Nano Technology - Applications

FULLERENES

Fullerenes are carbon nanostructures which include nanotubes and bucky balls (more properly known as buckminsterfullerene, are spherical molecules composed entirely of carbon atoms). Synthesised by the

condensation of high-temperature carbon vapour, they have diameters ranging from a fraction of a nanometre to 100 nm. This is the material of the future with extraordinary properties to match. Carbon nanotubes, for example, conduct much better than copper and are 100 times stronger than steel, but one-sixth of the weight.

Applications: electronics, energy devices, highstrength materials, super-sensitive nano-sensors and ideal for catalyst support.

NANO DRUG ENCAPSULATION

Using a chemical process, drugs are encapsulated in biodegradable-polymer capsules 100 to 500 nm in diameter. Due to their small size the capsules are taken up by cells. The benefit is a reduction in dose frequency of medication due to the slow release of the drug.

Applications: delivery of TB, HIV/Aids and malaria drugs.

QUANTUM DOTS

A quantum dot is a semi-conductor (between conductor and insulator) with nano-dimensions. Quantum dots and nano phosphors exhibit unique optical, magnetic and electronic properties, due to the quantum confinement effect. Depending on their size, they absorb and emit different colours when  irradiated with photons or electrons.

Applications: used in biosensors which can be used to pinpoint disease in the body, solar cells and flat  panel displays and special coatings.

NANO COMPOSITES

By adding nanoparticles and nanostructures to a polymer, a nanocomposite is formed. These materials of the future can be super-strong, light, conducting and transparent. A nanocomposite can be much more transparent than a polymer containing

micron particles, which is opaque.

Applications: aeronautic and automobile industries scratch-resistant coatings; self-cleaning windows, fuel cells.

NANOPARTICLES

Nanoparticles can be produced chemically in high temperature reactors or through mechanical milling. They are mostly 10 to 100 nm in diameter and often agglomerated.

Applications: coatings, composites, solar cells and medicine. Silicon nanoparticles can be used for printed electronics3.

WATER PURIFICATION

Nanotechnology offers a low-cost and effective solution to the challenge of access to clean and safe water for millions of people in South Africa and the developing world. The technology holds the potential to radically reduce the number of steps,

materials and energy needed to purify water. Depending on the kind of water to be purified – ground, surface or waste water – nano-materials can be tailor-made with specific pore sizes and large enhanced surface areas to filter out certain unwanted

pollutants, such as heavy metals or biological toxins. For example, titanium oxide at nanoscale can be used to degrade organic pollutants. And silver nano-particles have the ability to degrade biological pollutants such as bacteria.

South African scientists are testing different kinds of membranes and filters based on carbon nanotubes, nanoporous ceramics, magnetic nano-particles and other nano-materials which could be used to remove water-borne diseases such as typhoid and cholera, as well as toxic metal ions, organic and inorganic solutes.

When coated with different compounds could be used to remove pollutants, including arsenic, from water. 

Nanosensors – Researchers are developing new sensor technologies that combine micro- and nanofabrication technology to create small, portable, and highly accurate sensors to detect chemical and biochemical parameters in water. Several research consortia are field testing devices that incorporate nanosensor technology to detect pollutants in water, and some expect to commercialize these devises.

HEALTH

In both diagnosis and treatment, nanotechnology holds the key to revolutionise health care, particularly in developing countries where access to effective health care is still a challenge for millions of people living in remote areas. In the field of diagnostics, nanotechnology promises quick, early and accurate detection of diseases.

Portable, but highly sensitive point-of-care test kits are under development which will offer all the diagnostic functions of a medical laboratory. Depending on how they are designed and the intended application, the hand held kits could be used to test for viruses, bacteria or hormones. Thus they will be able to test – simply and quickly – for infectious diseases such as malaria, cholera, HIV/Aids and other sexually-transmitted infections, and even cancer. Also known as the “lab-on-a-chip” because of their ability to emulate the services of a complete medical laboratory, these inexpensive, hand-held diagnostic kits can pick up the presence of several pathogens at once and could be used for wide-ranging screening in remote clinics.

Biomedical imaging – Nanotechnology applications are in development that will radically improve medical imaging techniques.

For example, gold and silver nanoparticles have optical properties which make them extremely effective as contrast agents. Quantum dots which are brighter than organic dyes and need only one light source for excitation, when used in conjunction with magnetic resonance imaging, can produce exceptional images of tumour sites.

Nanomaterials are also used in therapeutics or treatment: Targeted drug delivery systems – Nanostructures can be used to recognise diseased cells and to deliver drugs to the affected areas to combat cancerous tumours, for example, without harming healthy cells. In obesity, nano --particles can target and inhibit the growth of fat deposits.

Slow-release drug therapy – Research shows that nano-sized biodegradable polymer capsules containing drugs for tuberculosis treatment are effectively taken up by the body’s cells.

The effect is a slower release of the drug into the body and a reduction in the frequency with which TB patients need to take his or her medication. In countries where drugs are not readily available and compliance is generally low due to a number of reasons, the technology holds great potential for increased drug compliance and less chance of the development of drug resistance. Photothermal and hypothermal destruction of cancer – Some nanoparticles, such as gold, possess therapeutic properties based on their magnetic wavelength or optical properties. They absorb light and heat up the surrounding area, killing the cancer cells.

ENERGY

Another impressive application for nanotechnology is energy production, conversion and storage. Research is well advanced enough to establish that nanotechnology offers a viable alternative to non-renewable fossil-fuel consumption and gives us the means to achieve a “hydrogen economy”. Nano-applications in this area include: solar cells; fuel cells and new energy production, conversion and storage processes. In all cases, the results are energy that is cheaper, cleaner, more efficient and renewable. In future, nano holds the potential to produce hybrid vehicles with reduced fuel consumption and a lighter motor weight.

INDUSTRIAL APPLICATIONS

Nanotechnology is set to add value to South Africa’s raw mineral resources through beneficiation of gold, platinum group metals and other minerals which are used as high performance catalysts, absorbents in polymer nano composites and in energy-saving materials.

Nanotechnology can produce cleaner process engineering which will in turn produce value-added chemicals and speciality products, including  bio catalytic systems and novel heterogeneous catalysts. Nanotechnology can make catalytic converters more efficient, cheaper and more accurately controlled. l Nanotechnology-based innovations can be designed that will combat air pollution remediation, detect toxic materials and leaks, reduce fossil fuel emissions and separate gases.

Advanced materials and manufacturing applications – the list is endless …

Nanotechnology can produce smart, functional materials, including lubricants and barrier coatings, ultra-hard and super-strong materials, electro and photo-chromic materials with applications in all manufacturing sectors, industry, medical and

domestic markets. Nanoparticles can also improve a wide range of properties shown by engineering plastics, such as bio-degradability and improved thermal, mechanical and electrical properties. Thus, plastic bags can be made to bio-degrade and

plastic car parts or building materials can be made more fire-resistant. Other areas include the development of nanoparticles for applications in phosphorous paints, printable electronics, inexpensive solar cells and nanotube synthesis for application in sensors and as catalyst support structures.