The Science

Silver Life Textiles:

Our technology-based products utilize Silver Life Textiles.

Antimicrobial textiles have significant potential uses in a range of industries including healthcare, air filtration, hospitality, sport, leisure and fashion as well as creating safe areas within vehicles and public transport.  Integration of an antimicrobial agent such as silver into textiles can prevent overgrowth of microbes, including fungi.  How the antimicrobial agent is applied to the textile, the nature of the textile and the method of application are all important considerations when selecting a suitable antimicrobial agent.

Silver impregnated textiles are becoming very popular because silver is a broad-spectrum antimicrobial agent with the ability to kill the majority of microbes at very low levels of concentration.  This means that silver can be used and yet be safe for animals and humans and, importantly, also for the environment.

Silver can be applied to textiles by coating the surface with silver salts, metallic silver, and nanoparticles.  Although these different methods of application result in high levels of activity, the silver can leech from the textile and potentially cause irritation and contamination of the environment.

Silver Life Textiles use a specific patented technology that integrates metallic silver into the polyester component of the textile.  This textile technology new and developed in the UK.  Laboratory studies have shown that the Silver Life Textiles are highly antimicrobial, rapidly killing a wide range of microorganisms including methicillin resistant Staphylococcus aureus and Clostridium difficile.  In comparison studies with other silver textiles the Silver Life products reduced micro-organisms numbers consistently more than those other products.  In addition, when the Silver Life Textiles are washed (up to 400 washes have been tested) antimicrobial activity is still observed with over a 99.9% reduction seen.

Silver Life Textiles can resist fungal and mould spoiling, so clothing and other fabrics will resist storage in humid conditions for long periods of time.

Silver Life Textiles in Face Coverings:

Wearing face coverings has become a normal practise during the recent pandemics such as SARS, MERS, H1N1 influenzae and most recently the pandemic with SARS-CoV-2.  However, face coverings are already being widely worn by many of us as a method of protection against the fine particles (particulates) contained in the existing air pollution events being experienced in our larger cities.

Face coverings are worn on the assumption that the wearer will gain protection from spreading and acquiring microbes including virus and bacteria as well as preventing the inhalation of particulate pollution.  However, many of the disposable face coverings currently available in the marketplace are designed solely for the purpose of restricting particle movements and even in that they may not be effective.  Many existing face coverings are rendered inactive when worn because moisture from breath dampens the textile and makes it more susceptible to transport of microbes from the surface, through the textile onto the second surface near the nose and mouth.  This increases the risk of infection.

Face coverings and (in the near future) snoods made with Silver Life Textiles negate this effect.  In fact, the Silver Life Textiles need moisture to activate and this is provided by the moisture content in your breath.  Clearly, our Silver Life Face Coverings should also be the face covering of choice when working outside in damp environments too!

Our 3-D knitted Silver Life Face Covering has the advantage of having the whole face covering made of the Silver Life Textile and having a proven ability to filter down to three microns.  Even the best, widely available face masks only filter down to ten microns.  As a protective covering against air pollution alone the Silver Life Face Covering is a winner.

The Silver Life Face Covering (and snood) should be washed according to your own personal hygiene cycle.  Washing can be undertaken, either:

  • Up to 60oC using biological or non- biological washing powder; or
  • In warm water using a hand wash and a suitable washing solution.

Tests have shown that the Silver Life Textiles are still active after 400 washes and our Silver Life Face Coverings are guaranteed up to 100 washes or two years of use. 

Tumble drying of our Silver Life Face Covering is not recommended.

How Silver Works:

All our original Silver Life products rely on the effectiveness of silver (Ag+) as a safe anti-microbial element.  We have provided this “Background Science supporting the Silver Life Product Range” to demonstrate the history and application of silver that we use in our barrier technologies.

So, how does silver work?

Silver (Ag+) was used to keep water fresh by the Ancient Greeks and Romans (Barillo & Marx, 2014).  Silver coins were also originally thrown into water fountains for the same reasoning.  The antimicrobial action of silver is dependent upon the bioavailability of the silver ion (Ag+). 

