Bacterial cellulose-based hydrogels carrying Lewis X trisaccharides as a system for monitoring carbohydrate–carbohydrate interactions with the naked eye

Bacterial cellulose-based hydrogels carrying Lewis X trisaccharides were prepared via a three-step synthetic route, involving (1) NaIO4 oxidation of commercially available nata de coco, (2) reductive amination of the product using propargylamine, and (3) Cu+-catalysed alkyne-azide cycloaddition using azide-functionalised Lewis X trisaccharides. The resultant bacterial cellulose-based hydrogels were assembled in aqueous media containing Ca2+ or Na+, demonstrating ion-mediated interactions among Lewis X trisaccharides. Furthermore, reference experiments using bacterial cellulose-based hydrogels carrying N-acetyl-lactosaminides and those carrying N-acetyl-D-glucosaminides revealed that the two non-reducing terminals (i.e., β-galactoside and α-fucoside of Lewis X trisaccharide) substantially contribute to their interactions.