Flexible Membranes Mimic Gastric Acid Secretion of Human Body in Active Transport of Hydrochloric Acid-Research May Lead to Nanostructures for Fuel Cells, Filtration and Smart Fabrics

Professor John Cuppoletti, University of Cincinnati, Department of Molecular and Cellular Physiology  is leading a research team developing membranes for fuel cells, filtration, drug delivery and smart fabrics for the U.S. Army. 

The objective of this U.S. Army Research Office Multi-disciplinary University Research Initiative (MURI) is to produce synthetic flexible membranes containing biological transport proteins that can utilize energy for the selective uptake, concentration and release of ions and molecules in an organized manner. The effort includes production of both macroscopic membranes and nanostructures containing transport proteins with vectorial transport function.  The investigation is noted in 2009 ARO  in Review, a publication noting on-going U.S. Army materials and other research.

The University of Cincinnati research combines both experimental and theoretical studies utilizing a very promising membrane transport system; the fundamental concepts developed from this effort are expected to provide significant insight into many other transport systems. The MURI program may enable novel materials for: fuel cell membranes, reverse osmosis and active filter membranes, drug delivery systems, moisture-removing fabrics, and chemical and biological defense. The research program includes:

• Reconstitution of the gastric HCl secretory apparatus into synthetic flexible membranes in functional form;

• Investigation of the structural determinants of regulatory regions in native and specifically modified or engineered proteins;

• Application of control mechanisms such as pH, ionic conditions, membrane voltage, and intracellular second messengers;

• Identification and engineering, using guidance from computational modeling, of transport systems with the capability to transport other substances; and

• Design of macroscopic and nanoscopic planar and three-dimensional membrane support structures.

Catalog of Nanofilms for Filtration Unveiled

One field that will benefit from nanotechnology is filtration using membranes.
Covalent Partners, LLC (Hayward, CA) inventors Joshua W. Kriesel, Donald B. Bivin, David J. Olson and Jeremy J. Harris developed a catalog of nanofilms with polymeric components that can be made impermeable to viruses and larger biological species. The films are used to make selectively permeable membrane barriers for the separation or filtration of materials from fluids, according to United States Patent 7,595,368. The 134 page patent divulges a variety of nanofilms for material separation.

Conventional membranes used in a variety of separation processes can be made selectively permeable to various molecular species. The permeation properties of conventional membranes generally depend on the pathways of transport of species through the membrane structure. For example, while the diffusion pathway in conventional selectively permeable materials can be made tortuous in order to control permeation, porosity is not well defined or controlled by conventional methods. The ability to fabricate regular or unique pore structures of membranes is a long-standing goal of separation technology. Covalent’s discoveries are a step closer to that goal.

Selective filtration and relative clearance of solutes is exemplified in the Table Clearance of Solutes by Nanofilms, where the heading "high permeability" indicates a clearance of greater than about 70-90% of the solute. The heading "medium permeability" indicates a clearance of less than about 50-70% of the solute. The heading "low permeability" indicates a clearance of less than about 10-30% of the solute.



Nanoflims for filtration were prepared from amphiphilic species and one or more polymeric components. The amphiphilic species or components may be oriented on an interface or surface. Nanofilms may be prepared by coupling one or more of the components. The nanofilms may also be deposited or attached to a substrates.