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					SONA COLLEGE OF TECHNOLOGY, SALEM- 5.

NANOTECHNOLOGY

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ABSTRACT
Nanotechnology, often referred to as the ―science of small,‖ is the engineering of materials at the atomic and molecular levels to create electronic devices and other devices, making it possible to build machines on the scale of human cells. Among the growing sectors of nanotechnology like, nanomachines, nanopowders, nanoinstruments, & nanobiotechnology. Nanobiotechnology has developed a lot. Nanobiotechnology with the help of nanomachines and nanodevices are coming out with flying colors. Nanodevices with the help of computer science do a lot in the medical field by the following ways. As a metal propellers to kill the cancerous cells. To provide oxygen and mitochondria. As biosensors to sense the changes taking place in the body. As nanocopters and biorobots roam inside the body to perform the task as programmed to heal the disease. To find the viruses present in the body. For the logical control of gene expression As nanoscissors to cut the nerve cells without causing any damage tissues. Carbon nanotube in x-ray for thermionic rays which are used at present In veterinary field. Real world application of Nanotech. These nanodevices are programmed by the computer, which are very small and they sent into the human body and animals. They perform the particular task as being programmed; check the inputs and it gives the precise output. After performing the

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given task, they disintegrate and they pass into the blood stream as waste products and thereby they leave the body.

INTRODUCTION
Nanotechnology, "the manufacturing technology of the 21st century," should let us economically build a broad range of molecular machines. Nanotechnology is going to be flourishing in various sectors especially in the medical field which is shown in the following pie chart. So let us see them in detail. Computer technology has developed a lot in the field of nanotechnology with the help of nanodevices programmed; they are inserted into the body, do miracles and save thousands and thousands of mankind without causing any harm to them. It will let us build fleets of computer controlled molecular tools much smaller than a human cell and built with the accuracy and precision of drug molecules. Such tools will let medicine, for the first time; intervene in a sophisticated and controlled way at the cellular and molecular level. They could remove obstructions in the circulatory system, kill cancer cells, or take over the function of sub cellular organelles. Just as today we have the artifical heart, so in the future we could have the artificial mitochondrion. Until recently, nanotechnology was primarily based in electronics, manufacturing, supercomputers and data storage. Already, nonscientists are manufacturing new kinds of coatings for windows, cars, machines, planes, new materials for making fabric, and new circuits for computers. Scientists say the most immediate impact of nanotechnology will be the development of technology in the area of biomedical science, such as new drug delivery

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techniques, early detection of cancers, new diagnostic and treatment technologies and much more.

NANODEVICES IN THE BIOTECHNOLOGICAL FIELD:
Nanomachines offer humanity hope for the future. The idea that we could one day cure diseases, fix the atmosphere, and reduce poverty in the world is an exciting one. If scientists can overcome the technical difficulties involved in producing nanomachines capable of these goals, then the fruits of their efforts will benefit us all. Let’s see the nanodevices developed in this field.

SMALL COMPUTER KILLING CANCEROUS CELLS:
With the help of a small device we will be able to kill cancer cells. The device would have a small computer, several binding sites to determine the concentration of specific molecules, and a supply of some poison which could be selectively released and was able to kill a cell identified as cancerous.
Some scientists envisage tiny machines

The cancer killing device suggested here could incorporate a dozen

roaming the body to cure disease

different binding sites and so could monitor the concentrations of a dozen different types of molecules. The computer could determine if the profile of concentrations fit a preprogrammed "cancerous" profile and would, when a cancerous profile was encountered, release the poison. Beyond being able to determine the concentrations of different compounds, the cancer killer could also determine local pressure. As acoustic signals in the megahertz range are commonly employed in diagnostics (ultrasound imaging of pregnant women, for example). The cancer killer could readily be reprogrammed to attack different targets (and could, in fact, be reprogrammed via acoustic signals transmitted while it was in the body). This general architecture could provide a flexible method of destroying unwanted structures (bacterial infestations, etc).

