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The Design of Wettability of Antifouling Materials on the Basis of the Molecular Properties of Marine Fouling Bacteria

Bong-Jae Park, Travis Haines, and Nehal I. Abu-Lail. School of Chemical Engineering and Bioengineering, Washington State University, 118 Dana Hall, P.O. Box 642710, Pullman, WA 99164

Our ability to design marine antifouling materials is severely limited by the lack of molecular-scale studies on how heterogeneities of the surface properties of micro-fouling bacteria affect their design. Motivated by the lack of such studies, we aimed at optimizing the wettability of antifouling materials necessary to repel fouling bacteria from marine submerged surfaces. Our approach was based on using atomic force microscopy (AFM) to quantify the nanoscale adhesion forces between a Gram-negative fouling bacterium (Acidovorax sp.) and surfaces that vary in their wettability in 0.5 M NaCl to represent the ionic strength of marine water. To vary the wettability, we decorated gold-coated AFM cantilevers with self assembled monolayers (SAMs) of -substituted alkanethiolates that ranged from hydrophilic (OH-SAMs) to hydrophobic (CH3-SAMs). Our results clearly showed that the nanoscale adhesion forces of Acidovorax sp. to hydrophilic OH-terminated SAMs (0.491 0.245 nN, n = 709) were significantly lower than adhesion forces measured between the same bacterium and CH3-terminated SAMs (2.289 1.352 nN, n = 771) (Mann-Whitney Rank Sum Test, P<0.001). Our preliminary results suggest that antifouling materials should be designed using hydrophilic materials to repel marine bacteria. Future work will quantify adhesion forces to a range of surface wettabilities created using mixed SAMs.