Conditioning of self-assembled monolayers at two static immersion test sites along the east coast of Florida and its effect on early fouling development

Abstract

Among the first events after immersion of surfaces in the ocean is surface 'conditioning'. Here, the accumulation and composition of the conditioning films formed after immersion in the ocean are analyzed. In order to account for different surface chemistries, five self-assembled monolayers that differ in resistance to microfouling and wettability were used. Water samples from two static immersion test sites along the east coast of Florida were collected at two different times of the year and used for experiments. Spectral ellipsometry revealed that conditioning films were formed within the first 24 h and contact angle goniometry showed that these films changed the wettability and rendered hydrophobic surfaces more hydrophilic and vice versa. Infrared reflection adsorption spectroscopy showed that the composition of the conditioning film depended on both the wettability and immersion site. Laboratory and field assays showed that the presence of a conditioning film did not markedly influence settlement of microorganisms.

Charged hydrophilic polymer brushes and their relevance for understanding marine biofouling

“…All samples were fully covered by biofouling (weeds and to a lesser extent microfouling) after eight weeks' immersion, and they did not differ significantly between each other (ANOVA, p > 0.05), possibly due to chemical or mechanical instability of the samples under the influence of temperature, water currents and salinity. It is also important to note that surfaces are rapidly (hours) 'conditioned' by adsorption of macromolecules on immersion, a process that may change the surface properties (Thome et al 2014). Furthermore, the adhesion and settlement of organisms in marine environments is a dynamic and complex process since many parameters influence the pattern of adhesion and settlement (Hellio & Yebra 2009), and which is also dependent on local variations in fouling pressure.…”

Compositional fingerprint of soy sauces via hydrophobic surface interaction

“…While taking the samples through the air/water interface, they were gently rinsed with MilliQ water to prevent the formation of Langmuir layers. The adsorption of soy sauce components (soy protein and glutamic acid) on DDT surfaces followed previously published protocols (Thome et al, 2014). Therefore, the hydrophobic samples were immersed into PBS buffer (pH 7.4) for 20 min before adding an equal volume of 20 mg/ml of the compound of interest in PBS buffer to obtain a final concentration of 10 mg/ml.…”

“…DDT (1-Dodecanthiol) monolayers were prepared from a 1 mM solution in ethanol p.a., following previously published protocols (Thome et al, 2014). The substrates were cleaned under UV light for 90 min, ultrasonicated in ethanol p.a.…”

“…Adsorption of the soy sauces on DDT surfaces were carried out similar to previously published protocols for protein adsorption and surface conditioning experiments (Thome et al, 2014). For each soy sauce brand, surfaces of the hydrophobic samples were immersed in the pure sauce for 20 min on a shaking table.…”

“…Protein adsorption assays are frequently used to characterize resistant properties of interfaces and hydrophobic monolayers are generally preferred as a non-protein resistant reference (Prime & Whitesides, 1991). In turn, unspecific adsorption after immersion into a complex medium reveals components that strongly interact with hydrophobic interfaces (Thome et al, 2014). The aim of this work is to introduce a pull-down assay which uses different surface characterization methods, such as spectral ellipsometry, water contact angle goniometry, ATR-FTIR spectroscopy, and X-ray reflectometry to distinguish between different compounds in soy sauces.…”