ELLIPSOMETRY STUDIES OF THE MUCOADHESION OF CELLULOSE DERIVATIVES

The mucoadhesion of three different cellulose derivatives, ethyl(hydroxyethyl)cellulose (EHEC), hydrophobically modified hydroxyethyl cellulose (h-HEC) and a cationic cellulose derivative (amino cellulose), was investigated by in situ ellipsometry. In the measurements, gastric mucin from rat was first adsorbed onto hydrophobized silica, which provided good anchorage for the mucin layer and allowed a large amount of mucin to be adsorbed. Significant mucoadhesion was obtained for all three cellulose derivatives, indicating that overall solvency effects, electrostatic interactions or hydrophobic groups may be used to obtain mucoadhesion in cellulose systems. Of the polymers used, EHEC showed the greatest adsorption tendency which may indicate that the first approach is preferable for obtaining efficient mucoadhesion. The addition of sodium dodecyl sulphate (SDS) was found to counteract the mucoadhesion of EHEC.