A pH-sensitive nanocomposite microsphere based on chitosan and montmorillonite with in vitro reduction of the burst release effect

Objective: The aim of this study was to prepare pH-sensitive ofloxacin (OFL)/montmorillonite (MMT)/chitosan (CTS) nanocomposite microspheres that improve the burst release effect of the drug by the solution intercalation technique and emulsification cross-linking techniques. Methods: First, OFL/MMT hybrids were prepared through the solution intercalation technique. Then, OFL/MMT-intercalated OFL/MMT/CTS nanocomposite microspheres were obtained through emulsification cross-linking technology. The intercalated nanocomposite was confirmed by Fourier-transform infrared spectroscopy and X-ray diffraction. Finally, in vitro release of OFL from the microspheres was performed in simulated gastric fluids and simulated intestinal fluids. The effect of MMT content on drug encapsulation efficiency and the drug release of the nanocomposite microspheres were investigated. Results: The results showed that the release rate of OFL from the nanocomposite microspheres at pH 7.4 was higher than that at pH 1.2. Compared with pure CTS microspheres, the incorporation of certain amount of MMT in the nanocomposite microspheres can enhance the drug encapsulation efficiency and reduce the burst release. Conclusion: A sustained release particulate system can be obtained by incorporating MMT into the nanocomposite microspheres and can improve the burst release effect of the drug.