Silver has a broad spectrum of activity within microorganisms as:

  • It interferes with membrane permeability and the proton motive force (Schreurs and Rosenberg 1982; Dibrov et al. 2002).
  • It inhibits respiratory chain enzymes (Chappell and Greville 1954; Semeykina and Skulachev 1990), and inter-chelation with DNA (Rosenkranz and Rosenkranz 1972; Modak and Fox 1973; Teng et al. 2000).
  • It inhibits bacterial growth between 8 and 80 ppm, with Gram-negative bacteria having lower MICs than Gram-positive bacteria (Hamilton-Miller et al. 1993). It is noted that Gram negative bacteria have a different cell wall structure to Gram positive bacteria and they tend to be more difficult to treat with antibiotics because of the way they are transported into the cell.
  • It is more active against these bacteria - a very positive attribute.
  • It kills viruses by inhibiting various essential enzymes required for binding, replication and reproduction (Galdiero et al 2011).

There are three general groupings of silver products available. These are:

  1. Elemental or metallic silver in a natural crystalline state or as nanoparticles.
  2. Inorganic complexes – e.g. AgSD, AgNO3 and silver chloride, each with varying solubility.
  3. Organic complexes – colloidal silvers, silver proteins (Lansdown and Williams 2004).

The role of the carrier is very important, and incorporation into textiles will only show effect when there is moisture, as Ag+ is only active in solution.

How Do the Silver Life Textiles Work?

The Silver Life Textiles are a mix of cotton and polyester.  The polyester component within the textile contains metallic silver which has been finely ground.  The silver is encapsulated by a fully patented extrusion process.  The fibres are then woven or, in the case of our Silver Life Face Covering – 3D knitted into the polyester/cotton mix at varying concentrations (for example 90% cotton /10% polyester).

When the textile is used, for example in a face covering or bed linen or in towels, the areas that become moist will allow the silver to activate and the antimicrobial action will result.  Silver is inactive when the textile is dry.

When the Silver Life Textiles are washed, the polyester component will slowly lose fibres from the surface releasing more silver ions to the surface.  Studies have shown that the antimicrobial action occurs within the fabric and silver does not leech out into the surrounding environment.

Toxicology studies have shown minimal irritation and immunological responses.  This is because of the way in which the silver ions are held within the Silver Life Textiles.

Silver Life Textiles are Safe:

Reported cases of silver toxicity are limited.  Silver products have been intensively used over the past fifty years in the treatment of burns and it has been found that silver toxicity is insignificant compared to the benefits of use and also in comparison with other antimicrobial treatments.

A number of documented cases of systemic silver toxicity with argyria were reported in the early 1960s when uncontrolled levels of silver from AgNO3 were used.  There have only been occasional reports of silver toxicity in recent years, usually associated with ingested silver.  Argyria is the commonest manifestation of toxicity (Payne et al. 1992; Tomi et al. 2004), but it can also be seen as silver deposition in the liver and kidneys (Lansdown 2006).  Sensitization to silver is rarely described in the scientific literature and has a lower incidence compared to other topical antimicrobials used in personal care and wound dressings.

Silver Life Textiles and the Environment:

In the environment, silver is usually associated with sulphide minerals and released into soil and surface water through weathering.  However, in areas where silver levels are high due to industrial pollution events, toxicity to fish and marine life has been reported.  Uncontrolled release of silver into the water supply from wastewater treatment plants and accumulation in waste products may have a secondary effect on animals and plants that may have long-term effects e.g., affecting the food chain (Pelkonen et al. 2003).  This is closely monitored by environmental agencies throughout the world.

Silver Life Textiles have been tested up to 400 machine washing cycles with no removal or leaching of silver from the polyester fibres, while the pathogen prevention properties remained 99.9% secure.  The US Environmental Agency has also passed the Silver Life Textiles (Silverbac) as environmentally safe and is the only silver based textile to have received this accreditation at the time of writing.

Silver Life Textiles and Lifestyle, Fashion and Sport:

Obviously, we believe that the use of Silver Life Textiles will help reduce the risk of healthcare-associated infections.

Equally, if clothing and other fabric use contains our Silver Life Textiles and that fabric is moist, then the silver will be activated and microbes such as bacteria and fungi will be reduced with the potential to irradicate odour.

