Chitin-based fast responsive pH sensitive microspheres for controlled drug release.

Ionically crosslinked chitin microspheres were prepared by using electrostatic droplet method and the drug release from the microspheres was controlled by adjusting external pH. Specifically, chitin was dissolved in NaOH/urea solution at low temperature and functionalized with acrylamide moieties. Acrylamide-modified chitin microspheres with a diameter of 400-500 μm can be obtained at the voltage of 6 kV and the pump speed of 5 mL h(-1). The formed microspheres were ionically crosslinked with Fe(3+) and then complexed with polycationic polysaccharide chitosan. The structure of the microspheres was characterized by FT IR, SEM, and EDS analyses. Besides, the drug release behavior of the microspheres exhibited a fast responsive and pH sensitive release of vancomycin. It took 30 h for complete release of vancomycin in pH 4.0 buffer and pH 1.2 HCl solution while a fast release (10 min) occurred in pH 7.4 buffer. The results showed that the microspheres could be used in drug delivery.