Facile Fabrication of Biobased Hydrogel from Natural Resources: l-Cysteine, Itaconic Anhydride, and Chitosan

Synthesis of high-value materials from natural resources via a simple chemical route is highly desirable due to the renewability and economy of biomass. Herein, we report the facile fabrication of hydrogel from chitosan and poly(thioether amide) synthesized via alternating copolymerization of l-cysteine and itaconic anhydride. The copolymerization was investigated thoroughly by nuclear magnetic resonance, mass spectrometry, size exclusion chromatography, and Fourier transform infrared spectroscopy. These characterizations collectively verified that the alternating copolymerization of l-cysteine and itaconic anhydride was successful. Furthermore, the obtained poly(thioether amide) possesses two side carboxy groups in each repeating unit, which can be used to form hydrogel with cationic chitosan with the aid of covalent coupling. It was also found that the homogenized mixture of l-cysteine, itaconic anhydride, and chitosan could afford hydrogel in situ upon immersion in acidic water. Moreover, the hydrogel exhibited potent silver ion capturing ability, which renders the hydrogel promising for water decontamination and antibacterial application purpose.