Drawing Inspiration From Nature To Develop Antifouling Surfaces

The early colonization of surfaces and subsequent biofilm formation have severe impacts in environmental, industrial, and biomedical fields. Regardless of where the biofilm forms, the dynamics of microbial adhesion may be affected by (i) the surface topography, chemistry, and physicochemistry, (ii) environmental conditions as the presence of other microorganisms and, (iii) hydrodynamics. In previous work, we have shown that the surface material is one of the parameters with the strongest impact on biofilm onset. Therefore, our interest is focused on the development of surfaces that either prevent or reduce bacterial adhesion due to an unfavorable topography or chemistry (antifouling surfaces) or contain compounds that are antibacterial and act against attached cells. Biomimetic self-cleaning and antifouling surfaces have shown to be an attractive approach for the prevention of bacterial attachment and subsequent biofilm formation since the modification of surface topography may enable the control of the contact area between the surface and the cell. This study developed a biomimetic wax surface using a moulding technique that emulated the topography of the self-cleaning Gladiolus hybridus (Gladioli) leaf. A comparison of topographies was performed for unmodified wax surfaces (control), biomimetic wax surfaces, and Gladioli leaves using Optical Profilometry and Scanning Electron Microscopy. The results demonstrated that the biomimetic wax surface and Gladioli leaf had similar surface roughness parameters, but the water contact angle of the Gladioli leaf was significantly higher than the replicated biomimetic surface. The self-cleaning properties of the biomimetic and control surfaces were compared by evaluating their propensity to repel Escherichia coli and Listeria monocytogenes attachment, adhesion, and retention in mono- and co-culture conditions. When the bacterial assays were carried out in monoculture, the biomimetic surfaces retained fewer bacteria than the control surfaces. However, when using co-cultures, the cell numbers were only reduced on the biomimetic surfaces following retention assays. These preliminary results provide valuable information into the antifouling physical and chemical control mechanisms found in plants, which are particularly appealing for engineering purposes