Soft coatings, a new antimicrobial strategy for biomaterials?

Fighting microbial biofilms on biomaterials is usually addressed by incorporating antimicrobial agents. Nevertheless, as usual in the natural life, intrinsic properties of the material surface can also be a complementary approach. They may drastically reduce the quantity of adhered microorganisms and the remaining microorganisms can be treated with classical antimicrobial agents. Mechanical properties of material surfaces recently emerged as a possible way to impact biofilm formation, but many questions have still to be elucidated so far.

We have especially investigated whether hydrogel and non-hydrogel soft and stiff films may differently impact, microbial behavior and biofilm formation. The films have been thoroughly characterized in terms of viscoelasticity, hydration and chemistry. Microbial mobility, adhered quantity and production of organelles such as pili have been specifically investigated. Surface properties, especially mechanical ones, have been thoroughly characterized. The study has been conducted with yeast (Candida albicans) and bacteria species (Escherichia coli) as models. Our results reveal that the stiffness differently impacts the amount and mobility of the adhered cells according to the nature of the film.  These softness- and hydration-dependent microbial phenomena also vary with bacteria and yeast species.

Finally, this confirms the relevance of using some soft coatings to prevent biofilm formation on a material but also clarifies the risks to get opposite effects as desired if other crucial surface properties have not been associated.