Synthesis and physicochemical properties of biocompatible N-carboxyethylchitosan

A novel simple method was developed to successfully synthesize biocompatible N-carboxyethylchitosan (NCECS) with a substitution degree of approx. 41% using the Michael addition reaction. The NCECS structure was characterized by Fourier transform infra-red spectrometry (FT-IR), (1)H-NMR, elemental analysis, X-ray diffraction spectrometry (XRD) and thermogravimetric analysis (TGA). The physicochemical properties of NCECS in solution are found to be strongly dependent on the pH value. In the pH range of 5.0-5.5, NCECS aggregates in dilute aqueous solution as evident by steady-state fluorescence spectroscopy and viscosimetry. The aggregated NCECS shows a spheric morphology from the atomic force microscopy (AFM) study. The possible aggregation mechanism was discussed.