Highlights•We synthesized chitosan-based glycopolymers having multiple β-lactosides exclusively at their C6-positions.•Our synthetic routes started from partially deacetylated chitin.•Perfect N-deacetylation/phthaloylation and the subsequent C6-selective bromination/azidation afford 6-azide-6-deoxy-N-phthaloyl-chitosan with excellent structural homogeneity.•The subsequent Cu+-catalyzed Huisgen cycloadditions using alkyne-terminated β-lactoside followed by dephthaloylations gave the chitosan-based glycopolymers.•We assessed lectin-affinities of the resultant chitosan-based glycopolymers to find their unique sigmoidal binding profiles with lectins.•We assume that aggregations of the chitosan-based glycopolymers in aqueous media are responsible for the sigmoidal bindings.Chitosan-based glycopolymers having multiple β-lactosides exclusively at their C6-positions were successfully synthesized from partially deacetylated chitin through perfect N-deacetylation/phthaloylation and C6-selective bromination/azidation to afford 6-azide-6-deoxy-N-phthaloyl-chitosan and the subsequent Cu+-catalyzed Huisgen cycloadditions using alkyne-terminated β-lactoside and/or quaternary ammonium modules followed by dephthaloylations. Lectin-affinities of the resultant chitosan-based glycopolymers were assessed through fluorescence titration assays to show their unique sigmoidal binding profiles with amplified binding constants.

2,2′-Bipyridines having two lactoside- or maltoside-appendages were prepared and then, complexed with ferrous ion to afford the corresponding tris-bipyridine ferrous complexes presenting hexavalent lactoside/maltoside clusters. Each of these complexes provided a simple dynamic combinatorial library composed of two diastereomeric stereoisomers (Δ and Λ) whose ratios depend on their relative stabilities. These tris-bipyridine ferrous complexes showed different responses from each other towards alkaline/alkaline-earth metal salts. For example, the lactoside cluster showed unique two-step binding profiles, whereas the maltoside cluster did simple Langmuir-type ones. Our referential experiments revealed that intermolecular lactoside–lactoside interactions mediated by the alkaline/alkaline-earth metal cations play essential roles in the two-step binding profiles.

The glycopolymer composed of an inulin scaffold and pendent β-lactosides was developed from commercially available inulin through sequential chemical modification processes composed of tosylation, azidation, and the subsequent Huisgen cyclocoupling with an alkyne-terminated β-lactoside. The resultant inulin-based glycopolymer has unique dual affinity towards β-galactoside and α-glucoside specific lectins which is attributable to its pendent β-lactosides and terminal α-glucoside. Its gellation property was also accessed to find that the inulin-based glycopolymer forms hydrogels whose critical gellation concentration (CGC) was lower than that required for hydrogels made from native inulin. Drug release properties of the inulin-based glycopolymer were also discussed in this paper.

We successfully synthesized inulin tosylates by treating commercially available inulin with tosyl chloride and triethylamine in N,N-dimethylacetoamide at the ambient temperature for 24 h. The subsequent SN2 reactions using sodium azide afford inulin azides that can act as useful substrates for the following Huisgen cycloaddition with alkyne-terminated β-lactoside. The resultant inulin derivative having multiple β-lactosides has excellent affinity towards a β-lactoside binding lectin (RCA120). This synthetic strategy has various advantages, such as non-fragmentation of the inulin mainchain and wide applications for various alkyne-terminated functional units. Our strategy can be, therefore, used to develop various inulin derivatives that are applicable for food and medicinal industries.

Cellulose derivatives having thymidine and/or trimethylammonium appendages exclusively at C6 positions can be prepared in a convenient manner through C6-selective bromination/azidation on cellulose to afford 6-azido-6-deoxycellulose followed by chemoselective [3 + 2] cycloadditions using Cu+ as a catalyst. These cellulose derivatives take unique sheet-like structures and function as “wrapping papers” to effectively disperse single-walled carbon nanotubes in water.