Chitosan Grafted with Vanillin: Its Antioxidant and Antibacterial Activity and Application in Papermaking

Chitosans were grafted with vanillin( VA) by using laccase as catalyst. The linear potentiometric titration and Fourier-transform infrared spectroscopy( FT-IR) were used to characterize the graft ratio and structural changes in the VA-chitosan,and its antioxidant and antibacterial activity were analyzed. The results showed that the graft ratio of VA-chitosan was 10. 2%. The FT-IR presented an absorption decrease of amino groups and a new band appeared at 1637 cm- 1corresponding to the CN vibrations that was characteristic of imines due to Schiff base formed between the amino groups of chitosan and the Phenolic hydroxyl of Vanillin. The IC50was 1. 62 mg / mL for ABTS·+scavenging of VA-chitosan,the measurement of reducing power showed that the absorbance at 700 nm was raised 0. 321 compared to chitosan at the concentration of 5 mg / mL,thus the results suggested that the antioxidant activity of VA-chitosan was improved. The antibacterial activities of VA-chitosan against E. coli,S. enterica,Bacillus subtilis and Staphylococcus aureus were improved compared with the original chitosan. Antimicrobial paper was prepared using VA-chitosan by the methods of surfacing coating and addition into the pulp,the antimicrobial activity and physical properties of the prepared paper were improved.