Bacterial Adhesion to Low Energy Solid Surfaces: A Surface Thermodynamics Approach

Abstract

A desired approach to reduce bacterial adhesion to ship hull, heat exchanger and medical device surfaces is to make them less attractive for bacteria by applying anti-fouling or foul-release surface coatings. However, the selection of a useful anti-fouling coating is a difficult problem and surface thermodynamics may guide us in this respect. In this work, we investigated the independent contributions of substrate–water, γ _SW ^Tot, substrate–bacteria, γ _SB ^Tot, and bacteria–water, γ _BW ^Tot, interfacial free energies to the total free energy of adhesion, ΔG _SWB ^Tot, of Pseudomonas fluorescens bacteria on the Si- and SiN-doped DLC coated glass slide surfaces using the Lifshitz–van der Waals and acid–base surface free energy components theory. It was found that mostly acid–base interactions determine the bacterial removal properties. The repulsion between bacteria and the solid surface in water increases if γ _SB ^AB is large and γ _SW ^AB is small, when they are both positive. When Lifshitz–van der Waals and acid–base components of free energy of adhesion are considered, it was found that the effect of ΔG _SWB ^LW was very small and the main effect on bacterial removal was found to depend on the ΔG _SWB ^AB parameter and bacterial % removal increased linearly with the increase of both ΔG _SWB ^AB and ΔG _SWB ^Tot parameters for all the samples.

Keywords:

• BACTERIAL ADHESION
• SURFACE FREE ENERGY
• CONTACT ANGLE
• ACID-BASE APPROACH