Effect of chemical modification on the solubility and swelling of microspheres based on carboxymethyl cashew gum and chitosan

Abstract

Chitosan/carboxymethylated cashew gum beads were produced via polyelectrolytic complexation. The beads were chemically modified to achieve stable acidic medium and to provide a swelling response in different pH. The beads were modified by chitosan reacetylation and by crosslinking with epichlorohydrin, glutaraldehyde and genipin. The beads were characterized by techniques such as: infrared spectroscopy, thermogravimetry, scanning electron microscopy and regarding their solubility at pH 1.2 and swelling. The beads of carboxymethyl cashew gum and reacetylated chitosan and those crosslinked with epichlorohydrin had low resistances to dissolution at pH 1.2. However, the beads crosslinked with glutaraldehyde and genipin showed resistance to dissolution along with low diffusion coefficients. Moreover, beads crosslinked with genipin presented a higher degree of swelling than beads crosslinked with glutaraldehyde at concentrations of 3% and 5% (weight/volume). Beads crosslinked with genipin presented responsive behavior to pH variation and stability at pH 1.2, indicating that these systems have potential for use in controlled drug delivery systems for oral administration.

Keywords:
cashew gum; carboxymethylation; chitosan; crosslinking