Reduced protein adsorption and platelet adhesion by controlled variation of oligomaltose surfactant polymer coatings

Abstract

A series of oligomaltose surfactant polymers were prepared by the simultaneous coupling of hydrophilic maltolactone [of 2(M2), 7(M7), or 15(M15) glucose units] and hydrophobic N-(hexanoyloxy)succinimide (Hex) groups to the amino groups of a poly(vinyl amine) backbone. The surfactants were characterized by FTIR and 1H-NMR spectroscopies for purity and composition. Contact-angle and AFM measurements confirmed full monolayer adsorption for all surfactants on a model surface, highly oriented pyrolitic graphite, while full coverage was observed on polyethylene only for PVAm (M7:Hex) due to the optimal M7:Hex ratio and Hex chain density. On graphite, protein resistance increased with increasing coating thickness from 81.4 to 85.8 to 95.8% for the M2, M7, and M15 surfactants, respectively. Additionally, static platelet adhesion on all three surfactants dropped substantially to 15% (M2), 17% (M7), and 16% (M15)compared to glass (adhesion normalized to 100%) and a polyurethane (24%) surface. Protein- and platelet-resistant properties of the controlled oligomaltose layers are discussed by analysis of molecular modeling, oligomaltose and hexanoyl chain densities, and surfactant stability.

Antifouling properties of oligo(lactose)-based self-assembled monolayers

“…If the differences in total intensity of the O-H-stretching bands are translated into equal differences in the number of hydrogen-bonded water molecules, the enthalpic cost of replacing the bound water by other molecules is greater on Lac 3 than on Lac 2 or Lac 1, which could explain the observed differences in protein adsorption. This would be just as expected from a wealth of previous results, ranging from early work on PEG brushes (Jeon et al 1991) and OEG conformers (Wang et al 2000) to more recent results from protein adsorption onto oligomaltose surfactant polymers, showing positive correlation between protein resistance and the increasing depth of the oligomaltose layer (Ruegsegger and Marchant 2001). This, of course does not clarify the opposite trend observed in the U. linza spore assay.…”

“…The cell glycocalyx is rich in glycosylated molecules, and the high resistance of this hydrated structure toward nonspecific interactions is a source of inspiration for biomimetic antifouling materials. Ruegsegger and Marchant (2001) developed glycocalyx-like materials based on oligomaltose with ability to resist protein and platelet adhesion, and have been followed by others (Ham et al 2013, Sen Gupta et al 2006.…”

Poly(ethylene oxide) surfactant polymers

“…However, AFM currently lacks sufficient resolution to obtain visual confirmation of this mechanism on synthetic polymer substrates. Confirmation of the stability of surfactant polymer adhesion on synthetic polymer substrates can be obtained by testing under an applied shear stress followed by conventional surface analysis methods [12,15].…”

“…In living systems, however, adhesive and non-adhesive interactions are controlled and directed by the cell-surface-glycosylated molecules, known as glycocalyx [9]. In following this biological perspective, glycocalyx-like oligosaccharide-rich surfaces have been designed in our laboratory as a potential solution to the medical-device-related problems of thrombosis [10][11][12].…”

“…The hexanoyl chains serve to anchor the polymer surfactant to the substrate through entropic hydrophobic interactions, while the hydrophilic dextran chains orient into the aqueous environment to provide a glycocalyx-like steric barrier. The surfactant polymers are surface active at both the air/water interface, as determined by significant decreases in water surface tension; and at the solid/water interface, as determined by spontaneous adsorption onto highly oriented pyrolytic graphite (HOPG) [11] and polyethylene [12] observed by AFM. Furthermore, oligosaccharide surfactant polymers-modified surfaces showed approximately 90% reduction in non-specific adsorption of plasma proteins [11,12].…”