Ø Nanotechnology is defined as branch of material science which deals with the study of phenomena and manipulation of materials at atomic,molecular and macromolecular scale,where properties differ significantly from those at larger level.
Ø Bulk materials have continuous (macroscopic) physical properties but when particles assume at nanoscale dimension,the principles of classical physics are no longer capable of describing the behaviour (movement,energy) at these dimensions.
Ø The nanometre scale is conventionally defined as 1 to 100 nm,therefore nanoscience and nanotechnologies deal with clusters of atoms of 1 nm in atleast one dimension.
Ø Nanomaterial is an object that has at least one dimension in the nanometre scale. Nanomaterials can be categorized according to their dimensions .
All three dimensions < 100 nm
Two dimensions < 100 nm
One dimensions < 100 nm
Thin films,layers and coatings
Ø Nanomaterials can be of two types :
1. Non -intentionally made nanomaterials : belong naturally to the environment.( e.g. proteins,viruses)
2. Intentionally made nanomaterials : produced deliberately through a defined fabrication process.
NANOTECNOLOGY IN NATURE
Ø In nature we encounter some outstanding solutions to complex problems in the form of fine nanostructures with which precise functions are associated.
APPLICATIONS OF NANOTECNOLOGY
1.IN MEDICINE AND HEALTH CARE:
Ø The applications of nanotechnologies to the medical sector are known as nanomedicine. This area of nano techniques use nano materials to dignose,monitor,treat and prevent diseases. This includes cardiovascular diseases,musculoskeletal and inflammatory conditions,cancer,diabetes,psychiatric diseases and infectious diseases such as HIV.
Ø Diagnosis of a suspected disease is one of the most critical steps in healthcare and medicine. Diagnoses are wanted quickly, but must also be reliable, specific and accurate, and with the minimum risk of 'false positives'. Nano medicine has the potential to greatly improve the entire diagnostic process. Instead of collecting a blood sample in a vial and sending this to a specialised laboratory for testing(which can take days), doctors will be able to use miniaturised in vitro diagnostic devices in their surgeries.
Ø These are small but highly integrated devices capable of carrying out many test quickly at same time using very small quantities.
Ø These devices can measure ions, molecules or proteins or specific DNA sequences that are diagnostic for particular disease or disorder.
Ø Techniques such as X-ray, computer tomography (CT), ultra sound, magnetic resonance imaging (MRI) and nuclear medicine (NM) are widely use in medicines.
Ø Perfluorocarbon nanoparticles used as contrast agent for nuclear imaging, MRI and ultrasound.
Ø Fullerenes are also used in MRI.
Ø Nano technological therapy is based on drug development and targeted drug delivery. delivery systems also exist in the form of implants, inserts and other drug releasing systems.
Ø Nano technological therapy involves drug designing, screening and targeted drug delivery.
Targeted drug delivery
Ø Delivering therapeutic compound to the target site is a major problem in treatment of many diseases. A conventional application of drugs is characterized by limited effectiveness, poor bio distribution, and lack of selectivity.
Ø To overcome these problems targeted drug delivery system is in trends by using nano particles.
Ø Nano particles have been used as physical approach to improve and alter the working and efficiency of drugs.
Ø To increase efficiency and reduce the side effects of a drug a nano carrier is used which carry a specific drug to targeted area.
Ø Silica materials frequently used in controlled drug delivery systems are xerogels and mesoporous silica nanoparticles.
Ø Nano enabled technology will take the maximum share of market making nearly 70 - 90% market as it is safe, effective and without side effects. No wastage and increase bioavailability are going to be the basis of future drug delivery and treatments.
Ø In industrialised nations, the air is filled with numerous pollutants caused by human activity or industrial processes, such as carbon monoxide (CO), chlorofluorocarbons (CFC), heavy metals (arsenic, chromium, lead, cadmium, mercury, zinc), hydrocarbons, nitrogen oxides, organic chemicals (volatile organic compounds, known as VOCs, and dioxins), sulphur dioxide and particulates. The presence of nitrogen and sulphur oxide in the air generates acid rain that infiltrates and contaminates the soil.
Ø The high levels of nitrogen and sulphur oxide in the atmosphere are mainly due to human activities, particularly the burning of oil, coal and gas. Only a small portion comes from natural processes such as volcanic action and the decay of soil bacteria. Water pollution is caused by numerous factors, including sewage, oil spills, leaking of fertilisers, herbicides and pesticides from land, by-products from manufacturing and extracted or burned fossil fuels.
What can nanotechnologies do? Nanotechnologies offer the ability to control matter at the nanoscale level to create materials with specific properties that can serve specific functions.
Ø This is particularly important in environmental issues where pollution often arises from the presence of a specific contaminant within a mixture of materials, in solid, liquid or gas form. The small size of nanomaterials, together with their high surface-to-volume ratio, can lead to very sensitive detection. These properties allow the development of highly miniaturised, accurate and sensitive pollution-monitoring devices (nano-sensors). Nanomaterials can also be engineered to actively interact with a pollutant and decompose it into less toxic species. Thus, in the future, nanotechnology could be used not only to detect contaminated sites but also to treat them. Finally, this technology can be used to reduce the production of harmful wastes in manufacturing processes by reducing the amount of material used, and by employing less toxic compounds.
