Temps de lecture :5 minutes
The term “nanotechologies” includes both objects (nanostructures, nanosensors, etc.) and manufacturing technologies such as nanoinstruments. With nanotechnologies, science makes the leap from Newtonian physics, which describes mainly the macroscopic world (visible to the naked eye), to quantum physics, which deals with the nanoworld: atoms and particles.
Nanometres and the nanometre scale
The prefix “nano” derives from the Greek nanos for “small”. Very small, in fact: a nanometre (nm) is one billionth of a meter. The nanoworld encompasses objects of 100 nm and under. The nanometre is the unit of length used to describe the size of molecules, while atoms are measured in tenths of nanometres (angstroms). To illustrate, one nanometre is about 1/30,000 the thickness of a hair. A grain of pollen measures about 5,000 nm, and a red blood cell 2,000 to 5,000 nm.
Nano-objects in daily life
Nano-objects are highly varied. They may take the form of powders (nanopowders), tubes (nanotubes), wires (nanowires) or hollow spheres (fullerenes). For several years, industry has produced them in large quantities. They are used to reinforce or coat other materials, or to modify physical or chemical properties.
Nano-objects can be found in many articles of daily life. Here are a few examples that illustrate the variety of ends they are used for:
– The walls of some refrigerators and dishwashers contain metal nanoparticles for antibacterial protection.
– Some sunscreens contain nanoparticles of titanium dioxide, of approximately 50 nm in size, which are capable of reflecting ultraviolet rays. Other nanoparticles impart waterproof properties to some creams. Finally, some new creams contain fullerenes which their manufacturers claim capture free radicals, the culprits behind wrinkles.
– In articles such as skis, tennis rackets, golf clubs, or bumpers, carbon fibres are increasingly replaced by the much more resistant carbon nanotubes.
– Clothing increasingly contains nanoparticles to impart waterproof or stain proof properties. The fibres of sport footwear, for example, may contain nanocontainers that release antibacterial substances. Nanopowders can also be used to make a textile flame-retardant.
– Some glass is now treated with metal nanocoatings to prevent penetration of infra-red rays and resulting heat. Nanobumps may also be formed on the surface of glass to make it water repellent: water flows smoothly over its surface, taking with it any dust in its path.
– In electronics, nanomaterials are used to enhance the performance of computers and mobile phones, which are manufactured on an ever-smaller scale.
The nano-objects of tomorrow: for whom, for what purpose?
Although still in the research stage, new nano-objects should make for important technological advances in the near future, in such fields as medicine, energy, the environment, electronics, and food, to name just a few areas where research has made the most progress. [Debate]
Carrying medicine to sick cells
The active ingredient of a given medicine must often overcome many obstacles before reaching its target. Much of it is wasted on healthy tissue which may suffer severe toxic side-effects. By developing nanoparticles capable of overcoming biological barriers and carrying active ingredients in a shell, nanotechnologies will make it possible to improve the bioavailability of medicine to sick organs or tissues. Researchers are also investigating treatment for some cancers using metal nanoparticles, which, associated with antibodies, could recognise and adhere to tumorous cells. They could then be heated to destroy these cells. [Debate]
Monitoring the environment
Nanotechnologies could give rise to new, ultra-sensitive sensors that would be better capable of detecting pollutants harmful to the environment and to human health. Nanosensors composed of metal nanoparticles coating a carbon surface already exist; they are used to detect such pollutants as heavy metals and some toxic gases. Research is on-going for other nanosensors intended for monitoring air quality in public places.
Producing, transporting and stocking energy
Hydrogen batteries and solar energy are the main fields of application for nanotechnologies. New nanopolymer-based cells are expected to increase output, which is currently very low for classic cells (around 15%). Nano-objects could also be used to convert electricity into hydrogen form, making it easier to stock. Finally, using nanotubes in electric power transmission lines will likely improve their efficiency.
Microelectronics aims to stock and process increasing amounts of information in a minimum of time through the greatest possible miniaturisation of its components. To reach this goal, researchers aim to fabricate nanocomponents from molecules, nanoparticles, carbon nanotubes, etc. [Debate]
Should nanotechnologies raise fears?
Nanotechnologies should contribute to an overall improvement in living conditions. But might they also present health and environmental risks?
Over the course of their lifetime, for example, nanostructures might release some particles which could upset ecosystems once in the environment. Some scientists believe that inhaled nanoparticles could enter the bloodstream or the central nervous system. They could also be toxic to the skin or other organs. To date, very few toxicological or epidemiological studies have been carried out on the effects of nanoparticles. Recent studies on carbon nanotubes using mice resulted in mixed findings: there were toxic side effects for some and no side effects for others.
Although it is generally conceded that nanoparticles are potentially more toxic than similar materials of a larger scale, this is still an area of major uncertainty. No one can today affirm that nanoparticles are either harmful or harmless to health and the environment.
Worldwide, many research projects have been launched to investigate the potential risks of nanomaterials. Ethics committees have been set up to reflect on these questions, and rules have been implemented to protect laboratory personnel who produce and handle nanoparticles.
Fantasies and myths
Works of science fiction depicting end-of-the-world visions of nanotechnology have sparked severe fears in this area. The first work in this genre, Engines of Creation, came out in 1986. Author Eric Drexler spins a tale of nanomachines capable of assembling atoms and manipulating matter at the molecular level; of reproducing without constraint; and therefore of destroying the world. Although the novel is based on real scientific knowledge, for the moment it is still firmly grounded in fiction. In view of the huge technological advances that would be required, manufacturing machines capable of reproduction will long remain far beyond the grasp of scientists.
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