Nanovalve, a soft membrane with variable diameter nanopores
< 10/16/2009 - by DRIP >
Context
Some drugs require a quasi-continuous delivery (insulin as an example). Hydrophobic PVDF membranes treated with poly (acrylic acid) are considered as a media of choice for drug administration. It has been reported that release of drugs through membranes could be controlled by the environmental pH. There is an interest in regulating the transmission through the nanopores by adjusting a voltage parameter.
Control of nanofluidics and hydrophilic/hydrophobic phase:
Poly (acrylic acid) undergoes a hydrophilic to hydrophobic (hydro-gel) phase transition depending on the solution pH. If the poly (acrylic acid) is confined to the interior of nanopores then the pH of the solution can effectively open or close the nanopores.
The technology and its advantages
Nanoporous membranes were prepared by the grafting of poly (acrylic acid) on etched latent tracks, mastering specific surface- or through pore grafting.
We can control the effective diameter of the nanopores from an open configuration to a losed configuration using a special arrangement of surface electrodes that can change the pH in the vicinity (1-10 microns) of the nanopores and thus change the nanopore diameter (see figure).
Advantages:
Not limited to pure charged species control or the need to change the solution pH by the external addition of chemicals thus allowing in situ operation.
Status
Technology under development, for more infos, see:
M.-C. Clochard, J. Bègue, A. Lafon, D. Caldemaison, C. Bittencourt, J.-J.Pireaux, N. Betz «Tailoring bulk and surface grafting of poly(acrylic acid) in electron-irradiated PVDF» polymer 45 (2004) 8683-8694.
O. Cuscito, M.-C. Clochard, S. Esnouf, N. Betz, D. Lairez «Nanoporous β-PVDF with selectively functionalized pores» Nuclear Instruments and Methods in Physics Research B 265 (2007) 309-313.
Intelectual Property
European Patent Application filled on March, 20 2009 under number EP09305252, “Nanovalve device comprising nanoporous membrane”.
