Effect of Substratum Surface Chemistry and Surface Energy on

Two series of self-assembled monolayers (SAMs) of -substituted alkanethiolates on gold were used to systematically examine the effects of varying substratum surface chemistry and energy on the attachment of two model organisms of interest to the study of marine biofouling, the bacterium Cobetia marina (formerly Halomonas marina) and zoospores of the alga Ulva linza (formerly Enteromorpha linza). SAMs were formed on gold-coated glass slides from solutions containing mixtures of methyl- and carboxylic acid-terminated alkane-thiols and mixtures of methyl- and hydroxyl-terminated alkanethiols. C. marina attached in increasing num-bers to SAMs with decreasing advancing water contact angles (AW), in accordance with equation-of-state models of colloidal attachment. Previous studies of Ulva zoospore attachment to a series of mixed methyl- and hydroxyl-terminated SAMs showed a similar correlation between substratum AW and zoospore attachment. When the hydrophilic component of the SAMs was changed to carboxylate, however, the profile of attachment of Ulva was significantly different, suggesting that a more complex model of interfacial energetics is required. Upon submersion in a nonsterile aqueous liquid, most sur-faces become rapidly colonized by collections of bacteria and other microorganisms. These attached cells, along with extra-cellular material they produce and other organic compound