Self-assembled monolayers (SAMs) of galactoside-terminated alkanethiols have protein-resistance properties which can be tuned via the degree of methylation Langmuir 2005, 21, 2971-2980. Specifically, ...a partially methylated compound was more resistant to nonspecific protein adsorption than the hydroxylated or fully methylated counterparts. We investigate whether this also holds true for resistance to the attachment and adhesion of a range of marine species, in order to clarify to what extent resistance to protein adsorption correlates with the more complex adhesion of fouling organisms. The partially methylated galactoside-terminated SAM was further compared to a mixed monolayer of ω-substituted methyl- and hydroxyl-terminated alkanethiols with wetting properties and surface ratio of hydroxyl to methyl groups matching that of the galactoside. The settlement (initial attachment) and adhesion strength of four model marine fouling organisms were investigated, representing both micro- and macrofoulers; two bacteria (Cobetia marina and Marinobacter hydrocarbonoclasticus), barnacle cypris larvae (Balanus amphitrite), and algal zoospores (Ulva linza). The minimum in protein adsorption onto the partially methylated galactoside surface was partly reproduced in the marine fouling assays, providing some support for a relationship between protein resistance and adhesion of marine fouling organisms. The mixed alkanethiol SAM, which was matched in wettability to the partially methylated galactoside SAM, consistently showed higher settlement (initial attachment) of test organisms than the galactoside, implying that both wettability and surface chemistry are insufficient to explain differences in fouling resistance. We suggest that differences in the structure of interfacial water may explain the variation in adhesion to these SAMs.
Biofilm developed on stainless steel was characterised using biological, chemical and biochemical parameters, as well as aldose molecular biomarkers. Biofilm biomass and carbohydrate concentration ...increased on stainless steel, whereas C:N and organic carbon:chlorophyll a ratios decreased over the period of immersion. Despite the abundance of microalgal biomass, carbohydrate concentration was lower than that observed for proteins. Carbohydrate composition varied during the period of immersion. Glucose, arabinose and xylose were relatively more abundant during the initial period (5 d) of immersion, whereas rhamnose, fucose, ribose and galactose were more abundant during the latter period (>5 d) of immersion. The sugar distribution trends suggest that biofilm carbohydrates were mostly derived from degraded biogenic and/or terrestrial sources, especially during the initial period (<5 d) of immersion. As the period of immersion increased, the contribution of biogenic sources to the biofilm carbohydrates increased. This conclusion was also supported by principal component analysis based on wt % aldose composition. Multi-parameter approaches such as the one used in the present study provide a better picture of the sources and nature of biofilm organic matter.
Polymer brush coatings, consisting of polymer chains covalently attached to a surface and being less than a hundred nanometer thick, allow the creation of functional surfaces without altering the ...inherent bulk properties or appearance of a product. Surface properties depend on the type and length of the polymer used, as well as on the grafting density of the polymer brush. By making use of a polymeric primer layer that is covalently linked to the substrate and creates a uniform and highly functionalized surface, polymer brush coatings with high grafting densities can be created. In this paper we report the preparation of hydrophilic as well as hydrophobic brush coatings on different substrates through the use of a poly(acrylic acid) primer layer. In addition, hydrophilic poly(ethylene glycol) brush coatings thus produced were shown to decrease adhesion of marine bacteria.
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