ABSTRACT
Amphiphilic coatings are promising candidates for fouling-release applications. As hydrophilic components, polysaccharides are interesting and environmentally benign building blocks. We used covalently coupled alginic acid (AA) and hyaluronic acid (HA) and postmodified them with a hydrophobic fluorinated amine. The surfaces showed good stability under marine conditions and fluorination led to a decreased uptake of Ca(2+) ions after modification. In single species settlement assays (bacteria, diatoms, barnacle cypris larvae), the modification decreased the settlement density and/or the adhesion strength of many of the tested species. Field studies supported findings of the laboratory experiments, as hydrophobic modification of AA and HA decreased diatom colonization.
Subject(s)
Aquatic Organisms/physiology , Biofilms/drug effects , Biofouling/prevention & control , Surface-Active Agents/chemistry , Alginates/chemistry , Amines/chemistry , Animals , Aquatic Organisms/drug effects , Calcium/chemistry , Crustacea/drug effects , Crustacea/physiology , Diatoms/drug effects , Diatoms/physiology , Gammaproteobacteria/drug effects , Gammaproteobacteria/physiology , Glucuronic Acid/chemistry , Hexuronic Acids/chemistry , Hyaluronic Acid/chemistry , Hydrophobic and Hydrophilic Interactions , Surface-Active Agents/pharmacologyABSTRACT
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.
Subject(s)
Aquatic Organisms/physiology , Biofilms/growth & development , Biofouling , Seawater/chemistry , Florida , Hydrophobic and Hydrophilic Interactions , Spectrophotometry, Infrared , Surface Properties , WettabilityABSTRACT
For both, environmental and medical applications, the quantification of bacterial adhesion is of major importance to understand and support the development of new materials. For marine applications, the demand is driven by the quest for improved fouling-release coatings. To determine the attachment strength of bacteria to coatings, a microfluidic adhesion assay has been developed which allows probing at which critical wall shear stress bacteria are removed from the surface. Besides the experimental setup and the optimization of the assay, we measured adhesion of the marine bacterium Cobetia marina on a series of differently terminated self-assembled monolayers. The results showed that the adhesion strength of C. marina changes with surface chemistry. The difference in critical shear stress needed to remove bacteria can vary by more than one order of magnitude if a hydrophobic material is compared to an inert chemistry such as polyethylene glycol.
