2.2.2 Non-specific physicochemical interactions
In non-specific physical-chemical interactions, the adhesion of bacterial appendages and proteins occurs through non-covalent interactions with specific chemical components on the surface. The interactions, in this case, are mainly van der Waals (usually attractive), electrostatic (usually repulsive), hydrophobic, or acid-base interactions (attractive or repulsive) but are influenced by the composition of the medium, the pH of the environment, pressure, nutrients, oxygen and the nature of the surface[12,27-30].
These interactions are related to the distance from the bacteria to the material surface. Usually, when the distance is greater than 50 nm, the van der Waals force plays a major role, and when the distance is shorter (10-20 nm), the van der Waals force and the electrostatic effect act simultaneously [33]. When the distance is further reduced to 1.5 nm, in addition to van der Waals and electrostatic interactions, some specific interactions may also exist.[27].