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Nanotechnology has found applications in almost all the industries
including, ICT,
aerospace, automotive, energy, security and healthcare. Perhaps
medicine and healthcare may be one of the sectors that have benefitted most from
this novel science.
Nanomedicine has grown as a discipline by itself and the development of
novel
structures and advances in nanomaterials are fuelling the growth and
innovation in the area. The potential of nanotechnology in medicine has been recognised
by policy makers in the same way as scientists. Significant amount of funding has
been provided into the sector. The number of conferences taking place around the
globe on nanotech applications in medicine is an indicator of the interest and hope
offered by nanoscience and
nanotechnology. The Cancer Nanotechnology plan by the National
Cancer Institute in US and the Nanomedicine Technology Platform in the Europe has set
out plans for
the future research activities needed in the area. In addition to that
a roadmap project which sets out the timeframe for nanomedicine applications have been
supported by the European Commission (EC). Several other projects related to
nanomedicine have been funded by the EC in the 6th Frame Work programme. There also exist many
national and pan-European networks which aim to bring together stakeholders from
different avenues to discuss and share information. Nanomednet in UK, Nanoned in
Netherlands, Spanish nanomedicine platform, CC-NanoBioTech in Germany, CLINAM etc.
are
examples of such networks which aim to bridge the gap between different
groups which include scientists, industry, clinicians, investors and policy makers.
Short courses and summer schools offered by the Nanomednet and European Science
Foundation are extremely useful for clinicians as well as researchers. The following
review aimed to look into the nanomedicine landscape to understand the new developments
in the area and reports some of the novel innovations which can change the way we
treat ourselves.
The study divided the nanomedicine sector into five different
sub-sectors and looked at
the scientific breakthroughs and advances in each of them. The sectors
are:
Therapeutics, Diagnostics, Regenerative Medicine, Implants, Surgery and
Coatings and Novel Bionanostructures. In addition to that a sixth sub-sector,
Cosmetics has also been examined under nanomedicine as some of the nanotechnologies used in the
cosmetics industry have already been reported as potential candidates for drug
delivery. In each of the sub-sector reviews, the key technologies and their descriptions are
provided. State of the R&D in that particular area is described and additional
demands for research required for each of the sub-sectors are briefly outlines. However,
expert input is required to fill the gaps in both the technology review and research
requirements.
Need for creating novel nanostructures for the targeted and localised
delivery of drugs has driven innovations in the drug delivery sector. The market for
nanotechnology enabled drug delivery is expected to grow to US $20.1 billion by 2012
capturing an 11% share of the global drug delivery market. In 2008, the
nanotechnology-enabled
drug delivery market is estimated at US $4.1 billion, or 4% of the global
drug delivery market.
This enormous growth will be due to the development of new systems
which improve the solubility and bioavailability of drugs and the design of new
mechanisms that can target drugs to specific cells or tissues. In addition to that attempts are
being made to improve the circulatory presence of drugs to enhance the cellular uptake and
drug efficiency.
Polymers, particularly Poly Ethylene Glycol (PEG) have been widely used
to functionalise nanoparticles and other nanostructures. In addition to
improving the solubility and stability of the conjugates, PEG reduces protein
immunogenicity and prevents the rapid renal clearance of drug molecules. Nanoparticles,
nanotubes as well as nanohorns have been tried as potential drug carriers. Out of this,
nanoparticles have been widely considered as the most suitable materials to deliver drugs.
Colloidal gold nanoparticles, magnetic nanoparticles and ceramic nanoparticles have
been
successfully tested for its efficacy in drug delivery applications.
Some of these particles have also been used simultaneously for imaging and drug delivery
opening up new possibilities in therapeutics. This has opened up a new branch of study
in medicine
called, Theranostics. Proteins like albumin have been modified to form
nanoparticles and are used in delivering drugs. The albumin based technology for
delivering the cancer
drug paclitaxel have been commercialised into the market by Abraxis
Biosciences Inc.
Similarly Magforce Nanotechnologies are using magnetic nanoparticles
for the treatment
of various carcinomas including brain tumour. Nanocrystallisation
technology developed by Elan Corporation is used by many big pharmaceutical companies like
Wyeth, Abbot and Merck to improve the solubility of their drugs. Lipid Nanoparticles,
nanoemulsions and nanosuspensions have also been utilised for drug delivery. One of
the first developed nanostructure, liposomes is being modified for improving its
drug loading efficiency. Micelles and Dendrimers are other two different types of
nanostructures which
show huge potential. Starpharma is developing gels using dendrimers to
prevent the transmission of deadly virus HIV. Carbon nanotubes due to their
increased surface area and high drug loading capability have also been considered as drug
carriers.
