Self-Assembled Carbohydrate Monolayers:  Formation and Surface Selective Molecular Recognition

Abstract

The formation of self-assembled monolayers (SAMs) of representative thiocarbohydrate derivatives onto a gold surface has been investigated to build an artificial carbohydrate scaffold to mimic non-bonded molecular recognition phenomena. Three types of carbohydrate SAMs were formulated from (i) 1-β-Dthioglucose (1), (ii) 1-β-D-thioglucose tetraacetate (2), and (iii) 2-mercaptoethyl R-D-mannopyranoside (3). Subsequently, each SAM was spectroscopically characterized by reflection-absorption infrared spectroscopy (RAIRS). Deprotection of the acylated carbohydrate SAM was achieved in situ, indicating that chemical transformation may be performed without disruption of the sulfursgold bond. With the mannose derivative, in which the carbohydrate moiety was separated from the gold surface by the spacer unit sOCH2CH2SH, it was possible to demonstrate that such a carbohydrate SAM was able to interact selectively with a specific carbohydrate binding protein, i.e., concanavalin A (Con A). Exposure of the mannose derived SAM to a solution of Con A led to a specific binding interaction as measured by RAIRS and surface plasmon resonance (SPR). In contrast, on exposure of the mannose SAM to the L-fucose-specific lectin tetragonolobus purpureas, no such binding was observed. These results suggest that highly ordered SAMs of specifically designed carbohydrate derivatives can be formulated to mimic natural cell surface structures and used to study selective molecular recognition interactions.

Gold Manno‐Glyconanoparticles: Multivalent Systems to Block HIV‐1 gp120 Binding to the Lectin DC‐SIGN

“…The mannose conjugate 14, functionalized with a two-carbon-atom chain, was prepared as previously reported with minor modifications. [36] The mannose glycoconjugate 15 [37] was prepared by a synthetic approach based on Fisher glycosylation. [38] For the preparation of the neoglycoconjugate 16, the peracetylated bromo-mannoside [39] was glycosylated with the spacer 17 a [40] in the presence of Hg(CN) 2 as a promoter [41] to give the thioacetyl neoglycoconjugate, which was deacetylated by methanolysis [42] to yield compound 16 (see the Supporting Information).…”

Sensor Functionalities in Self-Assembled Monolayers

“…[79] The specificity of the interactions were demonstrated by the binding of concavalin A, while a fructose-specific protein did not bind to the layer. Willner and co-workers have studied the interaction between a photoisomerizable monolayer of dinitrospiropyran and anti-dinitrophenyl antibody.…”

Carbohydrate Arrays as Tools for Glycomics

“…[19] Subsequently, several SAMs were formed using thioglucose monosaccharides. [20] Characterization by reflection absorption infrared spectroscopy (RAIRS) [21] indicated that the orientation of the carbohydrates in each SAM was dependent on the anomeric thiol moiety. Thus, the nonreducing end of mannose was appropriately displayed to allow the lectins access to each monosaccharide unit.…”