nano tech in medicine by lakshmidhar


									                 NANOTECHNOLOGY IN MEDICINE
             T.SUJANA                                    T.VINOD
                  ¾ CSE                                          ¼ MEC

                  KOMMADI                                 MADHURAWADA
                  VISAKHAPATNAM                           VISAKHAPATNAM

                              With in few decades, and perhaps sooner Nanotechnology is
emerging as enabling technology that is expected to redesign the future of several
technologies and products and is expected to replace many existing technologies in use today.
                          This technology is to change major aspects of our lives and to lead
for generation of new capabilities, new products and ultimately new markets. One major
aspect associated with Nanotechnology is that it is multi-disciplinary technologies with wide
spectrum    of    applications – Nanomaterials, Nano-electronics, Nano-biotechnology,
Nanomedicine and Nanosurgery etc. as broad classification. If this possible, the policy
implications are enormous.
                             Nanotechnology is manufacturing at molecular level of building
things from nano-scale components. The word Nano comes from Greek word,”Nanos”
meaning dwarf. Nano is factor of one-billionth.

                 “Thinking small to think big” is a Best caption for
              Norio Taniguchi at the University of Tokyo coined the word nano technology.
Later during 1950's Arthur Von Hipper, an electrical engineer from the Massachusetts
Institute of Technology coined the term 'molecular engineering' and predicted the feasibility
of constructing the monomolecular devices. In 1959 the Nobel Laureate physicist Richard Fey
Mann was he first to present the concept of nanotechnology to the world and Suggested that
the manipulation of individual atoms could revolutionize science. Later in 1979 two IBM
researchers invented the scanning Tunneling Microscope. Eric Drexel, chairman of the
Foresight Institute in the mid 1970's came to a conclusion in his book "Engines of Creation",
the term "nano" is a specialized subset of Nanotechnology or MNT (Molecular
Nanotechnology) as it is now called.

                                     As is the awareness with us, Diseases and ill-health are
caused by damage at the molecular and cellular level, which gradually multiplies affecting the
system as a whole. The medicine/drug consumed to cure a particular ailment has to survive a
long journey through the stomach and reach the intestine intact and then come into circulation
crossing the intestinal wall. Once in blood, it gets filtered through the liver and travels through
the body resisting acids of digestive juices, jump membrane barriers and then act on specified
area of damage in the system. The challenges in the existing medicinal systems are for
protein-based pharmaceuticals which are broken down when taken orally, killer diseases are
growing more resistive to drugs, surgical tools are large and crude much suited to tear and
injure rather than heal and cure.
                                Molecular Nanotechnology has emerged as three-dimensional
positional control of molecular structure to create materials and devices to molecular
precision. The human body is comprised of molecules hence the availability of molecular
Nanotechnology is progressing dramatically to support human medical services.
Nanomedicine will use molecular knowledge to maintain and improve human health
using/employing molecular machine system to address medical problems.
                                       Nanotechnology has led to a major development in the area
of health and medicine. This could happen because of integration of biotechnology and
Nanotechnology. This confluence led to the exciting developments of Nano-devices having
bio-capabilities. For e.g. Nanorobots for medical diagnostics, genetic testing, new kinds of
drug-delivery systems to pervade the blood stream target contaminated cells, artificial
replacement and placebos at the nanoscales. The supportive developments are a group of
devices called MEMS (Micro Electro Mechanical Systems) devices that consist of tiny
elements manufactured using lithographic techniques to achieve micro-dimensions that
function like traditional larger devices.
                                    The integration of biotechnology, nanotechnology and
information technology has a very large impact on MEMS and the efforts are now towards
tinier MEMS and these devices are now known as NEMS (Nano Electro Mechanical Systems)
and find applications in medicine, hospital, gathering information about body conditions,
medicine transportation in the body, rapid deployment of environment friendly technology to
reduce environmental degradation.