Advances in novel fabrication techniques, development of new materials
and surface
modification methods are driving innovations in diagnostics. The
ability to create sensors which can detect analytes in the nano and femto molar ranges is of
extreme importance in the early detection of diseases and discovery of new drugs. Along
with carbon nanotubes and carbon nanofibres, nanowires have also been modified to
create sensors. Changes in conductance of nanowires due to the binding of
target molecules are monitored to find the subject of interest. Nanoshells and magnetic
nanoparticles
have also been used to create nanosensors. Tiny sensors which can
detect virus nanoparticles from microlitre volumes have been developed.
Nanotechnology has also been used in developing optical biosensors, genomic sensors,
immunosensors and enzymatic sensors. Metallic barcodes (nanobarcodes) prepared by the
electrochemical deposition of sub micron level particles in a striped format have been
used in multiple bioassays. Cantilevers have also been used to create nanobiosensors.
One of the advantages of cantilevers is that scale up is an easy process compared
to others.
Different types of nanoparticles are used for molecular imaging. Silica
nanoparticles,
gold nanoparticles and magnetic nanoparticles are widely used. However,
quantum dots are proposed as the best material for imaging purposes.
Surface-enhanced resonance raman scattering (SERRS) and the underlying principles have been
utilised for imaging and diagnostics. Attempts are being made to incorporate nanosensors in
handheld devices and to make them compatible with silicon technology for easy
integration.
Advances in lab-on-a-chip technologies and microfluidics are driving
the integration
processes. Laboratory-in-a-cell (LIC), the concept of putting a single
cell on a chip and using nanotechnological tools to understand the complex biochemical
operations is slowly getting momentum. Nanobioreactors and Cell-on-a-chip devices
have also been developed using novel fabrication methods. Nanotechnology is also
enabling the control of liquids through nanofluidic channels. Nanopore, a small pore of
nanoscale dimension in a solid state membrane or a protein channel have been used to create
sensors and incorporated in handheld devices. High resolution 3D light microscope
with resolutions
in the range of 40 nm has been developed. Carbon nanotubes have also
been proposed as scanning probe tips to improve the resolution of images.
Progresses in novel characterisation tools are enabling researchers to
manipulate the surface characteristics of materials to enhance their cellular growth
properties. The ability to create extracellular matrices (ECM) using nanostructured
materials have been successfully utilised to improve the cell growth, adhesion, migration,
and differentiation.
Conjugating nanomaterials with polymers to create
nanocomposite
scaffolds have been
used for bone and cartilage regeneration. Nanophase materials of size
less than 100 nm have been successfully used for bone and dental implants. One of the
major advantages of nanotechnology is that it can improve the biocompatibility of the
implants either by coating the implants with nanomaterials or by the use of nanomaterials
as implant
materials. Synthetic nanofibres and natural nanofibres have been
processed to create scaffolds to grow different cell lines. Bioactive molecules have been
incorporated into the
scaffolds to trigger molecular functions in a timely fashion. Magnetic
nanoparticles have
been used to control the development of multilayered cell sheet-like
structures, ECM and tubular structures. Cell sheet engineering using temperature sensitive
polymers have also been proposed to regenerate cells. Nanotechnology has been
utilised to improve bone and dental implants, cartilage implants, esophageal, tracheal and
bladder Implants and vascular implants. The technology is also enhancing prospects in
surgery with the development of nanoneedles which can penetrate cells without damaging
them and nanotweezers that can move single biological molecules within cells.
Methods to
improve the sharpness of surgical blades using nanostructured carbon
coatings have been developed. Femtosecond lasers for precision cutting have potential
applications in eye surgery. Carbon nanotubes have been proposed to create catheters
and silver nanoparticles have been coated onto them to improve the antibacterial
properties.
Nanosilver has also been added onto wound care dressings as well as
fabrics. Selfassembling peptides that can create a nanofibre mesh to stop bleedings have also
been created. New materials to create stents as well as coatings to promote
endothelial growth have been developed. The coatings are also used to incorporate
drugs for controlled delivery. Carbon nanofibres and nanotubes are considered as
suitable materials for use in neural implants. Batteries suitable for
implantable devices like
pacemakers which can convert body heat into electricity have been
developed.
Nanotechnology has also been applied to crate synthetic cells which can
mimic the
natural cell structure and carry out normal cells operations including
self replication. The availability of novel tools which can fabricate cells using different
synthetic materials has been proposed. Membranes that can communicate to each other have also
been developed using this approach. Several other structures like liposomes,
nanoemulsions and polymers have been used to create synthetic cells. DNA nanocages
formed by the self assembly of DNAs have been utilised for drug and nanoparticle
encapsulation. The
self assembling properties of molecules have been used to create
molecular switches and molecular motors. Catenanes and Rotaxanes have been used to create
molecular machines. Similarly, DNA has been manipulated to create DNA switches
and nanomotors which use energy from ATP hydrolysis as natural motors.
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