1. Current Situation

Silver has found use as prevention or cure for centuries, in particular to target infections. It is well known that silver coins served to preserve various liquids during storage, such as water and milk already in ancient Rome and Greece. Currently, silver is used by NASA aboard the Space Station as a step in water purification.

Buněčná stěna E.Coli narušená stříbrem Silver is strongly bactericidal with effect observable from the concentration of 100 ppb (parts per billion). For the desired effects, silver ions need to reach the surface of bacterial cell. The higher the concentration, the stronger the effect is. Silver ions are reported to interact with enzymes of the respiratory chain, but also interact with DNA and break up the cell wall due to action of reactive oxygen species whilst the cells of human body do not show any damage. Solutions containing silver have been some of the first bacteriostatic agents in the treatment of wounds. However crystalline silver is badly soluble in water and acidic solutions do not produce silver of good properties for treatment and show low efficiency in surface wound treatment.

In the 1920, electrolysis was used to yield colloidal ionic silver and its use became very widespread. In the same year, colloidal silver was certified as an effective agent against bacteria.

In addition to the declared antibacterial effects, complicated wounds showed much better healing when silver was applied as well as lower signs of inflammation. After 1940, when systemic antibiotics (penicillin) started to get used, silver became less common. The post war period also showed development of silver ion complexes- such as nitrate and sulfadiazine as well as so called silver protein which were all meant to increase the local concentration of active silver. Similar preparations are still in use today as a local bacteriostatic.

More recently, scientific research has shown that properties of chemical compounds depend on their size. Nowadays, the self-standing discipline of nanotechnology studies properties of particles in the order of size of nanometers (one billionth of a meter, 10-9 m). one nanometer equates to roughly 10 atoms in width. Silver crystals made by common methods produce clusters of 100-900 nm in diameter. Novel nanotechnological approaches can yield much smaller particles. Small particles have got a very large surface area to volume ratio which vastly enhances the rate of chemical reactions taking place. Particles in the nanometer range show different physical properties to the bulk material also in other ways such as electrically or optically. Small size enables for use of small quantities whilst preserving activity, which is economical particularly when expensive metals – like silver – are used.

2. Expected developments

Nanočástice stříbraNanotechnology made bulk silver into a very effective biological agent. The dramatic improvement in antibacterial activity has already impacted microbiological research and more studies are being done to elucidate the anti-inflammatory properties. Silver has found use also in daily applications. Silver ions embedded in yarn finds use in antibacterial garments such as socks. Antibacterial activity in underwear helps to remove unpleasant odours which are a direct result of the proliferation of bacteria. Such products are already available on the market, including the Czech Republic. Other uses include creams, shoe insoles, surfaces of kitchen appliances (Samsung fridges and microwaves), food packaging and numerous other objects where antibacterial activity and mould suppression are desirable.