Multivalency by self-assembly: binding of concanavalin A to metallosupramolecular architectures decorated with multiple carbohydrate groups.

Abstract

Multiplication of functional units through self-assembly is a powerful way to new properties and functions. In particular, self-organization of components decorated with recognition groups leads to multivalent entities, amenable to strong and selective binding with multivalent targets, such as protein receptors. Here we describe an efficient, supramolecular, one-pot valency multiplication process proceeding through self-organization of monovalent components into well-defined, grid-shaped [2×2] tetranuclear complexes bearing eight sugar residues for multivalent interaction with the tetrameric lectin, concanavalin A (Con A). The grids are stable in water under physiological pH at a relatively high concentration, but dissociate readily at slightly more acidic pH or upon dilution below a certain threshold, in a type of on-off behavior. The carbohydrate-decorated grids interact strongly and selectively with Con A forming triply supramolecular bio-hybrid polymeric networks, which lead to a highly specific phase-separation and quasi-quantitative precipitation of Con A out of solution. Dramatic effects of valency number on agglutination properties were demonstrated by comparison of grids with divalent carbohydrates of covalent and non-covalent (L-shaped, mononuclear zinc complex) scaffolds. The results presented here provide prototypical illustration of the power of multivalency generation by self-assembly leading to defined arrays of functional groups and binding patterns.