TROVO®guard – The Next Level in Antimicrobial Protection
TROVO®guard is an antimicrobial product consisting of amorphous and porous glass micro-particles containing small amounts of zinc and silver. The silver provides outstanding protection against bacteria, fungi, algae and some viruses; zinc intensifies the antimicrobial protection in particular with regard to e.g. fungi and algae. The silver in the glass particles consists predominantly of silver ions along with some metallic silver. The fraction of elemental silver can be increased or reduced by variations in the manufacturing process.
2.What is meant by the term “antimicrobial product”?
An antibacterial product inhibits growth of bacteria and other undesired germs or kills them entirely. Antimicrobial substances have these effects not only on bacteria, but on fungi and yeasts as well.
3. What is the antimicrobial effect of TROVO®guard based on?
Growth of bacteria and other undesired germs takes place only in the presence of moisture. Moisture (either water-based liquids or humidity in the air) also causes release of silver and/or zinc ions from the doped glass particles. While elemental silver (Ag0) and zinc (Zn0) are not antimicrobially active, their respective ions (Ag+ and Zn2+) are active against a variety of germs. These released silver and/or zinc ions interfere with important cellular functions of microorganisms, preventing further cellular reproduction and the cells die off.
4. Against what microorganisms is TROVO®guard effective?
TROVO®guard is effective against bacteria (gram positive and gram negative), mildew fungi (aspergillus niger) and yeast cultures (candida albicans) as documented in laboratory experiments. The antibacterial effects are primarily attributable to the silver ions, while the zinc ions effectively control algae and fungi. This combined action sets TROVO®guard apart from conventional antimicrobial products.
5. How can I evaluate the antimicrobial effectiveness of a product incorporating TROVO®guard?
Some users of TROVO®guard check effectiveness in their products by self-developed test methods. Products with TROVO®guard can be tested accordance with JIS L 1902:2008 (suspension test), JIS Z 2801:2000 (film contact method) or ASTM E 2149-01 (Dynamic shake flask method). The Agar diffusion test is not suitable for evaluating TROVO®guard since it is non-leaching, i.e. products formulated with TROVO®guard do not emit appreciable quantities of silver ions into their surrounding environment.
6. What concentration of TROVO®guard is required in products for antimicrobial protection?
Normally TROVO®guard is used in polymer products in percentages ranging between 0.1 and 2.0 wt %. The exact level used depends on the specific product considered and the expected application conditions. When protecting multilayer products, TROVO®guard may be used in the outer layer only. Design and development of products incorporating TROVO®guard should be accompanied by antimicrobial efficiency testing relevant to the specific application at hand.
7. What is the difference between TROVO®guard and other silver-based antimicrobial products?
a) The silver in the porous, amorphous glass particles of TROVO®guard consists primarily of silver ions and to a much lesser extent metallic silver. Silver ions are ideally suited for quick release into moist environments. Other silver-based antimicrobial products (such as silver nano- or microparticles) release silver ions at a much slower rate (in accordance with metallic silver’s low solubility). Therefore these products normally contain a silver salt additive or organic biocide to initiate microbiocidal action. Due to its porous nature, TROVO®guard provides ion release governed primarily by diffusion and not by solubility equilibrium. Long-term effectiveness is ensured by the metallic silver nanoparticles present in the pores along with the silver ions. The long-term effect is also provided by slow solvation of the glass particles due to contact with humid air. The silver ion concentration released in this process exceeds that expected from the solubility equilibrium for elemental silver. The zinc ions contained in the glass are also released due to solubility of the glass, providing additional antimicrobial action e.g. against mildew fungi and algae.
b) TROVO®guard is available in three particle size grades with average particle sizes of 1 μm, 2 μm and 3 μm and maximum particle sizes of 6, 12 and 20 μm respectively. These silver-doped glass particles can be mixed effectively into a wide variety of polymers, as opposed to silver nanoparticles which tend to agglomerate and cannot be homogeneously distributed in many polymers.
8. What application fields can TROVO®guard be used in?
TROVO®guard provides ideal antimicrobial protection in a wide variety of polymeric products and coatings. It upgrades the value of products, particularly frequently touched products, by killing germs on their surfaces and therefore reducing the risk of infection. Applications which immediately come to mind include shopping carts, buttons of elevators and doorbells, hand rails and hand grips in public transportation vehicles, operating keys and buttons of machines of all types – i.e. any surface touched by many people.
Further applications of TROVO®guard are found in areas where people work in close quarters with high demands on hygiene, e.g. hospitals, clinics, doctors’ offices, daycare centres and nursing homes. TROVO®guard can also be used as a preservative agent e.g. in sealants and wall coatings to increase service life in moist environments of all kinds including kitchens, baths and food processing facilities.
Use in antibacterial fibres and/or fabrics and clothing made from them is another highly interesting application sector.
9. How does TROVO®guard affect product properties?
Since TROVO®guard provides highly effective antimicrobial protection at extremely low percentages, no property changes are expected in materials to which it is added. Test results document the benefits provided by its problem-free, homogeneous distribution in the basic material. In certain materials TROVO®guard can cause minor colour changes which may be disadvantageous depending on the specific application at hand.
10.Does TROVO®guard cause health hazards for humans?
Silver and zinc ions are harmful only to lower forms of life. They are nonhazardous for higher life forms including humans. Objects made of silver, including silver cutlery, silver jewelry etc., are part of our everyday environments. Zinc compounds are in fact widely used as nutritional supplements.
11. How quickly does the antimicrobial effect begin in products incorporating TROVO®guard?
The antimicrobial effect starts immediately upon contact with moist surroundings. The effects on algae and mildew is delayed somewhat, which is not necessarily a downside given the fact that these microorganisms require a certain length of time to develop.
12. How long does the antimicrobial effect last in products incorporating TROVO®guard?
Trials conducted with TROVO®guard show a pronounced reservoir effect - due to encapsulation of the silver and zinc in the porous glass matrix - which provides time release over extremely long periods. This sets TROVO®guard apart from conventional silver particles or coatings. The antimicrobial effects last at least for several years, in many cases much longer, depending on the specific application considered.