Healthy human skin is colonized by a range of bacteria including coagulase negative Staphylococci, Diphtheroids and Propionibacteria (Elsner 2006).  The distribution and density of this normal “flora” is dependent on age, sebum secretion, occlusion, temperature and humidity. Odour production is often attributed to Corynebacterium sp., and S. epidermidis found in moist areas such as the axilla, feet, arm-pits, etc.  These bacteria decompose natural secretions containing short chain fatty acids, sulphur compounds and steroids.  Malodorous volatile compounds are produced from this action, for example isovaleric acid (Taylor et al. 2003).  An individual can release these odours when excessively exercising or if washing is infrequent.

Any item of clothing or footwear will absorb the odours referred to above but most importantly the organisms will be transferred onto the clothing.  Ag+ nanoparticles have been incorporated into foot powders, sprays, soaps, socks, shoe insoles and a wide range of textiles used for pyjamas, briefs, undergarments and pillows to help reduce these malodourous events.

We plan to incorporate our Silver Life Textiles into these product lines into the future.

We hope this “Background Science” document helps and explains our enthusiasm for this technology and our product range.

Dr Alan Green, BSc, PhD, MBA

Ms Cheryl Pylypczuk, BSc, FIBMS, CSI

SP Science Limited

November 2020

 

References:

Barillo DJ and Marx DE (2014) Silver in medicine: the basic science. Burns. 2014 Dec;40 Suppl 1:S9-S18.

Chappell, J.B. and Greville, G.D. (1954) Effect of silver ions on mitochondrial adenosine triphosphatase. Nature 174, 930–931.

Dibrov, P., Dzioba, J., Gosink, K.K. and Hase, C. (2002) Chemiosmotic mechanism of antimicrobial activity of Ag+in Vibrio cholerae. Antimicrob Agents Chem 46, 2668–2670.

Elsner, P. (2006) Antimicrobials and the skin physiological and pathological flora. Curr Probl Dermatol 33, 35–41.

Galdiero, S., Falanga, A., Vitiello, M., Cantisani, M., Marra, V., & Galdiero, M Silver Nanoparticles as Potential Antiviral Agents Molecules 2011, 16, 8894-8918

Hamilton-Miller, J.M., Shah, S. and Smith, C. (1993) Silver sulphadiazine; a comprehensive in vitro reassessment. Chemotherapy 39, 405–409.

Lansdown, A.B. and Williams, A. (2004) How safe is silver in wound care? J Woundcare 13, 131–136.

Modak, S.M. and Fox, C.L. Jr (1973) Binding of silver sulfadiazine to the cellular components of Pseudomonas aeruginosa. Biochem Pharmacol 22, 2391–2404.

Nakane, T., Gomyo, H., Sasaki, I., Kimoto, Y., Hanzawa, N.,Teshima, Y. and Namba, T. (2006) New antiaxillary odour deodorant made with antimicrobial Ag-zeolite (silverexchanged zeolite). J Int Cosmet Sci 4, 299–309.

Payne, C.M., Bladin, C., Colchester, A.C., Bland, J., Lapworth, R. and Lane, D. (1992) Argyria from excessive use of topical silver sulphadiazine. Lancet 340, 126.

Rosenkranz, H.S. and Rosenkranz, S. (1972) Silver sulfadiazine: interaction with isolated deoxyribonucleic acid. Antimicrob Agents Chemother 2, 373–383.

Schreurs, W.J. and Rosenberg, H. (1982) Effect of silver ions on transport and retention of phosphate by Escherichia coli. J Bacteriol 152, 7–13.

Semeykina, A.L. and Skulachev, V.P. (1990) Sub-micromolar Ag+ increases passive Na+ permeability and inhibits respiration-supported formation of Na+ gradient in Bacillus FTU vesicles. FEBS Lett 269, 69–72.

Taylor, D., Daulby, A., Grimshaw, S., James, G., Mercer, J. and Vaziri, S. (2003) Characterization of the microflora of the human axilla. Int J Cosmet Sci 25, 137–145.

Teng, Q.L., Wu, J., Chan, G.Q., Gui, F.Z., Kim, T.M. and Kim, J.O. (2000) Mechanistic study of the antibacterial effect of silver ions on Escherichia coli and Staphylococcus aureus. J Biomed Mater Res 52, 662–668.

Tomi, N.S., Kranke, B. and Aberer, W. (2004) A silver man.Lancet 363, 532.