Influence of surface properties of resins used as binders for coatings on the theoretical and experimental adhesion of bacteria

Abstract

Resin materials are commonly used as binders for coatings that are susceptible to contamination by biofilms that form on any coated surfaces in buildings. In this study, the surface properties of resins (epoxy, acrylic and nitrocellulose) that could influence the theoretical and experimental adhesion of bacteria (Pseudomonas aeruginosa and Staphylococcus aureus) were investigated. Surface roughness was measured by atomic force microscopy (AFM), surface wettability was evaluated using water contact angle measurements, and surface free energy was determined using the contact angle measurements of test liquids with different polarities. Bacterial adhesion was studied theoretically by surface thermodynamics and experimentally by optical microscopy technique. According to the total free energy (ΔGTot) of interactions, regardless of bacterial strain, nitrocellulose was found to be thermodynamically the most favorable for bacterial adhesion (ΔGTot more negative), followed by acrylic and then epoxy, and the theoretical adhesion trend was influenced by acid-base interactions. Compared to the minor difference in surface roughness between the different types of resins, the hydrophobicity and acid-base component of the resins were found to be the key factors influencing bacterial adhesion to resin surfaces. A good relationship was found between the thermodynamic approach and the adhesion experiments (the theoretical and experimental adhesion trend was similar). It was concluded that the thermodynamic approach could be effective in interpreting the initial adhesion behaviors between bacteria and resin surfaces. These results provide insights and tool to optimize the selection of appropriate resin materials as binders for coatings to reduce the risk of biofilm contamination on the coated surfaces in buildings.