Nano-chitin reinforced agarose hydrogels: Effects of nano-chitin addition and acidic gas-phase coagulation

Abstract

Hydrogels based on natural polymers such as agarose usually show low applicability due to their weak mechanical properties. In this work, we developed a dual cross-linked agarose hydrogel by adding different amounts of TEMPO-oxidized nano-chitin (0–0.2 %) to agarose hydrogel matrices and then physically cross-linked under acidic gas-phase coagulation. The prepared hydrogels were characterized by FTIR, XRD, TGA, and SEM. The effects of nano-chitin addition and acidic gas-phase coagulation on the properties of agarose hydrogels, such as gel strength, swelling degree, rheological properties, and methylene blue (MB) adsorption capacity, were also studied. Structural characterizations confirmed that nano-chitin was successfully introduced into agarose hydrogels. The gel strength, storage modulus, and MB adsorption capacity of agarose hydrogels gradually increased with the increasing nano-chitin addition, whereas the swelling degree decreased. After acidic gas-phase coagulation, agarose/nano-chitin nanocomposite hydrogels exhibited improved gel strength and storage modulus, while the swelling degree and MB adsorption capacity were slightly reduced. The combination of oxidized nano-chitin and acidic gas-phase coagulation is expected to be an effective way to improve the properties of natural polymer hydrogels.