Synthesis, characterization, and microsphere formation of galactosylated chitosan

Chitosan derivative with galactose groups, which was recognized specifically by the asialoglycoprotein receptor (ASGR), was synthesized by introduction of the galactose group into the amino group of chitosan. The chemical structure of galactosylated chitosan was characterized by FT-IR, 1H-NMR, 13C-NMR, WAXD, and DSC techniques. The results indicated that although acyl reaction on the part of amino groups of chitosan took place, the degree of galactosylated substitution was 20%, and the crystallization, solubility, stability, and other physical properties were different from chitosan. Microspheres of chitosan and galactosylated chitosan were prepared by the physical precipitation and coacervation method with sodium sulfate, respectively. The characterizations of microspheres were determined by means of scanning electron microscopy (SEM), particle size/ζ potential analysis, and DSC methods. Spherical, positively charged chitosan and galactosylated chitosan microspheres were formed, with an average diameter of 0.54 and 1.05 μm, and average ζ potential of +17 mV and +15 mV, respectively. The novel galactosylated chitosan microspheres may be used as a potential drug delivery system with passive and active hepatic targeting properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 659–665, 2004