Nanosilver

Nanosilver is not a new discovery by nanotechnologists - it has been used in various products for over a hundred years,. The antimicrobial effects of minute silver particles, which were then known as "colloidal silver", were known from the earliest days of its use.

As early as the 19th century, minute silver particles were used, for example in antibacterial water filters.

Numerous nanomaterials are currently at the focus of public attention. In particular silver nanoparticles are being investigated in detail, both by scientists as well as by the regulatory authorities. The assumption behind this interest is that they are dealing with a completely new substance. However, nanosilver is by no means the discovery of the 21st century. Silver particles with diameters of seven to nine nm were mentioned as early as 1889. They were used in medications or as biocides to prevent the growth of bacteria on surfaces, for example in antibacterial water filters or in algaecides for swimming pools.

The nanoparticles were known as colloidal silver in those days, but now - extremely small particles of silver. The only new aspect is the use today of the prefix nano. "However," according to Bernd Nowack, "nano does not mean something new, and nor does it mean something that is harmful." When colloidal silver" became available on the market in large quantities in the 1920s it was the topic of numerous studies and subject to appropriate regulation by the authorities. Even in those days the significance of the discovery of nanoparticles and how they worked was realized. But that does not mean that the possible side-effects of nanoparticles on humans and the environment should be played down or ignored. It is important to characterize in exact detail the material properties of nanosilver and not just to use without verifying.

The term nanoparticle is understood to refer to particles whose dimensions are less than 100 nm. Because of their minute size nanoparticles have different properties than those of larger particles of the same material. For example, for a given volume nanoparticles have a much greater surface area, so they are frequently much more reactive than the bulk material. In addition, even in small quantities nanosilver produces more silver ions than solid silver. These silver ions are toxic to bacteria. Whether or not nanosilver represents a risk to humans and the environment is currently the subject of a great deal of investigation.