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A DEVICE FOR PROVIDING OXYGEN:
A second application would be to provide metabolic support in the event of impaired circulation. Poor blood flow, caused by a variety of conditions, can result in serious tissue damage. A major cause of tissue damage is inadequate oxygen. A simple method of improving the levels of available oxygen despite reduced blood flow would be to provide an "artificial red blood cell." As oxygen is being absorbed by our artificial red blood cells in the lungs at the same time that carbon dioxide is being released, and oxygen is being released in the tissues when carbon dioxide is being absorbed, the energy needed to compress one gas can be provided by decompressing the other. The power system need only make up for losses caused by inefficiencies in this process. These losses could presumably be made small, thus allowing our artificial red blood cells to operate with little energy consumption.

ASPHYXIA:
Respirocytes make breathing possible in oxygen-poor environments or in cases where normal breathing is physically impossible. Prompt injection with a therapeutic dose, or advance infusion with an augmentation dose, could greatly reduce the number of choking deaths (~3200 deaths/yr in U.S.) and the use of emergency tracheostomies, artificial respiration in first aid, and mechanical ventilators. The device provides an excellent prophylactic treatment for most forms of asphyxia, including drowning, strangling, electric shock (respirocytes are purely mechanical), nerveblocking paralytic agents, carbon monoxide poisoning, underwater rescue operations, smoke inhalation or firefighting activities, anesthetic/barbiturate overdose, confinement in airtight spaces (refrigerators, closets, bank vaults, mines, submarines), and obstruction of breathing by a chunk of meat or a plug of chewing tobacco lodged in the larynx, by inhalation of vomitus, or by a plastic bag pulled over the head of a child. Respirocytes augment the normal

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physiological responses to hypoxia, which may be mediated by pulmonary neuroepithelial oxygen sensors in the airway mucosa of human and animal lungs.

A DEVICE FOR PRODUCING ARTIFICIAL MITOCHONDRIA:
"Every cell of the body contains many tiny organelles called mitochondria. These mitochondria produce most of the energy used by the body.‖ While providing oxygen to healthy tissue should maintain metabolism, tissues already suffering from ischemic injury (tissue injury caused by loss of blood flow) might no longer be able to properly metabolize oxygen. In particular, the mitochondria will, at some point, fail. The cellular function must be restored. The devices restoring metabolite levels, are injected into the body, are able to operate autonomously for many hours (depending on power requirements, the storage capacity of the device and the release and uptake rates required to maintain metabolite levels). Autonomous molecular machines, operating in the human body, could monitor levels of different compounds and store that information in internal memory. They could determine both their location and the time. Thus, information could be gathered about changing conditions inside the body, and that information could be tied to both the location and the time of collection. These molecular machines could then be filtered out of the blood supply and the stored information could be analyzed. This would provide a picture of activities within healthy or injured tissue. This new knowledge would give us new insights and new approaches to curing the sick and healing the injured.

BIOSENSORS:
A team of Australian researchers managed to build a functioning nanomachine, a biosensor, a combination of biology and physics, designed to detect substances with extreme sensitivity. It consists of a synthetic membrane chemically tethered to a thin metal film coated onto a piece of plastic. This membrane behaves like the outer skin of the cells of the human

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body in its ability to sense other molecules. The central component of the device is a tiny electrical switch, an ion-channel, only 1.5 nanometers in size.

Being cheap and easy to use, the biosensors have a huge range of potential uses, e.g. detecting drugs, hormones, viruses, pesticides, gene sequences, drugs, medically-active compounds, and more.

TEST-DRIVE FOR NANOCOPTERS:
The first microscopic "helicopters", which could one day carry out medical tasks inside the body, have been built and test-driven by scientists at Cornell University. The devices are no bigger than a virus particle. They consist of metal propellers and a biological component attached to a metal post. The biological component converts the body's biochemical fuel, ATP (protein synthesis), into energy. This is used to turn the propellers at a rate of eight rotations per second. In tests the nano-helicopters' propellers for up to 2 1/2 hours. This is an important first step towards producing miniature machines capable of functioning inside living cells.

