A Fundamental Review of the Relationships between Nanotechnology and Lignocellulosic Biomass - The Nanoscience and Technology of Renewable Biomaterials - page 9

address some major issues facing many nations, including energy security, global climate
change, air and water quality, and global industrial competitiveness. Other potential uses
for nanotechnology include developing intelligent wood- and paper-based products with
an array of nanosensors built in to measure forces, loads, moisture levels, temperature,
pressure, chemical emissions, detect attack by wood decay fungi, etc. Building function-
ality onto lignocellulosic surfaces at the nanoscale could open new opportunities for such
things as pharmaceutical products, self-sterilizing surfaces, and electronic lignocellulosic
devices (Atalla et al . 2005). Use of lignocellulosic biomass nanodimensional building
blocks will enable the assembly of functional materials and substrates with substantially
higher strength properties, which will allow the production of lighter-weight products
from less material and with less energy requirements. Nano-biomaterials could replace
a wide range of materials such as metals and petroleum-based plastics in the fabrica-
tion of products. Significant improvements in surface properties and functionality will
be possible, making existing products much more effective and allowing the develop-
ment of many more new products. Nanotechnology can be used to improve processing
of wood-based materials into a myriad of products by improving water removal and
eliminating rewetting; reducing energy usage in drying; and tagging fibers, flakes, and
particles to allow customized property enhancement in processing. The exact economic
impacts and opportunities for wood as a nanomaterial are unknown, but it is expected
that nanomaterials and nano-enabled products will grow to exceed US$1 trillion per year
as the technology is further developed and is widely applied commercially during the
21st century (National Research Council 2006).
Nanotechnology can also play an important role in the production of liquid biofuels
from lignocellulosic biomass. For example, nanoscale cell walls structures within trees
could be manipulated so they are more easily disassembled into constitutive materials
for liquid fuels production whether through conversion by fermentation, gasification, or
catalysis. Another approach would be to use nanocatalysis to break down recalcitrant
cellulose. Recalcitrant cellulose is in the order of 15-25% of the carbohydrate frac-
tion of wood and failure to convert this to sugars reduces fermentation ethanol yields.
In this approach, nanocatalysts would need to be transported to the reaction sites on
the solid substrate recalcitrant cellulose in order to produce water soluble polyol reac-
tion products. In most catalysis schemes, the reactants are brought to the catalyst.
In this case the catalyst needs to be brought to the solid substrate reaction sites and
water soluble reaction products need to be generated in order to permit recovery of the
catalysts. Other possibilities for nanotechnology approaches in biofuel production are
through development of engineered nanoscale enzymes or systems of enzymes (including
glycol hydrolases, expansins, and lignin degrading enzymes) for improved conversion
efficiency. Tree biology could be engineered so that enzymes and enzyme systems are
created and stored/sequestered in the living tree until harvest and then be activated for
engineered woody biomass self-disassembly. Lastly, another concept would be to create
new symbiotic nanoscale biological systems which work together to create ethanol or
other biofuels.
Cellulose, while at times referred to as a nanofibril, does not differ much from a
coiled nanoribbon. Nanoribbons have been developed specifically as optical wave-
guides for channeling optical and visible light. Nanodimensional cellulose has already
been used as a template to form nanoribbons of Antimony (III) oxide that can then be