Comparison of the Fouling Release Properties of Hydrophobic Fluorinated and Hydrophilic PEGylated Block Copolymer Surfaces:  Attachment Strength of the Diatom Navicula and the Green Alga Ulva

Abstract

To understand the role of surface wettability in adhesion of cells, the attachment of two different marine algae was studied on hydrophobic and hydrophilic polymer surfaces. Adhesion of cells of the diatom Navicula and sporelings (young plants) of the green macroalga Ulva to an underwater surface is mainly by interactions between the surface and the adhesive exopolymers, which the cells secrete upon settlement and during subsequent colonization and growth. Two types of block copolymers, one with poly(ethylene glycol) side-chains and the other with liquid crystalline, fluorinated side-chains, were used to prepare the hydrophilic and hydrophobic surfaces, respectively. The formation of a liquid crystalline smectic phase in the latter inhibited molecular reorganization at the surface, which is generally an issue when a highly hydrophobic surface is in contact with water. The adhesion strength was assessed by the fraction of settled cells (Navicula) or biomass (Ulva) that detached from the surface in a water flow channel with a wall shear stress of 53 Pa. The two species exhibited opposite adhesion behavior on the same sets of surfaces. While Navicula cells released more easily from hydrophilic surfaces, Ulva sporelings showed higher removal from hydrophobic surfaces. This highlights the importance of differences in cell-surface interactions in determining the strength of adhesion of cells to substrates.

Effect of contact angle hysteresis on the removal of the sporelings of the green alga Ulva from the fouling-release coatings synthesized from polyolefin polymers

“…6. This is in agreement with the results of Gudipati et al 26 and Krishnan et al 27 where the strength of attachment of sporelings was typically lower on the hydrophobic surfaces.…”

“…This finding was also supported with the results of some recent reports. 24,26,27,47 Only a weak inverse relationship between ␥ S tot of the polyolefinic films and Ulva removal was found showing that contact angle hysteresis results are the more important parameter than the surface free energy of the films in order to correlate with the Ulva foul-release properties from these surfaces.…”

“…Krishnan et al 27 reported that high levels of CAH were positively correlated with ease of removal from coatings synthesized from polystyrene-polyisobutylene block copolymers with fluorinated side-chains. Their samples coded as poly͑dimethylsiloxane͒ ͑PDMS͒ having a CAH value of 46°Ϯ 6°r esulted in 80% Ulva sporeling removal, block copolymer sample ͑27/13͒F10H9 having a CAH value of 38°Ϯ 4°re-sulted in 45% sporeling removal, and polystyrene-blockpoly͑ethylene-ran-butylene͒-block-polystyrene ͑SEBS͒ having a CAH value of 35°Ϯ 2°resulted in 27% removal.…”

Barnacle settlement and the adhesion of protein and diatom microfouling to xerogel films with varying surface energy and water wettability

“…For diatoms, adhesion strength also appears to be sensitive to surface chemistry rather than to the mechanical properties of the coating and trends are opposite to those observed for macrofoulers including small plants of the green seaweed Ulva (eg Krishnan et al 2006). Diatoms have been found to adhere more strongly to hydrophobic silicone elastomers than to glass (Terlizzi et al 2000;Holland et al 2004;Thompson et al 2008).…”

Surface Sensing and Settlement Strategies of Marine Biofouling Organisms

“…Such inert coatings have been identified for a number of well-defined surfaces in short term, single species assays. Especially ethylene glycol (EG) x -containing coatings have been used in the biomedical area [21][22][23][24] and have recently been investigated with respect to their marine anti-fouling potential [25][26][27][28][29][30][31][32][33]. However, the degradation of the ethylene-glycol-containing chemistries makes them unsuitable for long-term antifouling applications [34,35].…”