[Study on homogeneity of enzymatic degradation of chitosan as biomaterials by gel permeation chromatography].

Chitosan is an important biomedical material, and its degree of deacetylation is a main parameter of its biodegradation. Gel permeation chromatography was used to investigate the lysozymic degradation of two types of chitosan samples (A and B) with similar degree of deacetylation and relative molecular mass but with different distributions of two units of N-acetyl-D-glucosamine and D-glucosamine. Weight average relative molecular mass, polydispersity and gel permeation chromatograms during the degradation process were obtained. It was found that chitosan sample A with random distribution of the two units underwent a homogeneous degradation process while chitosan sample B with block distribution underwent a heterogeneous degradation process. The results suggest that the homogeneity of the degradation of chitosan materials by lysozyme depends on the distribution type of the two units, which can help to design chitosan-based biomedical devices.

The enzymatic degradation and swelling properties of chitosan matrices with different degrees of N-acetylation.

In the design of chitosan-based drug delivery systems and implantable scaffolds, the biodegradation rate of the chitosan matrix represents a promising strategy for drug delivery and the function of carriers. In this study, we have investigated the degradation of chitosan with different degrees of N-acetylation, with respect to weight loss, water absorption, swelling behavior, molecular weight loss of bulk materials, and reducing sugar content in the media. Chitosan matrices were prepared by compression molding. The results revealed that the initial degradation rate, equilibrium water absorption, and swelling degree increased with decreasing degree of deacetylation (DD) and a dramatic rise began as DD of the chitosan matrix decreased to 62.4%. Chitosan matrices with DD of 52.6%, 56.1%, and 62.4% had the weight half-life of 9.8, 27.3, and more than 56 days, respectively, and the weight half-life of average molecular weight 8.4, 8.8, and 20.0 days, respectively. For chitosan matrices with DD of 71.7%, 81.7%, and 93.5%, both types of half-life exceeded 84 days because of the much slower degradation rate. The dimension of chitosan matrices during degradation was determined by the process of swelling and degradation. These findings may help to design chitosan-based biomedical materials with predetermined degradation timed from several days to months and proper swelling behaviors.