Preparation And Biocompatibility Of Collagen Scaffolds

Collagen is the most widely distributed protein in vivo which has been used in medical equipment due to good biodegradability and biocompatibility. Type I collagen is the main composition of beaver’s tail tendon and beaver possess 98% gene similar with human beings. In the point of biomimetic engineering, we optimized extraction program of collagen based on traditional process. Collagen sponge and PNIPAAm/Collagen I semi-interpenetrating thermo-sensitive hydrogels as cell carrier were prepared.The acid extraction using a slight pepsin solubilization, type I collagen was extracted at low temperature. Infrared spectroscopy, UV spectroscopy, circular dichroism, gel electrophoresis and amino acid analysis inferred that extraction were matched with type I collagen feature. Collagen scaffolds were prepared by freeze-drying. Compared with the commercial gelatin sponge, collagen scaffolds absorbed more body fluids. Results showed that scaffolds present no potential cytotoxicity.The thermo-sensitive collagen hydrogels with semi-interpenetrating polymer network (semi-IPN) were successfully prepared by inducing type I collagen into poly (N-isopropylacrylamide) cross-linked network. The chemical composition and pore structure of the semi-IPN gels were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Swelling ratio measurement and differential scanning calorimeter (DSC) were used to investigate the thermo-sensitivity of hydrogels and contact angle was studied to analyze gels surface hydrophilicity. Additionally, L929 cells’behaviors such as adhesion, proliferation and detachment were carefully studied via cell culture on the surface of PNIPAAm/Collagen I semi-IPN hydrogels in vitro. The results indicated that the PNIPAAm/Collagen I semi-IPN hydrogels exhibit excellent thermo-sensitivity and biocompatibility. Cell cultures of L929 on the semi-IPN hydrogels showed better proliferation and viability than on the PNIPAAm hydrogel. By lowering temperature below the lower critical solution temperature (LCST), L929 cells could spontaneously detach from the surface of gels. Meanwhile, the detached cells were collected for typan blue staining and hematoxylin and eosin staining. Figures showed that extracellular matrix proteins and trans-membrane proteins were hydrolysed by trypsin digested. Cells spontaneously detached from the semi-IPN hydrogels showed higher viability than those from PNIPAAm hydrogel, which suggest that the semi-IPN hydrogels exist potential value in tissue engineering.