Building Materials That Kill Bacteria

By Ken Collins 23/08/2010 5

In an effort to control the spread of bacteria (that are harmful to humans), the science world is always coming up with some interesting innovations. This now includes additives to building materials that will kill bacteria, including the dreaded MRSA strain.

Antimicrobial, antibacterial and antifungal powdercoating has been available commercially for a few years, and now scientists have developed an additive for paint that targets only staph bacteria.

The innovation comes in how these materials can provide lasting protection, despite some surfaces like door handles and handrails getting a lot of human interaction.

In the case of the powdercoating, the manufacturers have added silver ions to the powder coating material and found a way to keep the ions distributed through the coating once it is applied and heat fused onto the (typically metal) substrate. Powdercoating is often used as the aesthetic and protective coating on metals, such as handrails, door handles, window and door frames, furniture frames, equipment frames, etc.

Silver in various forms and silver ions have long been known to act as a natural antibiotic, dating back centuries, although it has fallen in and out of favour over time as medical knowledge has changed. The silver ions interrupt the replication ability of proteins within the bacteria, making them inactive. Having done testing for effectiveness and gaining US FDA and EPA approvals for food contact, the company that makes this powdercoating is now promoting it for use where ever you want to stop the possible spread of bacteria.

The paint additive, was discussed here and is reported to kill MRSA without the use of antibiotics. Using carbon nanotubes bound with lysostaphin, it is the lysostaphin that does the damage.nn-2010-00932t_0006

The report identifies that lysostaphin is a naturally occurring enzyme used by non-pathogenic strains of Staph bacteria to defend against Staphylococcus aureus, including MRSA. Lysostaphin works by first attaching itself to the bacterial cell wall and then slicing open the cell wall. That means it’s a highly-targeted substance – in fact, it only destroys staph bacteria.

This looks to work well in the lab, but it has yet to be turned into a commercially available product.

Although we have had fungicidal paint for some time, and it is sometimes used in high humidity areas, the concept of using building materials, or in this case entire wall surfaces, to act as an anti bacterial agent is certainly an interesting development.  On the face of it the advantages could be many, especially if it means that the building environment is helping to reduce the number of places harmful bacteria can sit and be transferred from person to person.

However, a concern that has been expressed is the evolutionary process, where we have already seen bacteria become resistant to some commonly used antibiotics. If these products are widely used, will bacteria evolve to become resistant to the active parts of these building products? Only time will tell.

5 Responses to “Building Materials That Kill Bacteria”

  • Is there a possible risk, in that not all bacteria are harmful and the anti bacterial agent does not know which ones are harmful and which are not?

  • The following extract is worthy of consideration as to the impact of nanosilver and its adverse effect on aquatic organisms;
    Dr. Samuel Luoma has given us an excellent description and analysis of the science of silver and nanosilver. His paper raises many questions for policy makers. Its subtitle, “Old Problems or New Challenges,” is appropriate, because the subject of the paper is both. Metals are among the oldest of environmental problems. Lead, silver and mercury have posed health hazards for thousands of years, and they are as persistent in the environmental policy world as they are in the
    environment. Nanotechnology is a new challenge, but the scope of the policy issues it presents is as broad and difficult as the technology itself.As the paper makes clear, there is much we do not know about the environmental pathways
    of nanosilver, its environmental effects and its impact on human health. However, as Luoma notes, ionic silver, a form of nanosilver, when tested in the laboratory, is one of the most toxic metals to aquatic organisms.

    • Having looked further at the source of the extract you refer to, the concern it raises is that nano size silver particles are being used in all manner of products. This includes everything from mouth wash to baby teethers, to household cleaners, to clothing, to the inside of fridges and washing machines, to health suppliments that are either sprayed on or ingested. Quite rightly there are concerns as to where these silver particles will accumulate and how they will affect the environment, most especially where the silver nano particles are ‘free’ to be dispersed into the environment. The report identifies that a third of products that used silver in 2007 had the potential to do this.

      However, silver that is contained (or retained) in a product does not yet appear to be so much of a concern. There is an obvious difference between silver ions that have been used on medical equipment, or in the case of powdercoating on door handles (as an example) as opposed to its use in mouth wash and household cleaners where the product is being flushed down the sink and eventually back into the environment.

      The report summary also says that “There are no examples of adverse effects from nanosilver technologies occurring in the environment at the present. But environmental surveillance is a critical requirement for a future risk management strategy, because silver nanoproducts are rapidly proliferating through the consumer marketplace……”

  • I actually work in this field, we are developing antimicrobial plastics/surfaces/paints. I perform the microbiology and toxicology testing. Nanosilver is certainly a problem because the materials rely on the fact that silver ions will leach out of the material and kill bacteria. Of course they leach out into the environment as well, which is a major concern. We dont use nanosilver for this reason.

    Nanosilver has also been implicated in causing genetic damage, see “Cytotoxicity and genotoxicity of nano-silver in mammalian cell lines” (I dont know if it is free-access). The consumption of large amount of silver-based products also causes Argyria. The silver accumulates in the skin which turns it a blue/silver colour. These sort of problems have formed the new(ish) research feild, nanotoxicology.

    There certainly needs to be better regulation of these materials as you have stated earlier, not much is yet known about their effect on the environment.

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