Synthesis, characterization, and evaluation of antifungal and antioxidant properties of cationic chitosan derivative via azide-alkyne click reaction.

In this work, quaternary ammonium group was introduced into chitosan backbone by cuprous-catalyzed azide-alkyne cycloaddition (CuAAC) to synthesize the cationic chitosan derivative bearing 1,2,3-triazole. The products were identified structurally by FTIR, H NMR spectroscopy, XRD, and elemental analysis. The water solubility of chitosan derivatives at different pH values was determined by a turbidity measurement. The antifungal properties of cationic chitosan derivatives against Botryis cinerea, Phomopsis asparagi, Fusarium oxysporum f. sp. niveum, and Fusarium oxysporum f. sp. cucumerium were evaluated using the radial growth assay. Besides, the antioxidant activities of them were also tested by superoxide-radical scavenging and reducing power assays. Compared to chitosan, cationic chitosan derivative bearing 1,2,3-triazole showed the good water solubility especially at alkaline condition, excellent antifungal action with over 70% inhibitory indices against tested fungi at 1.0 mg/mL, and enhanced antioxidant activity with complete scavenging efficiency against superoxide-radical at 1.6 mg/mL because of the introduction of 1,2,3-triazole and quaternary ammonium moieties. These excellent biological properties present a promising prospect for this chitosan derivative in antifungal and antioxidant biomaterials.