Interfacial Tension Analysis of Oligo(ethylene glycol)-Terminated Self-Assembled Monolayers and Their Resistance to Bacterial Attachment

• Published in: Langmuir Vol. 28; no. 35; pp. 12844 - 12850
• Main Authors: Ista, Linnea K, López, Gabriel P
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 04.09.2012
• Subjects: Alkanes - chemistry; Bacteria; Bacterial Adhesion - drug effects; Biofouling - prevention & control; Chemistry; Colloids; Exact sciences and technology; General and physical chemistry; Gold - chemistry; Halomonadaceae - drug effects; Halomonadaceae - physiology; Polyethylene Glycols - chemistry; Polyethylene Glycols - pharmacology; Solid-liquid interface; Surface physical chemistry; Surface Tension; Thermodynamics; Water - chemistry; Water; Self assembly; Monolayer; Gold; Correlation; Fouling; Hydration; Interface tension; Force; Ethylene; Glycerol; Transition metal; Contact angle; Density; Solid; Adsorption; Packing; Surface tension; Mathematical model; Physicochemical properties; Glycol; Hydrogen bond
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la302601x

The fouling resistance of oligo(ethylene glycol) (OEG)-terminated self-assembled monolayers (SAMs) of alkanethiolates on gold has been well established. Although hydration of the OEG chains seems key to OEG-SAM resistance to macromolecular adsorption and cellular attachment, the details of how hydration prevents biofouling have been inferred largely through computational methods. Because OEG-SAMs of different lengths exhibit differing degrees of fouling resistance, the interactions between water and OEG-SAMs leading to fouling resistance can be deduced by comparing the properties of fouling and nonfouling OEG-SAMs. While all OEG-SAMs had similar water contact angles, contact angles taken with glycerol were able to individuate between different OEG-SAMs and between fouling and nonfouling OEG-SAMs. Subsequent estimation of surface and interfacial tension using a colloidal model showed that nonfouling surfaces are associated with an increased negative interfacial tension between those OEG-SAMs that resisted attachment and water. Further analysis of this interfacial tension experimentally confirmed current mathematical models that cite OEG–water hydrogen-bond formation as a driving force behind short-term fouling resistance. Finally, we found a correlation between solid–water interfacial tension and packing density and molecular density of ethylene glycol.