This book addresses the possibilities and challenges in mimicking
biological membranes and creating membrane-based sensor and separation
devices. Recent advances in developing biomimetic membranes for
technological applications will be presented with focus on the use of
integral membrane protein mediated transport for sensing and separation.
It describes the fundamentals of biosensing as well as separation and
shows how the two processes are working in a cooperative manner in
biological systems. Biomimetics is a truly cross-disciplinary approach
and this is exemplified using the process of forward osmosis will be
presented as an illustration of how advances in membrane technology may
be directly stimulated by an increased understanding of biological
membrane transport. In the development of a biomimetic sensor/separation
technology, both channels (ion and water channels) and carriers
(transporters) are important. An ideal sensor/separation device requires
the supporting biomimetic matrix to be virtually impermeable to anything
but the solute in question. In practice, however, a biomimetic support
matrix will generally have finite permeabilities to water, electrolytes,
and non-electrolytes. These non-protein mediated membrane transport
contributions will be presented and the implications for biomimetic
device construction will be discussed. New developments in our
understanding of the reciprocal coupling between the material properties
of the biomimetic matrix and the embedded proteins will be presented and
strategies for inducing biomimetic matrix stability will be discussed.
Once reconstituted in its final host biomimetic matrix the protein
stability also needs to be maintained and controlled. Beta-barrel
proteins exemplified by the E. Coli outer membrane channels or small
peptides are inherently more stable than alpha-helical bundle proteins
which may require additional stabilizing modifications. The challenges
associated with insertion and stabilization of alpha-helical bundle
proteins including many carriers and ligand and voltage gated ion (and
water) channels will be discussed and exemplified using the aquaporin
protein. Many biomimetic membrane applications require that the final
device can be used in the macroscopic realm. Thus a biomimetic
separation device must have the ability to process hundred of liters of
permeate in hours - effectively demanding square-meter size membranes.
Scalability is a general issue for all nano-inspired technology
developments and will be addressed here in the context biomimetic
membrane array fabrication. Finally a robust working biomimetic device
based on membrane transport must be encapsulated and protected yet
allowing massive transport though the encapsulation material. This
challenge will be discussed using microfluidic design strategies as
examples of how to use microfluidic systems to create and encapsulate
biomimetic membranes. The book provides an overview of what is known in
the field, where additional research is needed, and where the field is
heading.
