Physicochemical Comparison between Glass Surface and Zinc Oxide Surface: Study of Microbial Adhesion

Abstract

The general context of this work is to study the effect of physicochemical properties on bacterial adhesion. In this case, the
adhesion of Staphylococcus aureus (gram-positive bacteria) has been studied on a thin layer of zinc oxide (ZnO). This layer was
deposited on glass substrates by sputtering under different powers (150, 200 and 250 watts). The contact angle measurements
were used to calculate the surface energy components of each substrate (dispersive and polar) and to define the hydrophilic/hydrophobic character by the calculation of the free energy of interaction. Analysis of adherent cells on the surface of
each substrate was made by the atomic force microscope according to the time of suspension. The results showed that the glass
surface has a large polar component; against the surface of the ZnO film has a significant dispersive component. This shows that
the glass surface is governed by short-range forces (Lewis acid–bases forces) while ZnO film is governed by long-range forces
(van der Waals forces). Images obtained by atomic force microscopy revealed that the ZnO layer has an antibacterial effect
against S. aureus.