Nanoparticles (NP) are typically described as “particles sized between 1 and 100 nanometres” (one to 100 billionth of a metre). Such particles can have new, exceptional properties that offer unbounded opportunities. They can add extra strength to materials and objects, make solar cells work more efficiently, or direct medical drugs straight to the place where the human body needs them.
As a matter of fact, nanotechnology has truly become a key scientific and economic issue of modern society. Their promising properties explain their increased application in almost all sectors and an investments rush is currently going on.
Nanoparticles have different physical, chemical and structural properties from other ‘classical’ materials. As they are extremely small, they have a very important surface-area-to-volume ratio. A large number of their atoms is situated on their surface and they have therefore a high surface activity. This explains why nanomaterials can have different physical and chemical properties than the bulk material with the same chemical composition.
Their physical and chemical properties enable them, among others, to act as catalysts (accelerator/facilitator) in biochemical reactions, and they also define their biological activities. Moreover, owing to their tiny size, nanoparticles can intervene directly and use the metabolism of cells. More simply, nanoparticles can be assimilated and move inside cells, following the mechanism used by the cells themselves.
The specific biochemical and biokinetic (‘how they move through the body’) characteristics of nanoparticles are behind their biological applications in food, agriculture, medicine and toxicology. The shift in their biological activity (by comparison with the corresponding bulk materials) may be an advantage (antimicrobial and antioxidant activity, treatment support, penetration of the cell barrier to administer medication, etc.), a drawback (toxicity, oxidative stress, cell dysfunction, etc.) or even both at the same time.
The existing models and techniques used to assess the risks of nanoparticles and nanomaterials are not tuned enough to determine how harmful they are to people and the environment. There are indications that some nanoparticles show harmful properties, but the reason why they could be harmful remains unravelled. Of course, this certainly does not apply to all nanoparticles and nanomaterials.
The diversity of nanoparticles increases considerably, in parallel with the number of their applications. Their characteristics, and the risks relating thereto, depend on their chemical composition, physical characteristics (size, shape, stability, etc.), and the matrices in which they are found. As a consequence, measuring these properties is the key to control efficiently the risks inherent to the introduction of these new technologies.
