Influences of Process Variables on Size of Chitosan Microspheres

Abstract

Chitosan microspheres, with a size range of 20–550 μm, were obtained by using an emulsification–coacervation method. The surface morphology and the structure of microspheres were characterized by scanning electron microscopy and X-ray diffraction. The effects of process variables, including stirring rate, chitosan concentration, emulsifier concentration, and cross-linker (glutaraldehyde) concentration, on the diameter of chitosan microspheres were investigated. The results showed that spherical microspheres, without aggregation phenomena and with a very smooth and uniform surface, were obtained when emulsifier concentration, chitosan concentration, stirring rate, and glutaraldehyde concentration were kept at 0.010–0.025 mL/mL, 0.05–0.20 g/mL, 800–2400 rpm, and 0.5–1.5% (v/v) respectively. The chitosan microsphere crystallinity degree decreased after cross-linking. The microsphere size increased with decreasing of stirring rate, emulsifier, and cross-linker concentration; however, the microsphere size increased with increase of chitosan concentration. This indicated that different diameters of chitosan microspheres can be achieved by controlling process variables.

Keywords:

• chitosan
• microspheres
• process variable
• size

Acknowledgment

This project was financially supported by the National Natural Science Foundation of China (No. 51142001), the Hunan Provincial Natural Science Foundation of China, the Research Foundation of Education Bureau of Human Province, China (Nos. 10A098 and 11B099), and the Planned Science and Technology Project of Hunan Province, China (No. 2011TT2038).