BIOROBOTS:
"An engineered full-genome DNA, once synthesized, could be placed inside an empty cell membrane - most likely a living cell from which the nuclear material had been removed. Used in medicine, these artificial biorobots could be designed to produce useful vitamins, hormones, enzymes or cytokines in which a patient's body was deficient, or to selectively absorb and metabolize into harmless end products harmful substances such as poisons, toxins, or indigestible intracellular detritus, or even to perform useful mechanical tasks.

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CLONABLE STRAND OF DNA THAT FOLDS INTO AN OCTAHEDRON:
A group of scientists at The Scripps Research Institute has designed, constructed, and imaged a single strand of DNA that spontaneously folds into a highly rigid, nanoscale octahedron that is several million times smaller than the length of a standard ruler and about the size of several other common biological structures, such as a small virus or a cellular ribosome. Making the octahedron from a single strand was a breakthrough. Because of this, the structure can be amplified with the standard tools of molecular biology and can easily be cloned, replicated, amplified, evolved, and adapted for various applications. This process also has the potential to be scaled up so that large amounts of uniform DNA nanomaterials can be produced. These octahedra are potential building blocks for future projects, from new tools for basic biomedical science to the tiny computers of tomorrow. Folding the DNA into the octahedral structures simply required the heating and then cooling of solutions containing the DNA, magnesium ions, and a few accessory molecules. And, indeed, the DNA spontaneously folded into the target structure. Possible applications include using these octahedra as artificial compartments into which proteins or other molecules could be inserted

NANODEVICES TARGET VIRUSES:
By chemically coating the cantilever with a layer of antibodies that are sensitive to a specific virus, the Cornell team has now used the same device to detect viruses To do this, the cantilevers are immersed in a liquid containing the virus particles, which then stick to the device. The device is then removed from the liquid and the frequency is measured again."The sensitivity is high and just a few virus particles can be identified and detected rapidly."

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Meanwhile, Lieber's team converted an array of nanowire-based field effect transistors (FETs) into a virus detector by coating the surfaces of the transistors with antibody receptors 17. Viruses were then introduced into arrays using micro fluidic channels. Since viruses are charged particles, they change the current flowing through the transistor of the FET because they change the concentration of charge carriers when they bind to the nanowires (figure 1). Moreover, modifying the different nanowires within the array with receptors that are specific for different viruses allows multiple virus strains to be detected at the same time. Nanostructures such as cantilever beams and nanowire sensors will also play a large role in the early detection of disease and in gauging therapeutic efficacy, Ferrari said. Cantilever beams, which act as microelectronic mechanical systems on the nanoscale, can detect the tiny forces that occur with binding events. The beams and the nanowire sensors can be used to detect the presence of certain proteins and/or quantify amounts that may indicate diseases. Figure 1

AN AUTONOMOUS MOLECULAR COMPUTER FOR LOGICAL CONTROL OF GENE EXPRESSION:
Early biomolecular computer research focused on laboratory-scale, human-operated computers for complex computational problems. Recently, simple molecular-scale autonomous programmable computers were demonstrated allowing both input and output information to be in molecular form. Such computers, using biological molecules as input data and biologically active molecules as outputs, could produce a system for 'logical' control of biological processes. Here we describe an autonomous biomolecular computer that, logically analyses the gene therapy. Gene-therapy has focused the attention of the scientific community since it could be an efficient new way to cure several major human diseases such as cancer, AIDS, cystic fibrosis, anemia or progeria. The concept of gene therapy is the substitution in the cell nucleus of abnormal genes causing diseases by normal healthy DNA sequences.

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The main challenge in gene therapy is the design of specific carriers, which allow efficient delivery of the healthy genes in the cell (transfection). Such carriers should be able to transport DNA in the bloodstream, to cross efficiently cell membranes and to free the genetic material near the cell nucleus.

