Fabrication and characterization of Chinese giant salamander skin composite collagen sponge as a high-strength rapid hemostatic material

Chinese giant salamander (CGS) has high medicinal value and long history of clinical use in ancient China. In this study, CGS skin (CGSS) collagen was extracted and purified to prepare collagen sponge by freeze-drying. TEMPO oxidized microfibrillated cellulose (TEMPO-MFC) and genipin were adopted to improve the mechanical properties of collagen sponge. The hygroscopicity, porosity, mechanical properties, hemostatic performance, morphology, and biodegradability of the resultant sponges were investigated in detail. The results indicated that CGSS collagen was type I collagen with intact triple-helical structure, and the prepared sponge had porous structure and excellent hemostatic performance with procoagulant ratio of 53.28%. However, the CGSS collagen sponge showed low tensile strength (TS) of 98.80KPa, compression strength (CS) of 1.48KPa, and elongation at break (E) of 4.72%. Incorporating 2.5% TEMPO-MFC into the native CGSS collagen sponge resulted in an increase of 188.26% in TS to 284.80KPa, 166.89% in CS to 3.95KPa, and 73.52% in E to 8.19%. The improvements were attributed to the physical filling of TEMPO-MFC in cavity and cavity wall of collagen sponge and the stable chemical linkage between carboxyl of TEMPO-MFC and amino group of collagen which effectively improved the toughening of sponge and formed good interface bonding, respectively. Subsequent 0.3% genipin treatment further improved the TS to 605.00KPa and the CS to 8.66KPa as a result of crosslinking reaction. Moreover, the composite reinforcing also improved the anti-degradation ability and procoagulant ratio of collagen sponge. All results suggested that the TEMPO-MFC toughened and genipin crosslinked CGSS composite collagen sponge is a promising rapid hemostatic material with high-strength and can be applicated in biomedical field.