A novel approach to prepare tripolyphosphate/chitosan complex beads for controlled release drug delivery

A novel approach was developed to improve the mechanical strength of tripol yphosphate (TPP)/chitosan beads prepared under coagulation condition at 4 d egrees C in the presence of gelatin. Cross-sectional analysis indicated tha t the beads had a homogeneous crosslinked structure, as a result the beads were strengthened greatly (the mechanical strength increased more than ten times). Furthermore sodium alginate (a polyanion) can interact with cationi c chitosan on the surface of these TPP/chitosan beads to form polyelectroly te complex film for the improvement of the drug sustained release performan ces. The loading efficiency of model drugs (brilliant blue and FITC-dextran ) in these beads was very high (more than 90%,). Crosslinking time, TPP sol ution pH and other preparation factors had an effect on the drug release pe rformance of beads. The release period of brilliant blue (a poor water solu ble dye) was more than 2-months at a fairly constant. rate in 0.9% NaCl, 10 mM PBS pH 7.4. However, for FITC-dextran (a water soluble polysaccharide) only 1-2 days in the same conditions. It seems that TPP/chitosan bead prepa red by the novel method is a promising formulation for drug delivery. (C) 2 000 Elsevier Science B.V. All rights reserved.