Measuring Surface Hydrophobicity as Compared to Measuring a Hydrophobic Effect on Adhesion Events

Simple contact-angle methods are commonly used to describe surface influences on phenomena including adsorption, adhesion, fouling, and cleaning, However, for the purpose of quantitatively relating surface hydrophobicity to such phenomena, contact-angle analysis may be insufficient. Here we show that even with model hydrophobic and hydrophilic surfaces, measurement of the effect of surface hydrophobicity on adsorption of the antimicrobial proteins nisin and bacteriophage T4 lysozyme yielded conflicting results, apparently because different mechanisms govern events at the interface, depending on surface hydrophobicity. This finding is explained in terms of the presence of two competing mechanisms for attractive associations at these surfaces: hydrophobic and attractive electrostatic associations.