Organic Fouling on Zwitterionic Amphiphilic Copolymers: Implications in Biofouling

Abstract

Zwitterionic amphiphilic copolymers (ZACs) have shown promise in resisting the attachment of oil emulsions, proteins, and organic biomolecules, suggesting their potential to prevent microbial adhesion as well. However, there is a lack of comprehensive studies exploring the role of ZACs in regulating cell deposition and subsequent biofilm formation on surfaces. Here, we fabricated ZAC coatings including poly(trifluoroethyl methacrylate-random-sulfobetaine methacrylate) (PTFEMA-r-SBMA or PT:SBMA), poly(trifluoroethyl methacrylate-random-2-methacryloyloxyethyl phosphorylcholine) (PTFEMA-r-MPC or PT:MPC), poly(methyl methacrylate-random-sulfobetaine methacrylate) (PMMA-r-SBMA or PM:SBMA), and poly(methyl methacrylate-random-2-methacryloyloxyethyl phosphorylcholine) (PMMA-r-MPC or PM:MPC). These coatings were assessed for their resistance to conditioning with organic molecules, attachment of Gram-positive, Bacillus subtilis TR11 (B. subtilis), and Gram-negative, Escherichia coli K12 (E. coli), bacteria, and subsequent biofilm formation. Surface characterizations highlighted the role of organic molecule conditioning from the media in altering the ZAC-coated surface properties, subsequently influencing bacterial deposition and biofilm growth. Cell deposition results revealed that all ZAC coatings displayed higher resistance to B. subtilis attachment compared to E. coli, indicating that bacterial adhesion to the surfaces depends on the type of bacteria. Among the tested ZAC coatings, PT: SBMA demonstrated the highest potential for resisting adhesion by both types of bacterial cells as well as exhibiting lower surface energy and lower roughness after organic medium conditioning. These findings contribute to enhancing our fundamental understanding of how zwitterionic materials control biofouling.

Keywords: Bacillus subtilis TR11; Escherichia coli K12; biofouling; coatings; zwitterionic amphiphilic copolymers (ZACs).