Self-assembly, rheological properties and antioxidant activities of chitosan grafted with tryptophan and phenylalanine

In this study, aromatic amino acid-conjugated chitosan are designed and developed, as viewed by multi-spectral methods. The results from 1H NMR, FTIR, and UV–vis indicated the successful grafting of tryptophan (Trp) or phenylalanine (Phe) onto chitosan (CS) to form Trp-CS and Phe-CS nano-conjugates with 4.7 % and 6.8 % grafting ratio. The grafting induced some influences on the chiral structure and the symmetry and backbone structure of CS. The thermal stability of Trp-CS and Phe-CS nano-conjugates is less than that of CS. Trp-CS and Phe-CS conjugates were formed as spherical nanoparticles. The rheological studies show that Trp-CS and Phe-CS exhibit characteristic of an elastic material. In addition, Trp-CS and Phe-CS present well antioxidant activities and good biocompatibility.