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In their labs, three of the Triple-A-COAT partners KU Leuven, Stellenbosch University and Imperial College have developed exciting new approaches to combat pathogens. This research will now be developed further in Triple-A-COAT to create antimicrobial, antifungal and antiviral nanocellulose based coatings.
Around 10 years ago, the team of Prof Hans Steenackers (KUL-MICA) at KU Leuven discovered a set of natural compounds that have novel antimicrobial activity. The chemical structures are based on 5-aryl-2-aminoimidazoles (2-AIs for short), which are naturally produced by various marine sponges as anti-fouling molecules.
The compounds have been shown to be active against pathogenic bacteria (Salmonella, Staphylococci, E. coli, …) and fungi (Candida albicans). The activity can be tuned by chemical modification of the compounds to be broad-spectrum, or more targeted.
Research on these compounds at KU Leuven has shown that they are non-toxic to humans, plants and animals, and their antimicrobial activity mainly works through interfering with the production of the slimy biofilm matrix by bacteria. Bacteria are unlikely to develop resistance to this compound (see video) and this theory has been proven in salmonella bacteria. The 2-AI compounds also have some anti-adhesion functionality.
Antimicrobial peptides (AMPs) are a very common group of antibiotics produced naturally by living organisms. Tyrocidines, a class of small cyclic AMPs isolated from soil bacteria were among the first antibiotics introduced in 1939, and are now being revisited as novel antimicrobial compounds. Even though they work by killing microorganisms, very little resistance development has been observed, probably due to multiple rapid mechanisms of action.
The research group of Prof Marina Rautenbach at Stellenbosch University are well-known for their work on antimicrobial peptides. They have developed a way to easily produce tyrocidine complex in a bacteria by fermentation, and in this way produce various new AMP structures which have even stronger antimicrobial effects. They also found that the tyrocidines also tend to stick tightly to many different materials forming a potent antimicrobial coating.
Incorporating these AMPs into our coatings in Triple-A-COAT will give us the option of a broad spectrum microbiocide function, or more targeted activity, with a very low potential to generate antibiotic resistance.
There are many examples in nature of patterns, visible at the nanoscale the surface of various plants, as well as insect wings and shark skin, that are known to inhibit microbial adhesion and growth. The research group of Prof Joao Cabral at Imperial College is working on a new strategy to mimic these natural antimicrobial surfaces in synthetic and natural polymer films.
Their innovative approach uses physical wave patterns to cause a spontaneous buckling or wrinkling of the surface, and generate a uniform pattern of ridges or other structures. The eventual production process should be much cheaper than existing nanopatterning methods, for example nanoimprint lithography. Results in the lab already show that these patterns can inhibit the growth of bacteria.