Degradation of PEG and non-PEG alginate-chitosan microcapsules in different pH environments

作者：Wong Yih Yong; Yuan Shaojun; Choong Cleo^*

来源：Polymer Degradation and Stability, 2011, 96(12): 2189-2197.

DOI：10.1016/j.polymdegradstab.2011.09.009

• Alginate
• Chitosan
• Polyethylene glycol
• Degradation
• Microcapsules

Bioencapsulation allows the protection of biologically active substances or cells from the biological environment. As such, bioencapsulation is often used for the delivery of drugs, growth factors and therapeutically useful cells. Depending on the site of implantation, the biocapsules are subjected to different pH environments, which will affect the degradation properties, mechanical properties and swelling behaviour of the biocapsules. As such, the encapsulation material plays an important role in the long term stability and performance of the biocapsules in vivo. In this study, five types of encapsulation materials were investigated: (i) alginate (A), (ii) alginate-chitosan (AC), (iii) alginate-chitosan-alginate (ACA), (iv) alginate-chitosan-polyethylene glycol (PEG) (ACP) and (v) alginate-chitosan polyethylene glycol (PEG)-alginate (ACPA). Degradation studies were carried out by immersing the microcapsules in solutions of different pH values to investigate the role of the material as well as the number of encapsulation layers in maintaining the stability of the microcapsules in the different pH environments. Compression testing indicated that even with the presence of PEG on the surface membrane, there was not much difference in mechanical strength between ACA and ACPA microcapsules. However, the use of PEG did affect the weight change of the ACPA microcapsules when immersed in water and three different pH solutions. For the swelling test, the ACPA microcapsules showed a lower water uptake than ACA microcapsules. For degradation, the presence of PEG led to a lower increase in weight change compared to non-PEG chitosan microcapsules. Hence, the study revealed that PEG influenced the integrity of the surface membrane and not the mechanical strength of the microcapsules. With the inclusion of PEG, the interpenetrating network on the surface membrane would be further reinforced. As such, the addition of PEG to the alginate-chitosan microcapsules led to protection against an acidic environment, whilst the number of coating layers only influences the swelling properties and not the degradation and Young';s modulus of the microcapsules.

• 出版日期2011-12
• 单位南阳理工学院