Nanofabrication MEMS

While engineers and scientists race to shrink the size of
transistors and MEMS components through nanofabrication
to create the next generation of high-performance electronic
devices, biologists and life scientists have just begun to
employ micropatterning and, to a more limited extent,
nanopatterning techniques to build high-throughput
detection systems for genomic and proteomic studies

Opportunities and challenges
The incorporation of ‘soft-wet’ biological components into
conventional nanofabrication platforms designed and built for
‘hard-dry’ semiconductors, conductors, and dielectrics brings
both new opportunities and challenges since biomolecules
possess some unique properties:
• A wide range of biomolecules, including nucleic acids,
proteins, lipids, and oligosaccharides, react with other
biological components by molecular recognition14,15,
which is important for bottom-up nanofabrication based
on self-assembly;
• Enzymes can catalyze the synthesis and removal of both
biological and synthetic molecules16,17;
• Biomolecular reactions (biotransformations) are highly
selective and site-specific17. There are many enzymes that
cleave DNA at particular sites (restriction enzymes) and
link two pieces of DNA together (ligases)17. Proteases that
digest proteins at specific sites16,17 and enzymes that add
functional motifs to proteins18 are just a few examples of
protein-modifying enzymes;
• Biomolecular reactions are often highly efficient under
physiological conditions, so the yields of
biotransformations are substantially higher than those by
chemical syntheses19,20; and
• The use of biomolecules and biological processes is often
environmentally friendly, so treatment of the waste
products can be minimal and the by-products pose little
health risk compared to the reagents used in
semiconductor processing.
On the other hand, there are also significant constraints
associated with the use of biomolecules in
bionanofabrication. These are:
• The ultrahigh-vacuum (UHV) conditions used in
conventional nanofabrication approaches are incompatible
with biomolecules, whose function and structural integrity
in most cases are destroyed in a high-vacuum
environment;
• Even in an aqueous environment, many proteins can easily
lose their native, active conformation after deposition
because they can unfold and bind nonspecifically to a
surface; and Biological reactions, with some notable exceptions21,22,
must take place in an aqueous solution or buffer, which
limits their uses in many electronic applications.

Chow D C et al, Nanofabrication with Biomolecules, NanoToday, Elsevier, Dec 2005

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