Interaction of anionic collagen with chitosan: Effect on thermal and morphological characteristics

This work describes the freeze-drying technique preparation and characterization of porous scaffolds (sponges) of blends between chitosan and anionic collagen. Chitosan (CHI) was obtained from the partial deacetylation of squid pen chitin and the anionic collagen was prepared by alkaline hydrolysis of porcine serosa at different times (COL24, COL48, COL72 and COL96 h). Separate materials and sponges (1:1) were characterized by thermal analysis (DSC, TG/DTG), FT-IR and SEM. The time course of alkaline hydrolysis in a collagen structure has a remarked influence on sponge properties. In DSC curves, negative net charge increased in the collagen molecules reducing the denaturation temperature in the sponges, 58.4 °C (CHI:COL24) to 49.2 °C (CHI:COL72). In TG/DTG curves the collagen presence influenced the thermal stability, whose tendency for degradation temperature reduced (155, 148.8 °C at CHI:COL24 and CHI:COL96, respectively). Different mean pore sizes were observed for the sponges, where a great reduction of the pore size with alkaline hydrolysis time occurred, which varies from 88.5 ± 7.4 (CHI:COL24) to 59.1 ± 8.6 (CHI:COL96).