In materials
science, nanocomposites with nanoscale dispersed phases and nanocrystalline
materials in which the very fine grain size affords quite different mechanical
properties to conventional microstructures are already in use. In surface
science and surface engineering, nanotopographies offer substantially different
properties related to adhesion, tribology, optics and electronic behaviour.
Supramolecular chemistry and catalysis have led to novel surface and size
dependent chemistry, such as enantioselective catalysis at surfaces. In
biological sciences, fundamental understanding of molecular motors and
molecular functional entities on the nanometre scale has been responsible for
advances in drug design and targeting. Nanoscale functionalised entities and
devices are in development for analytical and instrumental applications in
biology and medicine, including tissue engineering and imaging. The application
areas in which these advances in nanoscience are making their biggest impact
include electronic, electro-optic and optical devices. The transition from
semiconductor (conventional and organic) technology to nanoscale devices has
anticipated improved properties and resolution, e.g. fluorescence labelling,
scanning probe microscopy and confocal microscopy. Data storage devices based
on nanostructures provide smaller, faster, and lower consumption systems. In medicine,
greater understanding of the origin of diseases on the nanometre scale is being
derived, and drug delivery through functionalised nanostructures may result in
improved pharmacokinetic and targeting properties. A wide variety of
functional nanoscale materials and functional nanoscale surfaces are in use in
consumer products, including cosmetics and sunscreens, fibres and textiles,
dyes, fillers, paints, emulsions and colloids.Source & ©: SCENIHR
The appropriateness of existing methodologies to assess the potential
risks associated with engineered and adventitious products of nanotechnologies
(2006),3.3 Nanoscience and Nanotechnology, p. 11 3.3.4 Nanoscale
materials properties Material
properties depend on structure and composition, and can typically be engineered
or modified by changing the relative influence of interfacial or interphase
properties and the macroscopic bulk properties through the characteristic size
or dimension of components and domains. This approach had already emerged
centuries ago with steel alloys and has been so powerful that many engineering
materials today are composites with micro to nanoscale domain sizes. Depending
on the physical or chemical character of each domain, there is a complex
interrelation between the structure and the composition of the material, which
may relate to the bulk and surface properties of each ingredient and newly
emerging properties localized at the interface. selective chemical reactivity
is quite common with nanocomposites, which gives the potential for
disintegration of the material into one or the other component. Complex
processes govern this behaviour, which clearly relates to nanoparticle release
into the environment. 3.3.5 Conclusions. The exploitation
of the properties associated with the nanoscale is based on a small number of
discrete differences between features of the nanoscale and those of more
conventional sizes, namely the markedly increased surface area of nanoparticles
compared to larger particles of the same volume or mass, and also quantum
effects. Questions naturally arise as to whether these features pose any
inherent threats to humans and the environment. Bearing in mind that naturally
occurring processes, such as volcanoes and fires, in the environment have been
generating nanoparticles and other nanostructures for a very long time, it
would appear that there is no intrinsic risk associated with the nanoscale per
se for the population as a whole. As noted above, there is also no reason to
believe that processes of self assembly, which are scientifically very
important for the generation of nanoscale structures, could lead to
uncontrolled self perpetuation. The real issues facing the assessment of risks
associated with the nanoscale are largely concerned with the increased exposure
levels, of both humans and environmental species, now that engineered
nanostructures are being manufactured and generated in larger and larger
amounts, in the new materials that are being so generated, and the potentially
new routes by which exposure may occur with the current and anticipated
applications. |