Polysaccharide-coated porous starch-based oral carrier for paclitaxel: Adsorption and sustained release in colon

A porous starch-based carrier coated with chitosan-phytic acid was designed for oral administration to improve drug delivery to the colon. Using hydrophobic paclitaxel as a model drug, improved drug loading (15.12% ± 0.31%) and entrapment efficiency (86.63 ± 1.30%) of porous starch were achieved by size/shape matching and adsorption force. Fluorescent paclitaxel particles inside starch were captured clearly. Furthermore, chitosan-phytic acid was added as a second protection since porous starch showed a dissolution rate of only 14.98-20.27% during the simulated digestion in stomach and small intestine, which was far lower than that of raw paclitaxel in porous starch (59.65 ± 2.57%). The release curve in the colon was also obtained and showed that 86.98 ± 2.90% of the drug was released. Finally, we verified the non-covalent interactions between starch and paclitaxel. This showed that the retention of paclitaxel into porous starch decreased once hydrogen bonding stopped. The hydrophobic CH-π effect provides a binding complementing contribution.