                                "It is the roundest and most symmetrical large molecule
known to man. Buckministerfullerine continues to astonish with one amazing property after
another. Named after American architect R. Buck minister Fuller, who designed a geodesic
dome with the same fundamental symmetry, C60 is the third major form of pure carbon;
graphite and diamond are the other two. AKA: C60 molecules & Buckministerfullerine.
Molecules made up of 60 carbon atoms arranged in a series of interlocking hexagons and
pentagons, forming a structure that looks similar to a soccer ball C60 is actually a "truncated
icosahedrons", consisting of 12 pentagons and 20 hexagons. It was discovered in 1985 by
Professor Sir Harry kroto, and two Rice University professors, chemists Dr. Richard E.
Smalley and Dr. Robert F. Curl Jr., and The only molecule composed of a single element to

form a hollow spheroid

                      "The buckyball, being the roundest of round molecules, is also quite
resistant to high speed collisions. In fact, the buck ball can withstand slamming into a
stainless steel plate at 15,000 mph, merely bouncing back, unharmed. When compressed to 70
percent of its original size, the buckyball becomes more than twice as hard as its cousin,


                A one-dimensional fullerene (a convex cage of atoms with only hexagonal
and/or pentagonal faces) with a cylindrical shape. Carbon nanotubes discovered in 1991 by
Sumio Iijima resemble rolled up graphite, although they cannot really be made that way.
Depending on the direction that the tubes appear to have been rolled (quantified by the 'chiral
vector'), they are known to act as conductors or semiconductors. Nanotubes are a proving to
be useful as molecular components for nanotechnology. Strictly speaking, any tube with
nanoscale dimensions, but generally used to refer to carbon nanotubes, which are sheets of
graphite rolled up to make a tube. A commonly mentioned non-carbon variety is made of
boron nitride, another is silicon. These no carbon nanotubes are most often referred to as
nanowires. The dimensions are variable (down to 0.4 nm in diameter) and you can also get
nanotubes within nanotubes, leading to a distinction between multi-walled and single-walled
nanotubes. Apart from remarkable tensile strength, nanotubes exhibit varying electrical
properties (depending on the way the graphite structure spirals around the tube, and other
factors, such as doping), and can be super conducting, insulating, semi conducting.

                        Nanotubes can be either electrically conductive or semi conductive,
depending on their helicity, leading to nanoscale wires and electrical components. These one-
dimensional fibers exhibit electrical conductivity as high as copper, thermal conductivity as
high as diamond, strength 100 times greater than steel at one sixth the weight, and high strain
to failure. NASA JSC - Carbon Nanotubes a nanotube's chiral angle--the angle between the
axis of its hexagonal pattern and the axis of the tube--determines whether the tube is metallic
or semi conducting. Nanotubes under Stress a graphene sheet can be rolled more than one
way, producing different types of carbon nanotubes. The three main types are armchair,
zigzag, and chiral.

                        Examples Carbon nanotubes possess many unique properties, which
make them ideal, AFM probes. Their high aspect ratio provides faithful imaging of deep
trenches, while good resolution is retained due to their nanometer-scale diameter. These
geometrical factors also lead to reduce tip-sample adhesion, which allows gentler imaging.
Nanotubes elastically buckle rather than break when deformed, which results in highly robust
probes. They are electrically conductive, which allows their use in STM and EFM (electric
force microscopy), and they can be modified at their ends with specific chemical or biological
groups for high-resolution functional imaging. Professor Charles M. Lieber Group CNT
exhibits extraordinary mechanical properties: the Young's modulus is over 1 Tera Pascal. It is
stiff as diamond. The estimated tensile strength is 200 Giga Pascal. These properties are ideal
for reinforced composites, nanoelectromechanical systems (NEMS).

