Countless lives have been prolonged and improved with medical implants like pacemakers and replacement hips. But such operations also carry the risk that infection-causing microbes may grow on the implant and the immune system may reject the foreign object.

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Despite having several layers, the new biofilm is only a few hundred nanometers thick and invisible to the naked eye.
Image credit: Inserm/E. Falette

Now, an Inserm team from Strasbourg University in France has succeeded in creating a biofilm that protects against such infection.

The biomaterials and bioengineering researchers describe their work in the journal Advanced Healthcare Materials.

Inserm (Institut national de la santé et de la recherche médicale) is a national biomedical and public health research institution that is mostly based in French hospitals and universities.

The extremely thin, silver-coated biofilm has antimicrobial, antifungal and anti-inflammatory properties and can be used to cover titanium implants – including new hips, prostheses and pacemakers, and other medical devices that can cause infection, such as catheters.

The team has performed various tests on the new film and found it reduces inflammation and prevents the most common bacterial and fungal infections.

They showed that when an implant coated with the film comes into contact with human blood, the film prevents immune cells from triggering inflammatory markers.

Senior author Dr. Philippe Lavalle, research director at Inserm, says they also found that “the film inhibits the growth and long-term proliferation of staphylococcal bacteria (Staphylococcus aureus), yeast strains (Candida albicans) or fungi (Aspegillus fumigatus) that frequently cause implant-related infection.”

The team expects the film will be available for use in a few years.

Implantable medical devices provide an ideal surface for microbial colonies. This can lead to infection and inflammation and rejection of the implant.

Currently, antibiotics are used to reduce the risk of such infections, but the growth of drug-resistant microbes is making them less effective.

Despite having several layers, the new biofilm is only a few hundred nanometers thick and invisible to the naked eye. It comprises two substances: polyarginine and hyaluronic acid.

The polyarginine causes the immune system to suppress its anti-inflammatory response, and the hyaluronic acid, which occurs naturally in the body and is compatible with it, inhibits bacterial growth.

The film is also embedded with natural antimicrobial peptides, including catestatin. These are not only very effective against microbes – they kill them by punching holes in their cell walls and blocking any counter-moves – they are nontoxic to the body.

Another important feature of the biofilm is its silver lining. This prolongs its antimicrobial activity, as Dr. Lavalle explains:

Silver is an anti-infectious material currently used on catheters and dressings. This strategy allows us to extend antimicrobial activity in the long term.”

In a recent Spotlight article, Medical News Today spoke to a scientist whose team is devising nanosensors to detect infection on implants before symptoms arise. The team has already tested the technology on titanium hip implants and catheters.