologie Structurale, CNRS, 205 route de Narbonne, F-31077 Toulouse, France, FR |
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Abstract: | Self-assembly of an amphiphilic triblock copolymer carrying polymerizable end-groups is used to prepare nanometer-sized vesicular
structures in aqueous solution. The triblock copolymer shells of the vesicles can be regarded as a mimetic of biological membranes
although they are 2 to 3 times thicker than a conventional lipid bilayer. Nevertheless, they can serve as a matrix for membrane-spanning
proteins. Surprisingly, the proteins remain functional despite the extreme thickness of the membranes and that even after
polymerization of the reactive triblock copolymers. This opens a new field to create mechanically stable protein/polymer hybrid
membranes. As a representative example we functionalize (polymerized) triblock copolymer vesicles by reconstituting a channel-forming
protein from the outer cell wall of Gram-negative bacteria. The protein used (OmpF) acts as a size-selective filter, which
allows only for passage of molecules with a molecular weight below 400 g mol-1. Therefore substrates may still have access to enzymes encapsulated in such protein/polymer hybrid nanocontainers. We demonstrate
this using the enzyme β-lactamase which is able to hydrolyze the antibiotic ampicillin. In addition, a transmembrane voltage
above a given threshold causes a reversible gating transition of OmpF. This can be used to reversibly activate or deactivate
the resulting nanoreactors.
Received 22 August 2000 |
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Keywords: | PACS 83 70 Hq Heterogeneous liquids: suspensions dispersions emulsions pastes slurries foams block copolymers etc – 81 05 Ys Nanophase materials – 87 68 +z Biomaterials and biological interfaces |
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