If we define nanotechnology as the application of materials and devices with
characteristic (i.e. property determining) length scales between 1 and 100nm to
the development of new products and processes; then bionanotechnology is its
interface with biological systems.
Biology too has many examples of materials and structures that share a common
length scale with nanotechnology, however it is the requirement for application
that distinguishes bionanotechnology from biophysics or structural biology or
virology. This is the same distinction that separates biotechnology from
molecular and cell biology or physics from electronics and chemical engineering
Recognising that nanotechnology and biology share common length scales at
this level we can see how the combination of the two creates the opportunity to
produce and apply novel hybrid structures, materials and devices that exploit
the distinctive features of both. Exploitation spans the use of nanomaterials as
tools in fundamental biological research, the development of novel approaches to
diagnose and treat disease as well as new ways to generate energy or clean up
the environment. The link between biology and nanotechnology is also seen in
processes common to both domains such as self-assembly of the importance of
kinetic rather than thermodynamic control in creating and maintaining
structures. There are also significant differences between the two realms,
perhaps most significantly the observation that many biological structures have
only marginal stability at ambient temperatures with respect to non-functional
states. This can have important implications for building hybrid bionano
constructs and it is in the design and fabrication of such "hard-soft"
interfaces that bionanotechnology's distinctive flavour lies.
In bionanosensors we can see how biomolecules and nanomaterials can be
combined to mutual advantage and produce devices with applications in clinical,
environmental and bioprocess monitoring. The enhancement of bionanosensors
compared to conventional biosensors arises from the fact that many nanomaterials
have optical, electronic or magnetic properties that were unanticipated from
knowledge of the bulk (macroscopic) material, largely as a consequence of the
greater proportion of atoms in the former being at or near the surface.
Fabrication of particles, wires, pores, films or more complex structures with
enhanced optical, electronic, magnetic or mechanical characteristics produce a
new family of base sensors that lack only the molecular specificity necessary to
use them in complex backgrounds. Of course it is such molecular recognition
specificity that is the hallmark of biomolecules and the interface between the
two is what provides bionanosensors with their analytical power.
As with conventional biosensors however, the native biomolecular properties
are not always sufficient to provide an effective sensing interface as they have
evolved to fit a specific biological role, not a sensing one. If anything the
situation is even more acute with bionanosensors as the high surface sensitivity
of nanomaterials is best exploited when the biomolecule retains a high level of
function. Molecular engineering can address this issue as well as others such as
adjusting the dynamic range or enhancing stability.
In conclusion we can see therefore that bionanosensors put engineering at all
length scales, from the molecular to the everyday at the heart of applying
bionanotechnology in analytical science.
Copyright AZoNano.com, Professor Tony Cass (Imperial College
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