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According to the definition by the United States Nanotechnology Initiative, Nanotechnology is the understanding and control of matter at the nanoscale, at dimensions between approximately 1 and 100 nanometers". One nanometre is one-billionth of a metre. At the nanoscale, objects show different properties from those at a larger scale (Turner, 2008), and therefore nanomaterials are used in a variety of products and there are huge expectations for possible applications. However, due to the smallness of the size scale there are implications for health and environmental problems. This essay will describe the size scale of nanometre, what is special about the nanoscale, how applications benefit human life and implications for possible health and environmental problems.
First of all, it is important to instill a feel for the size scale, nanometre. There are several analogies to explain how small nanometre is in relation to size which can be seen with the human eye. A human hair, for example, is about 60 Î¼m thick which equals 60,000 nm (Wolf and Medikanda, 2012). To get down to a nanometre from a hair, it needs to be cut in half 16 times. Although it is impossible to see a nanoscale object, many nanoscale materials exist in living organisms. For instance, DNA is about 2.5 nanometres and haemoglobin is about 5 nanometres in diameter (NNI, 2011).
It is also important to understand what is special about the nanoscale. At this sale, objects behave in different ways from at a larger scale (Binns, 2010). For instance, iron is widely known as a magnetic material, however, a piece of Fe is not magnetised (Binns, 20120). This is because Newtonian theories collapse at the nanoscale and objects objects do become subject to quantum effects (Allhoff et al., 2010). This is also because the smaller particles are, the higher the surface area to volume ratio is (Binns, 2010). This means that materials made of nanoparticles have more surface to interact with other materials (Binns, 2010). The beneficial properties that materials have at the nanoscale include durability, magnetic properties, thermal conductivity and electrical conductivity (NNI, 2011).
Nanotechnology has already been applied for a variety of products. The following are some of applications. A carbon nanotubes is "a one-atom-thick graphene sheet" rolled up into a cylinder (Allhoff et al., 2010). Carbon nanotubes are physically very strong yet light (NNI, 2011). Furthermore, they can be flexible and bend to extreme angles when combined with polyethylene (Allhoff et al., 2010). To take advantage of these properties, carbon nanotubes are used in a variety of products including car bumpers, tennis racquets and balls and baseball bats (NNI, 2011). They are expected to replace more metal used in vehicles in order to improve the energy efficiency (NNI, 2011). Carbon nanotubes are also used in electrical circuits as they can conduct not only electricity but also heat well (NNI, 2011). Nanoscale silver can kill bacteria (Zhang et al., 2008) and is used in deodorant (NNI, 2010). Another application of nanoscale silver is polyurethane coated with Ag nanoparticles which are used as means of removing bacteria from drinking water (Zhang et al., 2008). Sunscreens contain nanoscale zinc oxide or titanium dioxide to reflect ultraviolet light (NNI, 2011). Many of electrical devices including computers and mobile phones contain quantum dots which is "zero-dimensional nanostructure" (Allhoff et al., 2010). Computers work on a group of bits which is related with transistors (Allhoff et al., 2010). Quantum dots can exist in both the zero and one state and calculate all the possible combinations of zero and one (Allhoff et al., 2010). This results in an increase in the power and memory of computers (Allhoff et al., 2010). Another application is stain-resistant fabrics. Water can dissolve many substances (Allhoff et al., 2010). This is because water molecules are electrically polar, and therefore negatively charged water attract positively charged molecules and vice versa (Allhoff et al., 2010). Non-polar molecules, also known as hydrophobic molecules, do not attract with water molecules and mix with water (Allhoff et al., 2010). By adding hydrophobic nanoparticles to regular fabrics, water-resistant and stain-free textiles can be made (Allhoff et al., 2010). Furthermore, nanofilms made of hydrophobic molecules are used on eyeglasses, mirrors and windows making them water-repellent, anti-fog and self-cleaning (NNI, 2011).
There are many expected applications yet to achieved. Traditional ways of forming small materials include pounding, carving, molding, cutting and chipping (Turner, 2008). This is known as top-down technology (Turner, 2008). The opposite of top-down technology is bottom-up technology (Turner, 2008). The minimum size that human beings can make using top-down technology is limited by the ability to cut, chip or mold. On the other hand, bottom-up technology enables scientists to design and manufacture far smaller materials than those humans can make by using top-down technology. Scientists expect to develop drug-delivery systems by combining fullerene, which is a sphere-shaped carbon material that consists of 60 carbon atoms, with other materials (Allhoff et al., 2010). Some scientists think that nanofood can make human feel fuller for a longer period of time, which would be a solution of obesity and starvation (The Royal Society, 2010). Researchers at Massachusetts Institute of Technology have succeeded to create an artificial leaf which is made of silicon with each sides coated with catalysts (Wolf and Medikonda, 2012). This uses solar energy and once the sunlight is absorbed by silicon, the catalysts change water into oxygen and hydrogen (Wolf and Medikonda, 2012). This hydrogen can be used to produce electricity (Wolf and Medikonda, 2012). Another thing under study is superconductors. There has been a great advance in ceramics which transfer electrons at 138 K without energy loss (Wolf and Medikonda, 2012). Scientists are trying to build a ceramic which can conducts electricity without losing energy at a far higher temperature. This could be applied for magnetic levitation trains (Wolf and Medikonda, 2012).
Along with positive impacts, nanotechnology may also have negative impacts on our health and the environment. Because of the smallness, there is a possibility that nanomaterials may slip into one's body cells or our food chain and cause undetermined effects (Allhoff et al., 2012). Once they are absorbed in the landfill, they could persist for a long time because of the durability nanomaterials have and the impacts are still unknown (Allhoff et al., 2012). Zhang et al. (2009) claims that more experiments on animals and knowledge of unique properties are needed in order to determine potential hazard in health, the environment and ecology, evaluate and manage risks. Although carbon nanotubes are already being used in many products, it may cause health problem once it is inhaled as they have asbestos-like fibres and are difficult to dislodge from one's lung (Allhoff et al., 2010). Allhoff et al. (2010) emphasise that further investigations should be done before nanoproducts enter the marketplace and law and regulations should be updated as scientists learn more about nanoscience or nanotechnology as nanomaterials may have unpredicted properties.
To sum up, at the nanoscale, materials have a variety of properties. By combining with other materials, the properties become more significant or other properties appear. These properties can be taken advantage to improve our lives or solve environmental issues. However, besides appealing properties, there might be unknown properties which can cause health or environmental issues. Therefore, it is important to invest in research on effects on human health and the environment as well as in research on new nanomaterials.