                      Carbon Nanotube Transistors exploit the fact that nm- scale nanotubes
(NT) are ready-made molecular wires and can be rendered into a conducting, semi
conducting, or insulating state, which make them valuable for future nanocomputer design. ...
Carbon nanotubes are quite popular now for their prospective electrical, thermal, and even
selective-chemistry applications. Any potential application have been proposed for carbon
nanotubes, including conductive and high-strength composites; energy storage and energy
conversion devices; sensors; field emission displays and radiation sources; hydrogen storage
media; and nanometer-sized semiconductor devices, probes, and interconnects. One, hydrogen
storage, is clouded by controversy. Nanotube cost, polydispersity in nanotube type, and
limitations in processing and assembly methods are important barriers for some
nanotechnology applications
                    "Living organisms are naturally-existing, fabulously complex systems of
molecular nanotechnology." - Dr. Gregory Fahy .
                    The above statement raises the interesting possibility that machines
constructed at the molecular level (nanomachines) may be used to cure the human body of its
various ills. This application of nanotechnology to the field of medicine is commonly called
as nanomedicine.
(i) NANOROBOTS (Is It Possible?): -

                          Nanorobots are nanodevices that will be used for the purpose of
maintaining and protecting the human body against pathogens. They will have a diameter of
about 0.5 to 3 microns and will be constructed out of parts with dimensions in the range of 1
to 100 nanometers. The main element used will be carbon in the form of diamond / fullerene
nanocomposites because of the strength and chemical inertness of these forms. Many other
light elements such as oxygen and nitrogen can be used for special purposes. To avoid being
attacked by the host’s immune system, the best choice for the exterior coating is a passive
diamond coating. The smoother and more flawless the coating, the less the reaction from the
body’s immune system. Such devices have been designed in recent years but no working
model has been built so far.
                               A navigational network may be installed in the body, with
stationkeeping navigational elements providing high positional accuracy to all passing
Nanorobots that interrogate them, wanting to know their location. This will enable the
physician to keep track of the various devices in the body. These Nanorobots will be able to
distinguish between different cell types by checking their surface antigens (they are different
for each type of cell). This is accomplished by the use of chemotactic sensors keyed to the
specific antigens on the target cells.
                      When the task of the Nanorobots is completed, they can be retrieved by
allowing them to exfuse themselves via the usual human excretory channels. They can also be
removed by active scavenger systems. This feature is design-dependent.
Some possible applications using Nanorobots are as follows:
1. To cure skin diseases, a cream containing Nanorobots may be used. It could remove the
   right amount of dead skin, remove excess oils, add missing oils, apply the right amounts
   of natural moisturizing compounds, and even achieve the elusive goal of 'deep pore
   cleaning' by actually reaching down into pores and cleaning them out. The cream could be
   a smart material with smooth-on, peel-off convenience.
2. Medical nanodevices could augment the immune system by finding and disabling
   unwanted bacteria and viruses. When an invader is identified, it can be punctured, letting
   its contents spill out and ending its effectiveness. If the contents were known to be
   hazardous by themselves, then the immune machine could hold on to it long enough to
   dismantle it more completely
3. Devices working in the bloodstream could nibble away at arteriosclerotic deposits,
   widening the affected blood vessels. Cell herding devices could restore artery walls and
   artery linings to health, by ensuring that the right cells and supporting structures are in the
   right places. This would prevent most heart attacks.
4. A mouthwash full of smart nanomachines could identify and destroy pathogenic bacteria
   while allowing the harmless flora of the mouth to flourish in a healthy ecosystem. Further,
   the devices would identify particles of food, plaque, or tartar, and lift them from teeth to
   be rinsed away.
7.HOW LONG?: -
                    The abilities discussed here might well take years or decades to develop. It
is quite natural to ask: "When might we see these systems actually used?" The scientifically
correct answer is, of course, "We don't know." That said, it is worth noting that if progress in
computer hardware continues as the trend lines of the last 50 years suggest, we should have
some form of molecular manufacturing in the 2010 to 2020 time frame. After this, the medical
applications will require some additional time to develop.
                     The remarkably steady trend lines in computer hardware, however, give a
false sense that there is a "schedule" and that developments will spontaneously happen at their
appointed time. This is incorrect. How long it will take to develop these systems depends very
much on what we do. If focused efforts to develop molecular manufacturing and its medical
applications are pursued, we will have such systems well within our lifetimes. If we make no
special efforts the schedule will slip, possibly by a great deal.


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