NANOTECHNOLOGY - A NEW VISION ABSTRACT

Nanotechnology is one of the most exciting topics in modern world and has a dizzying array of applications in areas as diverse as clinical medicine, industrial catalysis, and consumer electronics. Nanotechnology uses nanostructures for its functioning. These have a very broad range of electronic, thermal and structural properties.

INTODUCTION

Nanotechnology (sometimes shortened to "nanotech") is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with developing materials, devices, or other structures possessing at least one dimension sized from 1 to 100 nanometres.

It seems that size limitations of nanotechnology to the 1-100nm range. The nano structure has special properties that are exclusively due to nanoscale propotions.

There is much debate on the future implications of nanotechnology. Nanotechnology may able to create many new materials and devices with a vast range of applications, such as in medicine, electronics, biomaterials and energy production.

Nanotechnology is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new materials with dimensions on the nanoscale to investigating whether we can directly control matter on the atomic scale

NANOSCALE

A nanometer (nm) is one thousand millionth of a meter. For comparison, a red blood cell is approximately 7,000 nm wide and a water molecule is almost 0.3nm across. . The bulk properties of any material are merely the average of all the quantum forces affecting all the atoms. As you make things smaller and smaller, you eventually reach a point where the averaging no longer works. The properties of materials can be different at the nanoscale for two main reasons: First, nanomaterials have a relatively larger surface area when compared to the same mass of material produced in a larger form. This can make materials more chemically reactive (in some cases materials that are inert in their larger form are reactive when produced in their nanoscale form), and affect their strength or electrical properties. Second, quantum effects can begin to dominate the behaviour of matter at the nanoscale - particularly at the lower end - affecting the optical, electrical and magnetic behaviour of materials. Materials can be produced that are nanoscale in one dimension, in two dimensions or in all three dimensions.

Composites made from particles of nano-size ceramics or metals smaller than 100 nanometers can suddenly become much stronger than predicted by existing materialsscience models. For example, metals with a so-called grain size of around 10 nanometers are as much as seven times harder and tougher than their ordinary counterparts with grain sizes in the hundreds of nanometers. The causes of these drastic changes stem from the weird world of quantum physics.

NANOMATERIALS

Nanomaterials is a field that takes a materials science-based approach to nanotechnology. It studies materials with morphological features on the nanoscale, and especially those that have special properties stemming from their nanoscale dimensions. Materials that have one dimension in the nanoscale are layers, such as a thin films or surface coating. Materials that are nanoscale in two dimensions include nanowires and nanotubes. Materials that are nanoscale in three dimensions are particles. Nanocrystalline materials, made up of nanometre-sized grains, also fall into this category. Nanoscale in Two Dimensions Two dimensional nanomaterials such as tubes and wires have generated considerable interest among the scientific community in recent years. In particular, their novel electrical and mechanical properties are the subject of intense research a) CARBON NANOTUBES (CNT)

CNTs are extended tubes of rolled graphene sheets. There are two types of CNT: single-walled (one tube) or multi-walled (several concentric tubes). CNTs have assumed an important role in the context of nanomaterials, because of their novel chemical and physical properties. They are mechanically very strong, flexible , and can conduct electricity extremely well. All of these remarkable properties give CNTs a range of potential applications.

b) Inorganic nanotubes and nanowires

Inorganic nanotubes and inorganic fullerene-like materials based on layered compounds such as molybdenum disulphide were discovered shortly after CNTs. They have excellent tribological (lubricating) properties, resistance to shockwave impact, catalytic reactivity, and high capacity for hydrogen and lithium storage. Nanowires are ultrafine wires or linear arrays of dots, formed

by self-assembly. They can be made from a wide range of materials. Semiconductor nanowires made of silicon, have potential applications in high-density data storage, either as magnetic read heads or as patterned storage media, and electronic and opto-electronic nanodevices.

c) Biopolymers

The variability and site recognition of biopolymers, such as DNA molecules, offer a wide range of opportunities for the self-organization of wire nanostructures into much more complex patterns. The combination of one-dimensional nanostructures consisting of biopolymers and inorganic compounds opens up a number of scientific and technological opportunities.

NANOSCALE IN TWO DIMENSIONS

A) NANOPARTICLES

In nanotechnology, a particle is defined as a small object that behaves as a whole unit in terms of its transport and properties. Nanoparticles are often defined as particles of less than 100nm in diameter. Nanoparticles are of interest because of the new properties (such as chemical reactivity and optical behaviour) that they exhibit compared with larger particles of the same materials.

Examples that illustrates the nanoparticle layer The idol of Palani Andavar is said to have been made of Navapashanam. In recent times the scientists who attempted to determine the composition of a small sample of the material of the idol, were startled to find that it immediately sublimated when heated. Thus its composition remains a mystery to date. The traces of the substance are contained in the ritual offerings in which it is bathed. When these are returned and consumed by the devotee, their spiritual progress is enhanced .

b)Fullerenes ( carbon 60 )

A new class of carbon material was discovered called carbon 60 (C60),the experimental chemists who discovered C60 named it "buckminsterfullerene", in recognition of the architect Buckminster Fuller. Several applications are envisaged for fullerenes, such as miniature ball bearings to lubricate surfaces, drug delivery vehicles and in electronic circuits

\ c)Dendrimers and quantum dots

Dendrimers are spherical polymeric molecules, formed through nanoscale hierarchical selfassembly process. Nanoparticles of semiconductor are known as quantum dots. These two have very good electrical properties

SURFACE TO VOLUME RATIO One of the most valuable properties of nanostructures is the enormous surface-tovolume ratio that they exhibit. A significant number of technological advantages of nanomaterials is related to this property. Surface Area is Big! The smaller something is, the larger its surface area is compared to its volume. This high surface-to-volume ratio is a very important characteristic of nano particles. For example, imagine that you have a big block of ice with one-meter sides Volume ratio would be for something as small as bunch of nanoscale particles .The vastly increased ratio of surface area to volume makes interactions between the

surfaces of the particle very important . If some thing has more surface area ,there are more places for other chemicals to bind or react with each other.

