Glycochips from Polyanionic Glycopolymers as Tools for Detecting Shiga Toxins

Abstract

An alternating layer-by-layer adsorption methodology was applied to the assembly of glycochips by using synthetic polyanionic glycopolymers. Three glycochips carrying globobioside (Gb(2)), beta-lactoside (beta-Lac), or alpha-D-mannoside (alpha-Man) residues were prepared, and used for the detection of Shiga toxins, Stx-1 and Stx-2, by using surface plasmon resonance (SPR). Using this method, we could confirm that both Stx-1 and Stx-2 show binding specificity for the Gb(2) glycochip as well as a weak affinity for the beta-Lac glycochip. The affinity constants of these toxins depended strongly on the sugar content of the Gb(2) polymer used to prepare the glycochip. Greater affinity was observed for chips with a higher sugar content (up to 43 %) in the Gb(2) glycopolymer. The maximal affinity constants of Stx-1 and Stx-2 (K(a)=10(8)-10(9) M(-1)) enabled highly sensitive and facile analysis (10 ng mL(-1), 30 min). When Gb(2) glycopolymers were used as competitors, Stx-1 and Stx-2 behaved differently from one another in terms of their SPR response; this allowed us to perform discriminative analysis between the two toxins.