Synthesis and Self-Assembly of Galactose-Terminated Alkanethiols and Their Ability to Resist Proteins

Abstract

The synthesis of two galactose-terminated alkanethiols with the structural formula X-OC2H5NHCO(CH2)15SH (X = 2,3,4,6-tetra-O-methyl-beta-D-Gal or beta-D-Gal) is described. Single-component and mixed self-assembled monolayers (SAMs) of the methylated and nonmethylated compounds were prepared on gold and subsequently characterized with ellipsometry, contact angle goniometry, and infrared reflection-absorption spectroscopy. Studies of the irreversible protein adsorption onto the SAMs using ex-situ ellipsometry revealed very low levels of fibrinogen and lysozyme adsorption onto mixed SAMs displaying advancing water contact angles between 24 degrees and 45 degrees and below 45 degrees , respectively. A monomethylated compound (X = 6-O-methyl-beta-D-Gal) was also synthesized and assembled on gold. This particular compound was found to possess wettability properties corresponding to the low adsorption regime of the mixed SAMs, and the results from the same set of fibrinogen and lysozyme adsorption experiments showed very low levels of protein adsorption. Our findings suggest that the protein rejecting properties rely on a fine balance between the surface energy and/or hydrogen bond donating/accepting properties of the SAM surface.

Synthesis of oligo(lactose)-based thiols and their self-assembly onto gold surfaces

“…[20][21][22] The ellipsometric thicknesses (Table 1) vary in a non-intuitive manner, since the thickness difference between 1 and 2 is smaller than that between 2 to 3 (5.2 Å and 8.9 Å, respectively), although the nominal length differences between the molecules are identical. This observation is discussed further down, in conjunction with the IRAS results.…”

“…We have earlier reported that carbohydrate-based SAMs both have proteinresistant properties comparable to those of OEGs, and that they also are highly resistant to fouling by several marine fouling species. [20][21][22] In this study we present the synthesis of three oligosaccharides 1-3 (di-, tetra-, and hexa-) ( Figure 1), all functionalized with a thiopropanoylic residue, starting from the corresponding fully protected oligosaccharides (di-, tetra-, and hexa-). [23] These thiols have successfully been used to form SAMs on gold surfaces and nanoparticles.…”

Surface Sensing and Settlement Strategies of Marine Biofouling Organisms

“…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]. The individual data sets have been rescaled so that they can directly be compared.…”

“…a Compiled data for accumulation of algae (Ulva: filled circles; Navicula: diamonds) and proteins (crosses) on three chemically different SAMs: Ulva settlement on mixed hydroxyl and methyl terminated alkylthiols (green, data kindly provided by M. Callow) [64], Ulva and Navicula settlement and protein adsorption on hexaoligoethylene glycol SAMs with different aliphatic termination (red, Schilp et al [31].) and protein adsorption and Ulva settlement on oligosaccharides with different degrees of methylation (blue, Hederos et al [48,65], data kindly provided by B. Liedberg). b Receding water contact angle of amphiphilic and non-amphiphilic surfaces along with references collected by Grozea and Walker [66] [reproduced by permission of The Royal Society of Chemistry (http://dx.doi.org/10.1039/b910899h)]…”

Enhanced Antifouling Properties of Carbohydrate Coated Poly(ether sulfone) Membranes

“…20,21 Surface coatings consisting of high molecular weight polysaccharides such as dextran have been shown to reduce protein or cell adhesion to surfaces, 22,23 while modifications with short oligosaccharides or monosaccharides have also been demonstrated to have a pronounced effect on minimizing unspecific protein adsorption and biomass accumulation. [24][25][26][27] Previous work from our group showed that Galactose-modified carbon surfaces obtained via spontaneous grafting of aryldiazonium salts display an increased resistance to Bovine Serum Albumin (BSA) adsorption, compared to bare carbon surfaces. 18 Such an effect was achieved, remarkably, via immobilization of only 1-3 ML of the monosaccharide.…”