Antimicrobial functionalities

In their labs, three of the Triple-A-COAT partners KU Leuven, Stellenbosch University and Imperial College have developed exciting new nature-inspired approaches to combat pathogens. This research will now be developed further in Triple-A-COAT to create antimicrobial, antifungal and antiviral nanocellulose based coatings.

Antibiofilm compounds

The team of Prof Hans Steenackers (KUL-MICA) at KU Leuven discovered a set of natural compounds around 10 years ago 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.

2-AI structure

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 animal, 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.

KU Leuven MICA Lab Bacterial cooperation (press edition) from Mochi Motion on Vimeo.

Antimicrobial peptides

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 mechanisms of action.

The research group of Prof Marina Rautenbach at Stellenbosch University are known around the world 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.

Incorporating AMPs into our coatings will give us the option of a broad spectrum microbiocide function, or more targeted activity, without generating antibiotic resistance.

Nanopatterning of surfaces

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, which generates 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.