Carbohydrate-appended curdlans as a new family of glycoclusters with binding properties both for a polynucleotide and lectins

β-1,3-Glucans having carbohydrate-appendages (α-d-mannoside, N-acetyl-β-d-glucosaminide and β-lactoside) at the C6-position of every repeating unit can be readily prepared from curdlan (a linear β-1,3-glucan) through regioselective bromination/azidation to afford 6-azido-6-deoxycurdlan followed by chemo-selective Cu(i)-catalyzed [3 + 2]-cycloaddition with various carbohydrate modules having a terminal alkyne. The resultant carbohydrate-appended curdlans can interact with polycytosine to form stable macromolecular complexes consistent with two polysaccharide strands and one polycytosine strand. Furthermore, these macromolecular complexes show strong and specific affinity toward carbohydrate-binding proteins (lectins). Therefore, one can utilize these carbohydrate-appended curdlans as a new family of glycoclusters.