Adsorption of indomethacin onto chemically modified chitosan beads

Macroporous chitosan beads used for the immobilization of an anti-inflammat ory drug were prepared by the wet phase-inversion method. There are two sta ges of phase-inversion observed from the cast of chitosan droplet in tripol yphosphate (TPP) aqueous solution. The first stage of phase-inversion is do minated by liquid-liquid demixing and the morphology of the freeze-dried ch itosan bead shows a bundle-like porous structure. The following stage of ph ase-inversion is attributed to the solid-liquid demixing and the morphology of the freeze-dried chitosan bead changes to an interconnected porous stru cture comprising particulates around the pores. The pore size and porosity of the bead can be varied by altering synthesis conditions, such as initial polymer concentration, and the pH value and concentration of the casting a gent TPP aqueous solution). Quaternary ammonium, and aliphatic and aromatic acyl groups were introduced into the porous chitosan beads to interact wit h an anti-inflammatory drug, indomethacin, through the electrostatic intera ction and hydrophobic interaction. The results indicated that chemical modi fication of the porous chitosan beads have obvious effect on the adsorption of indomethacin. (C) 2001 Published by Elsevier Science Ltd.