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The world of the infinitely small | VeilleNanos

The world of the infinitely small

+ Info sheets

The domain of the infinitely small

By the AVICENN team – Last modification February 2023

What infinitesimal are we talking about?

Nanotechnologies: making and manipulating nano-objects

Nanotechnology refers to the processes of manufacturing and/or manipulating structures at the nanometric scale (nm), that of the infinitely small:

They are at the molecular and atomic scales. As an indication :

  • some viruses are a hundred nm in diameter
  • human DNA is 2 nm wide,
  • and a carbon or hydrogen atom measures 0.1 nm

The term “nanotechnology” was coined in 1974 and began to develop in the 1980s with the creation of the scanning tunneling microscope and the atomic force microscope.

Diagram from Kali magazine, December 2021

What is a nano-object?

Nano-objects or nanoparticles are like nano-grains but can have very different forms (wires, platelets, particles or nanoporous substances) and are generally grouped together, especially in powder form.

From a chemical point of view, to simplify, they are different from “classical” substances in two ways:

  • first, their size: these particles are of very small dimension because they are at the nanometric scale
  • then, nanoparticles and nanomaterials have different properties from those of conventional materials: they can change color or become more conductive, more solid, more photocatalytic for example.

Manufactured nanomaterials

Manufactured nanomaterials are man-made materials at the nanoscale that have “extraordinary” properties (in the true sense of the word) compared to materials structured at the micro- or macroscopic scale.

They are different:

Despite their differences, engineered nanomaterials and ultrafine particles (UFPs) share many commonalities, particularly in terms of challenges concerning tools to detect, measure and characterize them or to evaluate their risks3Cf. Nanomaterials Versus Ambient Ultrafine Particles: An Opportunity to Exchange Toxicology Knowledge, Stone V et al, Environmental Health Perspectives, 125(10), 2017.

While there are already several hundred different substances marketed at the nano scale (more than 300 are registered in the French r-nano register and also listed on the European nanomaterials observatory), the vast majority of nanomaterials used by industry belong to the following four categories:

They are most commonly found in the form of ultra-fine powders (in creams, lotions, sprays, dressings…), to which humans or the environment can be directly exposed.

They can be incorporated into solid materials (such as carbon nanotubes in bicycle frames), in which case they do not come into direct contact with humans or the environment during their use, but potentially during their production or during the degradation of the products at the end of their life cycle.

Specific properties

Indeed, the interest and the increasing development of nanomaterials can be explained by the specific properties that can be created by modifying matter at the nanometric scale, in particular the size or other physicochemical characteristics of materials.

At the nano scale, the material deploys new or more marked properties, notably because of their small size, which gives them a larger reaction surface than the same non-nanometric material. Why? Because the proportion of atoms on the surface (compared to the volume) is greater than for larger materials, allowing for greater exchanges and interactions with their environment4See for example:
Nanoparticles: Is Toxicity a Concern? D R, Rao P. EJIFCC, December 2011
Reactivity of inorganic nanoparticles in biological environments: insights into nanotoxicity mechanisms. Casals E, Gonzalez E, Puntes VF , Journal of Physics D: Applied Physics, 2012

Two images to understand this “size effect“:

  • visualize the surface covered by the contents of a spoonful of cocoa powder spilled on the table: it is equivalent to the surface of a whole chocolate bar
  • cocoa powder melts faster in milk than large squares of chocolate

Also, nanomaterials are more “reactive” than non-nano materials.

At the industrial level, these new properties of nanomaterials are perceived as opportunities in many fields of application, hence the growing number of releated patents each year5See for example:
Nanotechnology Published Patent Applications in USPTO: Number and Annual Growth Rate during the Past 20 Years, StatNano, December 30, 2020
Nanomaterials with the Highest Number of Granted Patents in USPTO, StatNano, November 25, 2020
Nanotechnology patents in USPTO (Patent), StatNano (accessed November 2020)

A sunscreen containing nanoparticles of titanium dioxide (TiO2) is more transparent than a “classic” cream whose TiO2 is not nano, thus avoiding white deposits on the skin, which brands use as a selling point.

New properties, new markets

Most nanoproducts on the market today offer advantages due to the addition of nanoparticulate powders that give them new properties, with various benefits:

  • elimination of bacteria (and bad smells) for nanosilver, used in textiles, bandages, disinfectant sprays, coatings for refrigerators, keyboards, food packaging…
  • strength and lightness for carbon nanotubes, which are a major asset, especially for the transportation industry
  • sunscreen or photo-catalytic effect (anti-pollution) for titanium dioxide nanoparticles which, depending on their effect, can be used in sun creams or cements
  • anti-caking and therefore fluidizing effect for nanosilicas used in foodstuffs, powdered sugar, table salts, etc.
  • catalytic effect (triggering of chemical reactions) for metallic nanoparticles, with applications in the health field
  • anti-fogging” effect obtained by laminating gold and titanium dioxide nanoparticles

Properties ++ > Risks ++ ?

New properties” also mean, potentially, “new risks”. Hence the need for an effective vigilance on these.

However, the resources dedicated to the monitoring and prevention of these risks are still not what they should be. That is why AVICENN is keeping watch!

Any questions or comments? This information sheet compiled by AVICENN is intended to be completed and updated. Please feel free to contribute.

Upcoming Nano Agenda

The invisible pollution of nanoparticles (Sur les épaules des géants, Le Havre)
Le Havre
Civil Society Conference on International Chemicals Management (SAICM, Bonn)
Behind the scenes in nanotechnology (Médiathèque, Troyes)

File initially created in April 2011

Notes & références

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