The goal of this project is to study the synthesis, characterization and clinical applications of new non-viral polymer gene carriers based on cationic polymers such as polyethyleneimine (PEI) or poly (vinyl amine). Such polycations form soluble complexes with DNA in aqueous solution, and therefore allow to transfer genetic materials inside cells. The chemical modification of the raw polymer (modification with specific cell-targeting ligands or water soluble polymers) allows an improved transfection efficiency and gene expression

The goal of this project is to study the synthesis, characterization and clinical applications of new non-viral polymer gene carriers based on cationic polymers such as polyethyleneimine (PEI) or poly (vinyl amine). Such polycations form soluble complexes with DNA in aqueous solution, and therefore allow to transfer genetic materials inside cells. The chemical modification of the raw polymer (modification with specific cell-targeting ligands or water soluble polymers) allows an improved transfection efficiency and gene expression.

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NANOPORE SENSOR:
Applied voltage draws a DNA strand and surrounding ionic solution through a pore of nanometer dimensions. The various DNA units in the strand block ion flow by differing amounts. In turn, by measuring these differences in ion current, scientists can detect the sequence of DNA units. Atomistic scale simulations performed on the NASA Columbia supercomputer (SGI Altix3000) allow detailed study of DNA translocation to enhance the abilities of these sequencers. Solidstate nanopores offer a better temporal control of the translocation of DNA, and a more robust template for nano-engineering than biological ion channels. The chemistry of solidstate nanopores can be more easily tuned to increase the signal resolution. These advantages will results in real-time genome sequencing. Potential applications for NASA missions including astronaut health, life detection and decoding of various genomes.

NANO-SCISSORS LASER SHOWS PRECISE SURGICAL CAPABILITY:
Pair of tiny ―nano-scissors‖ is able to cut, for example, nanosized units like nerve axons, the parts of nerve cells that carry nerve impulses away from the cells to muscles or to other cells. ―This tool opens up a new frontier for biologists studying nerve regeneration,‖ says Ben-Yakar. ―We can also apply it to many other studies that require nanosurgery, so it’s a very versatile tool.‖ The beauty of this laser, she says, is its ability to cut organelles (parts of cells—they are what organs are to organisms) precisely, without damaging surrounding tissue. Usually, conventional lasers used in surgery heat the area to be cut, then cut it, but this heightens the risk for tissue damage.

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Once cut, the axons vaporized, and no other tissue was harmed. Until now, researchers have only been able to investigate nerve regeneration in mice and zebrafish, which have complex nervous systems. This laser allows researchers to study nerve cells at their most basic evolutionary form, opening the door to other experiments on genetic and molecular factors that determine whether damaged nerve cells regrow.

CNT –BASED X-RAY:
Most diagnostic tools require tube current in the order of 10-100 mA and operating voltage in the range of 30-150 KV which was difficult to accomplish for the field emission x ray tubes. CNT –based –x-ray tube which can generate sufficient x-ray flux for diagnostic imaging applications. The device given above comprises a field emission cathode, agate electrode and a metal target in a vaccum chamber with a window. The cathode is a single walled nanotube (SWNT) film deposited on a metal substrate. A relatively low voltage is applied between the gate and the cathode to extract electrons from the cathode. The field emitted electrons are accelerated by a high voltage applied between the anode and the gate. A total emission current as high as 30mA is obtained from a small CNT cathode. The device can readily produce x-ray wave forms with programmable pulse width and repetition rate. Pulsed x-rays with a repetition rate up to 30 KHZ have been generated by applying an external triggering voltage on the gate. The x-ray flux is sufficient to image human extremity. The CNT –based- x-ray sources have several advantages compared to the thermionic X-ray tubes .the lifespan of the x-ray tubes can potentially be prolonged by eliminating the thermionic cathode. The size of the x-ray tube can be reduced significantly. It has also the ability to produce focused electron beams with the very small energy spread and programmable pulse width with repetition rate. This cnt –based cold cathode x-ray technology can potentially lead to portable and minature x-ray sources for industrial and medical applications.

