Preparation of Multifunctional Drug-loaded Microcapsules with Core-shell Three-dimensional Network Structure and their Application in Colon Targeted Release

Some special oral drugs may cause adverse reactions and degrade in the stomach; therefore, it is necessary to develop a new generation of multifunctional drug delivery carries to deal with such issues. Herein, by polyelectrolyte composite method using KGM and CS as raw material, CKGM/CS/TPP/5-ASA microcapsules are prepared using 5-ASA as model drug, and then coated with an acid-resistant polyacrylic acid polymer layer. The size of CKGM/CS/TPP/5-ASA microcapsules is relatively uniform, with average particle size 1.78 +/- 0.02 mm. The inner part of microcapsules has a core-shell three-dimensional network structure, and the 5-ASA embedded in the network is in its crystal form. The microcapsules exhibited good encapsulate properties, with 495.5 mu g mg(-1) drug loading amount and 82.3% encapsulation efficiency under optimized conditions. The in vitro release properties of microcapsules are also studied, and results showed that the drug is released little in Simulated Gastric Fluid solution (pH 1.2) but fully released in Simulated Colonic Fluid or Phosphate Buffered Solution (pH 7.0), and the release rate is higher in SCF solution, indicating that beta-mannanase could facilitate release. All these results indicated that CKGM/CS/TPP microcapsules have good pH-controlled release, enzymatic release, and sustained release properties, hence they are promising multifunctional colon-targeted release carriers.