Ø Nanotechnologies offer many innovative strategies to reduce pollution in numerous processes including the reduction of waste in manufacturing processes, a reduction of the use of harmful chemicals, reduced emission of greenhouse-effect gases in fuel combustions and the use of biodegradable plastics. These are only a few of the many approaches that can be taken to reduce pollution of the environment. Nanotechnologies are already actively involved in this sector, either as a technology producing advanced materials that pollute less, or as a method to increase the efficiency of certain industrial processes (e.g. catalytic processes).
2.FUEL CELLS AND NANOTECHNOLOGIES:
Ø Nanotechnologies to impact energy capacity, battery power, charge rate and lifetime Current problems with lithium rechargeable batteries involve a number of issues, the first being the battery energy capacity: in order to allow ions and electrons to move quickly into and out of the active material (allowing fast charging and discharging), the material must be deposited as a thin film. This limits the amount of active material that can be incorporated into the battery (energy capacity).
Ø For high-capacity batteries, thickness is increased in order to provide more energy storage but with the drawback of slower charging.
Ø The second issue concerns the battery power: an important attribute of large format batteries is their capability to deliver power quickly. Power is restricted by the ion removal capability in lithium batteries which depends on the electrochemical properties of the battery. Then there is the problem of charge rate: batteries need to be recharged, and recharging times are now in the order of hours. The time of charge is restricted by the incorporation rate capabilities of Li+ inside the graphite electrode.
Ø Nanomaterials as alternatives to conventional electrodes.Nanocrystalline composite materials and nanotubes can be used to replace the conventional graphite or Li-graphite electrode. These can be fabricated to house voids having the same size as the lithium ions they have to accommodate. This allows much more active material to be packed into an electrode, increasing energy capacity.
Ø A nanostructured electrode with voids having the same size as the lithium ions increases the battery life and also ensures high charge rates. In the future, nanotechnology will also allow a move away from flat layers of electrode materials to positive and negative electrodes that interpenetrate. This 3D nano-architecture could improve the mobility of ions and electrons, hereby increasing battery power.
3.NANOTECHNOLOGY IN ENGINEERING:
Ø In engineering most benefits of nanotechnology depend on the fact that it is possible to tailor the essential structures of materials at the nano scale to achieve specific properties, thus greatly extending the well-used toolkits of materials science.
Ø Numerical simulation plays a critical role in exploring novel nanoscale structures, materials, devices and systems. Research in this area is focused on the development of physical models and computational methodologies to address a number of areas including emerging micro- and nanoelectronics, phase-change memory technologies, ultra-fast laser manufacturing, as well as the fundamentals of nanoscale thermal and fluid transport.
Ø In nano engineering the applications involved, nano based storage devices,nano chips,OLED (organic light emitting diodes).
4.NANOTECHNOLOGIES AND PURIFICATION OF AIR AND WATER:
Ø Nanotechnology is applied to make sensors to timely monitor what crops need more water and nutrients. Such nanosensors can measure water stress on plants in an individualised and localised manner. Each plant, root system or plot of land can then be given the exact amount of water it needs, thus rationalising the use of water.
Ø Zeolites: Zeolites are natural crystalline materials with pores having regular arrangements . They are also often used in the template synthesis of nanomaterial. They can also be used to prepare organised structures of a certain material to confer new optical properties on it. For instance, selenium can be incorporated into the channels of mordenite, a natural zeolite. The difference between a mordeniteselenium crystal and a natural selenium crystal is noteworthy: the optical absorption spectrum is considerably shifted to higher energies for the mordenite-selenium crystal. Zeolites are used in purification of permanentaly hard water.
Ø Aerogels: Silicon dioxide (SiO2) is the main component of quartz. It is chemically robust and finds widespread applications. In commercial products, it appears as an additive in rubber products for vehicle tyres but it is also the component of new types of aerogels. Generally, an aerogel is considered as a solid with up to 95 % of the volume consisting of nanoscale pores. Aerogels are manufactured with a sol-gel technique and can be made of carbon, metal oxide, polymers or silicates.
Ø Due to their high porosity, aerogels have an extremely high surface area and very low thermal conductivity. Thus they are suitable for thermal insulation and as filter materials. Another prominent property is their low specific weight, making them interesting for lightweight construction.
Ø Aerogels are also interesting for their optical properties, namely high optical transparencies.
Ø Silica aerogels are made of pores of about 10 nm arranged in distances between 10 and 100 nm. They are resistant and chemically inert to liquid metals, heat resistant up to 1 200 °C and non-toxic, thus they have also biomedical applications, such as substrates for cell growth and analysis. One of the problems of SiO2 aerogels that needs to be addressed is that this material has to be expensively protected against humidity, since it is not water-resistant and suffers from a loss of stability and thermal conductivity once it gets wet.
5. NANOTECHNOLOGY IN AGRICULTURE:
Ø Nano technology is now playing a crucial role in agriculture. Nano particles can be used in detection of enzyme substrate reactions to make effects more precise.
Ø Nano transporters are used to transport growth hormones,fertilizers,pesticides,insecticides more effecienly.
Ø Nano based chips and sensors can be used to detect pathogens and desease transmitters in pets and agricultural animals.
Ø Nano transporters can be used to make hybrids of seeds and animals by transporting DNA precisely.
Ø Nano particles can be used to enhance the quality and flavour of seed oils and edible oils.