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Résumé:

On the one hand, one of the scientific challenges in nanofiltration is to develop nanofilters with both high permeability and selectivity, which are often considered as antagonist features. Today, the number of solid state membranes that are readily useable is limited and their performances, i.e. permeability and selectivity, are restricted. New materials for nanofiltration are thus clearly requested. On the other hand, it is well known that ionic bio-channels insure ionic (Na+, K+...) exchange of living cells and that their properties in terms of ionic permeability and selectivity are extremely high. Unfortunately, the transfer of these properties to artificial set-up whose the mechanical strength is high enough to be useful in many different types of applications has not been made, or even proposed, yet. Here, we report the first time extremely encouraging results obtained on a hybrid membrane made of a track-etched polycarbonate thin (thickness=5µm) film whose the nanopores (diameter=15nm) are filled with the ion channel Gramicidin-A (GA). The confinement of GA is checked by means of confocal fluorescence spectroscopy and the effective ion diffusion determined by means of ion diffusion coefficient measurement of various electrolytes, viz. 10-1, 10-2 and 5 10-3 mol.l-1 Na+, K+,Ca2+ and Mg2+ chlorine solution. Comparison with the effective ion diffusion coefficient measured on GA free membranes emphasizes that, when GA is absorbed into the nanopore, the effective ion diffusion significantly increases. Finally, simulations at the atomic level are conducted to confirm the GA insertion into a modeled hydrophobic nanopore, i.e. a carbon nanotube, and to gain some insights into the GA conformations in the pore.