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VETERINARY FIELD:
In the veterinary field also, the nanotechnology has grown a lot just as in humans. One of the most important and promising areas of medical research of today is the study of nanomaterials known as dendrimers. They are synthetic polymers, a thousand times smaller than cells. Dendrimers can be synthesized in various predetermined sizes and can interact with biological agents by modifying their surfaces properties. Three very important properties of dendrimers make then an excellent candidate as pharmacological agents. First, they can hold drug’s molecules in their structure and serve as a delivery vehicle. Second, they can enter cells very easy and release drugs right on target. Third and most important, dendrimers don’t trigger immune system responses. Dendrimers have a lot to offer to the field of Veterinary Medicine. In the future one of the major contributions of these synthetic nanomaterials will be the diagnoses, treatment and eradication of malignant tumors that commonly affect the small animal geriatric population. Some scientists envision the possibility of injecting quantum dots into the animal bodies. Quantum dots offer many technical advantages over traditional fluorescent dyes, which are commonly used to detect and track biological molecules. They not only can stay lit for a prolong period of time, they are also brighter and easier to visualize than organic dyes. They can be very helpful to visualize cell pathways, which is essential for our understanding of how certain drugs are going to behave in the animal’s body. In addition to their usefulness in identifying and tracking molecules, they promise faster, more flexible and less costly tests for clinical analysis. Those whom work in the veterinary field are familiar with immunoassay testing. Immunoassay technology capitalizes on the characteristic way that antibodies attach themselves to invading pathogens in the body. Antibodies recognize and bind to antigens with great specificity. One of the diagnostic applications of this behavior exhibited by antibodies is the conventional immunoassay. In a routine immunoassay test we expose a solution, such as blood plasma for example, to a tray containing antibodies that bind with a specific antigen under investigation. When the antibodies bind to the antigen, the test changes color. This system is used to identify and diagnose various conditions that afflict the animal population.

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REAL WORLD APPLICATION OF NANOTECH:

1 - Organic Light Emitting Diodes (LEDs) for displays 2 - Photovoltaic film that converts light into electricity 3 - Scratch-proof coated windows that clean themselves with UV 4 - Fabrics coated to resist stains and control temperature 5 - Intelligent clothing measures pulse and respiration 6 - Bucky-tubeframe is light but very strong 7 - Hip-joint made from biocompatible materials 8 - Nano-particle paint to prevent corrosion 9 - Thermo-chromic glass to regulate light 10 - Magnetic layers for compact data memory 11 - Carbon nanotube fuel cells to power electronics and vehicles 12 - Nano-engineered cochlear implant

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CONCLUSION:
Nanotechnology will be a strategic branch of science and engineering for the next century, one that will have a fundamental impact on the health, wealth and security of the world. The potential for nanotechnology to transform so many aspects of human existence is without precedent. Scientists say the most immediate impact of nanotechnology will be the development of technology in the area of biomedical science, such as new drug delivery techniques, early detection of cancers, new diagnostic and treatment technologies and much more. Nanodevices offer humanity hope for the future. The idea that we could one day cure diseases, fix the atmosphere, and reduce poverty in the world is an exciting one. If scientists can overcome the technical difficulties involved in producing nanomachines capable of these goals, then the fruits of their efforts will benefit us all. Perhaps the most commonly asked question about nanotechnology is: how long will it take to develop? Although prediction is a risky business, nanotech is likely to come about "in the 2010 to 2020 time frame." Thus in the future we can expect a instrument –free surgery without any pain, loss of blood and time. Like this everything can be nanomised with the help of programming computer.

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REFFERANCE: www.research.ibm.com http://www.nsti.org/Nanotech2004/program.html http://www.sciam.com/nanotech/ http://www.nanotech.50megs.com/ http://www.keepmedia.com/Search.do?refinePubTypeID=0&criteria=nanotech &.x=23&.y=8 http://dallas.bizjournals.com/dallas/stories/2001/09/10/focus2.html?page=2 http://www.nano.gov/html/facts/society.html http://nanotechweb.org/nanomaterials/?CFID=3321546&CFTOKEN=87524108 www.sciencedaily.com

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