Preparation And Study Of An Artificial Bone-recombinant Human-like Collagen â…¡ Biomimetic Composite Material

With the development of tissue engineering, especially bone tissue engineering, biomimetic material for artificial bone has attracted more and more attention. As mainly organic ingredient of natural bone, collagen is not only the support for osteoblast to adhere, but also has the important induction to the ore deposit. Therefore, it has become the hot spot in bone tissue engineering research. RHLC II (recombinant human-like collagen II) as a kind of recombinant collagen was produced by high cell-density cultivation of recombinant Escherichia coli containing a partial cDNA that was reversed by mRNA from human collagen. RHLC II can eliminate the restriction of virus from animal collagen, and have the characteristics of low cost and being easily industrialized by large scale. So it has extremely high applied value and market prospect. The preparation of scaffold is the vital material base for the application of RHLC II in bone tissue engineering field. From bionics view, RHLC II composite material as an artificial bone was developed by phase separation-freeze drying method in this paper. We studied the physical and chemical properties and biocompatibility of RHLC II composite material.1,RHLC II as major stuff, RHLC II composite material as an artificial bone was developed by phase separation-freeze drying method. The physical and chemical properties of RHLC II composite material was determined by porosity experiment, SEM, TEM, XRD, FTIR and electronic universal-testing machine. The results as follows: (1) The porosity was greater than 85%; (2) The pore sizes were between 60 and 300μm, and the pores interpenetrated; (3) Hydroxyapatite crystals were at nanometer level (the diameter was 20-30nm); (4) The inorganic phase was hydroxyapatite in low crystallinity, and did not have other Ca -P salt; (5) RHLC II composite material was mainly composed of collagen and carbonic hydroxyapatite, and chemical action took place between hydroxyapatite and chitosan intermolecularly; (6) Compressive strength and modulus of elasticity of the material were higher than that of cortical bone and lower than that of dentine. The results showed that the structure and chemical composition of RHLC II composite material were similar to that of natural bone, and the pore size, porosity and mechanical properties satisfied the request of bone repairing material.2,According to the biological evaluation criteria and request of medical instrument in ISO 10993-1992 and GB/T 16886-1997, acute systemic toxicity test, hemolytic test, intracutaneous irritation test and pyrogenic reaction test were chosen to evaluate the biosecurity and the biocompatibility of RHLC II composite material as an artificial bone. The material presented negative results in those experiments: (1) Apparent toxic performances were not observed in animals of the material team; (2) The hemolytic ratio was 2.93% (smaller than 5%); (3) The APII was 0.27 point (smaller than 0.4 point); (4) For the three experimental animal, the rise of body temperature for everyone were lower than 0.6℃, and the rise for total was lower than 1.4℃. The results indicated that RHLC II composite material did not have the biological toxicity, and had good biocompatibility.