Physicochemical Properties of (Ethylene Glycol)-Containing Self-Assembled Monolayers Relevant for Protein and Algal Cell Resistance

Abstract

The influence of the number of repeating units in self-assembled monolayers (SAMs) of ethylene glycol and of their end-group termination on the settlement and adhesion of two types of algal cells, viz., zoospores of the macroalga Ulva and cells of the diatom Navicula , was studied. The findings are related to the resistance of these surfaces against fibrinogen adsorption. Results showed that settlement and adhesion of algal cells to oligo(ethylene glycol) (OEG; 2-6 EG units) and poly(ethylene glycol) (PEG; MW = 2000, 5000) SAMs was low, while resistance was less effective for mono(ethylene glycol) (EG(1)OH)-terminated surfaces. These findings concur with former protein adsorption studies. In situ microscopy showed that PEG surfaces inhibited the settlement of zoospores, i.e., zoospores did not attach to the surfaces and remained motile. In contrast, on EG(2-6)OH surfaces, although zoospores settled, i.e., they secreted adhesive and lost motility, adhesion between secreted adhesive and the surface was extremely weak, and the settled spores were unable to bond to the surfaces. The influence of surface properties such as hydration, conformational degrees of freedom, and interfacial characteristics of the SAMs is discussed to understand the underlying repulsive mechanisms occurring in (ethylene glycol)-based coatings.

Settlement Behavior of Zoospores of Ulva linza During Surface Selection Studied by Digital Holographic Microscopy

“…3c. In line with previous studies, FOTS showed the highest amount of settlement after 45 min and glass (AWG) an intermediate coverage of zoospores, while the PEG coated surface had no settled spores [6,26]. These results positively correlate with the deceleration of the spores Fig.…”

Surface Sensing and Settlement Strategies of Marine Biofouling Organisms

“…The study clearly shows that receding contact angle is not the only surface property that mediates spore settlement and there exist classes of surfaces where such a correlation is not valid. A similar observation has been made by the Grunze group, who found that surfaces with similar wettability can show different settlement of zoospores [33,82]. In this study, ethylene glycols with different chain length and thus decreasing packing density were used [82,83].…”

“…Despite the different hydration, all of the tested surfaces have a similar water contact angle [82,83]. Ulva zoospore experiments show that spores adhere much weaker on well hydrated surfaces [33], an observation in line with the protein resistance of the surfaces [83]. The fact that changing hydration continuously alters the inertness of a surface was finally proven by Christophis et al [86] who used a microfluidic experiment to show that the adhesion strength of cells gradually decreases with increasing ethylene glycol chain length.…”

“…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].…”

“…Application of SAM in biofouling research was pioneered by the Lopez group [25,64]. Extensive studies followed, focusing on various surface properties including wettability, hydration, and lubricity [31,33,64,67,77,78]. Figure 6a shows a compiled viewgraph of Ulva linza zoospore settlement, Navicula perminuta settlement, and protein resistance on different aliphatic SAMs [64], methyl terminated oligosaccharide SAMs [48,65], and oligoethyleneglycol based SAMs with aliphatic termination [31].…”