The large surface area to volume ratio of nanoparticles opens many possibilities forcreating new materials and facilitating chemical processes. In conventional materials, most of the atoms are not at a surface; they form the bulk of the material.

APPLICATIONS OF NANOTECHNOLOGY

NANOMEDICINE

NANOMEDICINE is the medical application of nanotechnology. Current problems for nanomedicine involve understanding the issues related to toxicity and environmental impact of nanoscale materials CANCER : Nano robots are injected into humans through veins and it reaches the tumors. The surface to volume property of these nanorobots helps to bind with the cancer causing cells . At first these robots tries to control the activity of the cells and takes the full metabolism of the cell under its control. Then it tries to kill the cancer cells and destroys its itself . But this method is still under examination. This concept will surely work out , in order to destroy the dreadful disease causing cells. MEDICAL NANODEVICES would first be injected into a human body, and would then go to work in a specific organ or tissue mass. The doctor will monitor the progress, and make certain that the nanodevices have gotten to the correct target treatment region.

The doctor will also be able to scan a section of the body, and actually see the nanodevices congregated neatly around their target. EXPLANATION OF NANO ROBOTS KILLING THE TUMORS.

REGENERATION Unlike other cells in the body, once cells in the central nervous system (spinal cord or brain cells) are mature, they cannot reproduce themselves like other cells can. If these cells are damaged through accident or disease, patients must learn to live with the impact. Nanotechnology provides a gel that spurs the growth of nerve cells. The gel fills the space between existing cells and encourages new cells to grow. While still in the experimental stage, this process could eventually be used to re-grow lost or damaged spinal cord or brain cells. Researchers are also investigating the use of nanotechnology to keep the body from rejecting artificial parts, and to stimulate the body to regrow bone and other types of tissue.

DETECTION AND DIAGNOSIS

Some diseases do not exhibit recognizable symptoms until they are well advanced. Often the earlier the disease is detected the better the benefits of treatment. One of the goals of researchers working at the nanoscale is to develop tools that will enable doctors to detect life threatening diseases before they overwhelm the body.

DRUG DELIEVERY AND TISSUE ENGINEERING

Nanotechnology has been a boon for the medical field by delivering drugs to specific cells using nanoparticles. The overall drug consumption and side-effects can be lowered significantly by depositing the active agent in the specific region only and in no higher dose than needed. Example for drug delievery:Buckyballs can "interrupt" the allergy/immune response by preventing mast cells (which cause allergic response) from releasing histamine into the blood and tissues, by binding to free radicals "dramatically better than any anti-oxidant currently available, such as vitamin E. Nanotechnology can help reproduce or repair damaged tissue. Tissue engineering makes use of artificially stimulated cell proliferation by using suitable nanomaterialbased scaffolds and growth factors. For example, bones can be regrown on carbon nanotube scaffolds. Tissue engineering might replace today's conventional treatments like organ transplants or artificial implants .

ENERGY EFFICIENCY

NASA revived fuel cell technology with new materials and used it on manned space flights. These new fuel cells were quiet, reliable, and clean, and produced water as a byproduct. It was an ideal scenario. The fuel cells produced both power and drinking water for the astronauts. Today, there are a number of different types of fuels cells under development.

EFFECTS OF NANOPARTICLES IN ENVIRONMENT

If the nanosensors and nanomaterials becomes a every day part of the buildings to make them intelligent,what are the consequences of these materials on human beings? Effect of nanoparticles on health and environment: Nanoparticles may also enter the body if building water supplies are filtered through commercially available nanofilters. Airborne and waterborne nanoparticles enter from building ventilation and wastewater systems

Effect of nanoparticles on societal issues: As sensors become more common place,a loss of privacy may result from users interacting with increasingly intelligent building components.The technology at one side has the advantages of new building material. The otherside it has the fear of risk arises from these materials. However, the overall performance of nanomaterials to date, is that valuable opportunities to improve building performance, user health and environmental quality.

AGRICULTURE ANS COSMETICS

Applications of nanotechnology have the potential to change the entire agriculture sector and food industry chain from production to conservation, processing, packaging, transportation, and even waste treatment. NanoScience concepts and nanotechnology applications have the potential to redesign the production cycle, restructure the processing and conservation processes and redefine the food habits of the people. One field of application is in sunscreens. The traditional chemical UV protection approach suffers from its poor long-term stability. A sunscreen based on mineral nanoparticles such as titanium dioxide offer several advantages. Titanium oxide nanoparticles have a comparable UV protection property as the bulk material, but lose the cosmetically undesirable whitening as the particle size is decreased.

CONCLUSION Thus nanotechnology is one of the most developing branches in science and has a millions of milestones to go. Its nature and special characters make us very amazing. It has a very wide applications various field especially in medicine that helps to kill even a dreadful cancer cells.