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Acticoat* Science of Silver

This information is intended for Healthcare Professionals only.



Step 1.

Understanding silver, why do we use it?
We have known about the powerful effects of silver for centuries, but why is it so good at killing bacteria? This is because silver ions (electrically charged atoms) kill microbes. They do this by blocking the pathways that allow them to breathe.


This has led to silver being used a great deal in the management of wounds, where many types of infection are often present. Silver products exist in a variety of forms and one of the most recent introductions is Nanocrystalline silver.


In order to achieve antimicrobial effect, silver needs to be in ionic form (in other words, in solution). Studies have shown that individual strains of bacteria are susceptible to silver (i.e. killed), at a range of concentrations, depending upon the type of silver species available. Ideally a silver dressing will maintain its antimicrobial efficacy for prolonged use.


Step 2.

Understanding nanocrystalline† silver & why it's different

When choosing a silver dressing, care should be taken to ensure that :-

  • Silver is available quickly to protect the wound from infection.
  • An appropriate concentration of silver is available to kill a broad range of bacteria, which may be present in the wound.
  • The silver is available for a prolonged duration, preferably for the duration that the dressing is in place.
  • The silver is not rapidly deactivated or consumed.

Nanocrystalline silver is a highly soluble form of silver that exists in tiny crystals, which are not visible to the naked eye. When coated onto the dressing material the crystals provide a large surface area, which when exposed to a wound, is greater than the same area of metallic silver. Some other forms of silver can take hours to work, which will allow time for bacteria to reproduce. Nanocrystalline silver starts to work ( in-vitro) in as little as thirty minutes and releases silver ions ( in-vitro ) at a concentration of around 70 parts per million (ppm), in water.


In traditional silver products (such as silver nitrate), most of the silver carries a strong positive electrical charge, which makes it highly soluble, but this also means that it reacts readily with substances such as the chloride from the salt in the wound, turning it into silver chloride, which makes it ineffective. As a result, dressings using these silver compounds provide a high initial release of silver ions, but most of this is then rapidly inactivated. These dressings will need to be frequently changed.


Nanocrystalline silver releases both silver ions and metallic silver. The result is the available silver does not react with chloride as quickly as ionic silver and is not inactivated so soon by the wound fluid and salts. Once the initial concentration of silver ions is used up the metallic silver then converts into silver ions. This enables the antimicrobial benefits of Nanocrystalline silver to last longer and continue to kill bacteria, whilst the dressing is in place, without needing to be applied again and again.


Maginification of silver
Magnification of nancrystalline silver Magnification of normal silver



Step 3.

Understanding Acticoat dressings
Nanocrystalline silver is the antimicrobial component in the Acticoat range of dressings. Acticoat has one layer of absorbent rayon-polyester, sandwiched between two layers of silver coated HDPE, while Acticoat 7 (a dressing made for extended use) has two sheets of absorbent material and three layers of silver coated HDPE. The silver sheets provide a microbial barrier and the absorbent core helps maintain a moist healing environment.


Acticoat does not release its silver all in one go; the silver continues to be released, providing constant levels of silver within solution. Scientists have shown that the total available silver in the Acticoat range of dressing is not matched by other silver dressings. Acticoat remains effective for up to three days, and Acticoat 7 for up to seven days. This means that the dressing remains effective over the wear time of the dressing. The dressing also provides patient comfort and added convenience.


It is important for silver dressings to be effective against a wide range of organisms and not just those, which may in-vitro be susceptible to a low dose of silver. Acticoat dressings are effective against most of the bacteria, fungi, yeasts and moulds present in infected wounds. In fact they are effective (in-vitro) against over 150 types of pathogens4 including resistant organisms such as methicillin-resistant staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE):Types of bacteria Acticoat is effective against:



Sample species
Gram-negative bacteria P.aeruginosa; P.stutzeri; Enterobacter cloacae; E coli; K pneumoniae

Gram-positive bacteria

S aureus; S epidermidis; Enterococcus faecium; Enterococcus faecalis
Antibiotic-resistant bacteria MRSA; VRE; multi-drug resistant P.aeruginosa; vancomycin-resistant Enterococcus faecium

Yeasts and moulds

Candida glabrata; Candida albicans; Candida tropicalis; Saccharomyces cerevisiae


Step 4.

Advanced dressings for everyday wounds
Although Acticoat has been shown to be very helpful in the management of complex, infected wounds, it also works to protect everyday wounds from the risk of infection, saving time and money and reducing distress to the patient.


Acticoat works rapidly. The bacteria killing effect takes place in-vitro in as little as 30 minutes. Acticoat will then continue to maintain an effective barrier for up to three days (and up to seven days with Acticoat 7) meaning that dressings don't have to be changed so often. The wound will then not have to be manipulated, which can cause trauma to new skin growth.


Inflammation is a constant feature of chronic wounds and can cause severe problems by affecting the healing process. In a number of studies MMP levels and their activity, key parameters in the wound healing process, appeared to be affected by the application of Acticoat dressings. The likely reasons for this effect is Acticoat's ability to reduce bacterial proliferation, a recognised cause of chronic inflammation in wounds. By preventing and reducing bacterial proliferation Acticoat can assist faster healing.


Step 5. Using Acticoat


View range of products and instructions for use on Product Range page.






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Nanocrystalline Silver is a patented technology of NUCRYST Pharmaceuticals Corp.
TM SILCRYST is a trademark of NUCRYST Pharmaceuticals Corp, used under licence