Preparation and in vitro controlled release behavior of a novel pH-sensitive drug carrier for colon delivery

The synthesis of a novel complex system designed for colon-targeting drug delivery was reported. The complex was prepared by dialdehyde konjac glucomannan and adipic dihydrazides to form steady Schiff base, and crosslinking with 5-aminosalicylic acid (5-ASA) through glutaraldehyde as a cross-linking agent. The structure was characterized by Fourier transform infrared (FTIR) spectroscopy, C-13 NMR, wide angle X-ray diffraction (WAXRD) and thermogravimetric analysis. In vitro release of 5-ASA from the complex showed that the total released 5-ASA after 24 h in buffer solution at pH 1.2, 6.8, and 7.4 were 4, 59, and 21%, respectively. The release rate of 5-ASA can be controlled by tuning the pH value more effectively. The results indicated that the novel pH-sensitive complex could be potentially useful for colon-targeting drug delivery system.