In-situ characterization of self-assembled monolayers of water-soluble oligo(ethylene oxide) compounds.

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TitleIn-situ characterization of self-assembled monolayers of water-soluble oligo(ethylene oxide) compounds.
Publication TypeJournal Article
Year of Publication2011
AuthorsWalker, ML, Vanderah, DJ, Rubinson, KA
JournalColloids Surf B Biointerfaces
Volume82
Issue2
Pagination450-5
Date Published2011 Feb 1
ISSN1873-4367
KeywordsAdsorption, Animals, Cattle, Disulfides, Ethylene Oxide, Kinetics, Materials Testing, Models, Chemical, Proteins, Serum Albumin, Bovine, Sulfhydryl Compounds, Surface Properties, Time Factors, Water
Abstract

In-situ spectroscopic ellipsometry (SE) was utilized to examine the formation of the self-assembled monolayers (SAMs) of the water-soluble oligo(ethylene oxide) [OEO] disulfide [S(CH(2)CH(2)O)(6)CH(3)](2) {[S(EO)(6)](2)} and two analogous thiols - HS(CH(2)CH(2)O)(6)CH(3) {(EO)(6)} and HS(CH(2))(3)O(CH(2)CH(2)O)(5)CH(3) {C(3)(EO)(5)} - on Au from aqueous solutions. Kinetic data for all compounds follow simple Langmuirian models with the disulfide reaching a self-limiting final state (d=1.2nm) more rapidly than the full coverage final states of the thiol analogs (d=2.0nm). The in-situ ellipsometric thicknesses of all compounds were found to be nearly identical to earlier ex-situ ellipsometric measurements suggesting similar surface coverages and structural models in air and under water. Exposure to bovine serum albumin (BSA) shows the self-limiting (d=1.2nm) [S(EO)(6)](2) SAMs to be the most highly protein resistant surfaces relative to bare Au and completely-formed SAMs of the two analogous thiols and octadecanethiol (ODT). When challenged with up to near physiological levels of BSA (2.5mg/mL), protein adsorption on the final state [S(EO)(6)](2) SAM was only 3% of that which adsorbed to the bare Au and ODT SAMs.

DOI10.1016/j.colsurfb.2010.09.029
Alternate JournalColloids Surf B Biointerfaces
PubMed ID21041070