Overview of Nanoscience in the Environment - Environmental and Human Health Impacts of Nanotechnology - page 9

system senses the presence of the contaminant in the surrounding environment. As
an example, ZnO semiconductor nanoclusters have been used to detect and destroy
aromatic compounds present in water with UV irradiation (Kamat et al. , 2002 ). A
variety of sensors for environmental applications have been developed in recent
years, including SnO 2 semiconductor systems that have been used as conductomet-
ric gas sensors (Barsan et al. , 1999 ; Sberveglieri, 1995 ), a TiO 2 electrode for deter-
mining the chemical oxygen demand (COD) of water (Kim et al. , 2001 ) and porous
silicon nanocrystals for detecting nerve gas agents (Sohn et al. , 2000 ) and nitrogen
containing organic compounds (Germanenko et al. , 2001 ).
Nanotechnology may also help the environment by addressing the long term
sustainability of resources (water, energy, materials, ecosystems, land and air) by
increasing materials and energy effi ciency, reducing the need for solvents and
reducing waste product volumes and concentrations (Rickerby and Morrison,
2007). Nanotechnology may reduce energy demand through more effi cient and
effective use of materials; the use lighter materials for vehicles, materials and geo-
metries for more effective temperature control, materials of better electrical trans-
mission and less dissipation and materials for the next generation of fuel cells. For
instance, cerium oxide nanoparticles have been used to decrease diesel emission
(Jung et al. , 2005). Quantum dots, nanoparticles of semiconductors, could make
more effi cient solar cells (Nozik, 2002). Nanoparticles in paint technology offer the
possibility of thinner, and therefore lighter, coatings, which could reduce, for
example, the weight of aircraft, increase fuel effi ciency and so reduce carbon dioxide
emissions. Advanced fi ltration may enable more water recycling and desalination,
which enable more energy - effi cient water purifi cation (Miyaki et al. , 2000 ).

1.7.2 Human Health

Nanotechnology has the potential to improve the lives of people in general and
especially of those with severe injuries or medical conditions. The following applica-
tions are either in the early stages of development (start of list) or discussed as
future possibilities (later in the list) (Bogunia-Kubik and Sugisaka, 2002; Roco and
Bainbridge, 2003 ; Roco, 2003 ; Zajtchuk, 1999 ):

• Provision of new formulations and routes for drug delivery to diffi cult organs
such as the brain, enormously broadening the drugs' therapeutic potential (Yih
and Al-Fandi, 2006). For example poly(butyl cyanoacrylate) nanoparticles coated
with polysorbate 80 can be used to enhance the delivery of apolipoproteins to
the brain (Kreuter, 2001). Ultrafi ne particles can mediate the delivery of [3H]-
dalargin to the brain (Alyaudtin et al. , 2001 ),
• Development of new vaccines (Cui and Mumper, 2003 ).
• Replacement of diseased organs and repair of nerve damage (Yang et al. , 2004a ).
• Early diagnoses, treatment and prevention of cancer and other diseases (Cuenca
et al. , 2006 ).
• Artifi cial nanoscale devices can be introduced into cells to play roles in diagnos-
tics and potentially as active components (Cornell et al. , 1997 ; Freitas, 1998 ).
• Mobilisation of the body 's own healing abilities to repair or regenerate damaged
cells and re-grow rapidly damaged neurons (Yang et al. , 2004a ).