Corinne Nardin

Nanoreactors based on (polymerized) ABA-triblock copolymer vesicles

A new kind of nanoreactor has been prepared by the incorporation of a channel protein into the shell of (polymerized) vesicles formed from an amphiphilic ABA-triblock copolymer.

Controlling membrane permeability with bacterial porins: application to encapsulated enzymes.

Recent achievements of membrane protein science allow easy protein modification by genetic engineering and, for some proteins, their production in large quantities. We regard these features as the basic requirements for applications of membrane proteins in materials science. Here, we demonstrate a possible application of membrane proteins, inserting porins from the outer cell wall of Escherichia coli into the walls of liposomes. Encapsulation of enzymes into liposomes or polymer nanocapsules protects them against proteases and denaturation. Functional reconstitution of porins into the capsule shell allows to control the rate and selectivity of substrate permeation, and thus to control the enzyme reaction kinetics. We suggest that this technique can prove to be useful in the area of biosensors, providing enzymatic stability while keeping the functionality or even enhancing the sensitivity by substrate preselection. Another application of this kind of stabilisation is in the field of single enzyme activity recording.

Hybrid materials from amphiphilic block copolymers and membrane proteins.

Self-assembly of reactive amphiphilic block copolymers is used to prepare nanostructured hydrogels with exceptional permeability properties, vesicular structures and planar, freestanding membranes in aqueous solution. Although the underlying block copolymer membranes are two-three-fold thicker than conventional lipid bilayers, they can be regarded as mimetic of biological membranes and can be used as a matrix for membrane-spanning proteins. Surprisingly, the proteins remain functional, despite the extreme thickness of the membranes and even after polymerization of the reactive block copolymers. The unique combination of block copolymers with membrane proteins allows the preparation of mechanically stable, defect-free membranes and nanocapsules that have highly selective permeability and/or specific recognition sites. This is documented by some representative examples.

Ion-carrier controlled precipitation of calcium phosphate in giant ABA triblock copolymer vesicles

An ionophore assisted metal-ion transport across block copolymer membranes has been used to control the local Ca2+ concentration during precipitation of calcium phosphate in giant block copolymer vesicles.