Effect of preparation method and characteristics of chitosan on the mechanical and release properties of the prepared capsule

Abstract

The objective of this study is to elucidate the effect of preparation method and the characteristics of chitosan used on the mechanical and release properties of the prepared capsule. The characteristics of the chitosan explored include molecular weight (1.8, 5.6, 20.2, and 31.8 × 105 Dalton) and chain flexibility parameter (B), which was manipulated by a varying degree of deacetylation (DD, 67.9, 81.3, 90.5, and 92.2%), and sodium chloride concentration (0 or 0.3%). The orifice method was used to encapsulate hemoglobin, whereas complex coacervation was used to encapsulate the bovine serum albumin (BSA). The axial ratio was measured to characterize the appearance of the capsule. Break strength was used as an index of mechanical strength. Release percent of protein was used as a pore size indicator. The results show axial ratio and hemoglobin release percent of the capsule prepared by the orifice method increased with the increase of the chain flexibility parameter (B), but decreased with the increase of the chitosan molecular weight. However, break force behaved just opposite from that of the axial ratio and release percent of hemoglobin. The capsule cannot be prepared from 92.2% DD chitosan. Break strength and BSA release percent of the capsule prepared by complex coacervation did not vary with different DD, molecular weight of chitosan, and sodium chloride concentration.