Synthesis and inclusion property of α-cyclodextrin-linked alginate

The inclusion ability on alginate, a hydrogel forming polysaccharide, has been introduced by covalently linking α-cyclodextrin (α-CD). The secondary hydroxyl groups of sodium alginate were activated with cyanogen bromide and subsequently reacted with 6-amino-α-CD. The degree of substitution (DS) of the resulting α-CD linked alginate was 0.05–1.58 depending on reaction condition and the ratio of 6-amino-α-CD and alginate. Using p-nitrophenol as a model compound in UV–vis and circular dichroism spectroscopic examination, the modified polysaccharide showed an ability to form a host–guest complex. Furthermore, the α-CD linked alginate found to be provided the spherical beads by treating with a calcium chloride solution.