| Hydroxyapatite and collagen protein are main inorganic and organic component of natural bone, and both of them have good biocompatibility. Nevertheless, the application of single material is very limitated to satisfy the needs of tissue engineering. The composite of HAP/Col protein enables the adhesive property of collagen protein and combines of HAP grain. In this paper, the nano-HAP/Col protein and micro-HAP/Col protein composite were studied to improve the properties of pure materials.Firstly, HAP powder was prepared by acid and alkali neutralizational method. The optimized process of HAP powder preparation was investigated by orthogonal experiment method. Meanwhile, as prepared HAP powder and collagen protein were adopted as raw material to form ceramic slurry. Making use of the adhesive property of collagen, the multi-phase (HAP and Col protein) porous scaffold material with three-dimensional pores was prepared via physical foaming mehtod. The crystallite phases, microstructure, porosity, mechanical property and distribution of pore size of porous scaffold materials were systematically characterized via XRD, SEM, Archimedes principle, lever principle, mathematical statistics method etc. The biodegradability of multi-phase porous scaffold materials were investigated preliminarily by simulated biodegradation experiments.The results showed that the high-purity HAP powder could be fabricated by acid and alkali neutralizational method through the system of 10Ca(OH)2+6H3PO4â†'Ca10(PO4)6(OH)2+18H2O via controlling pH value at 8～9, with the reactant passing through 400 mesh, keeping reaction more than 17 hours about 40℃, then the precipitate was heat-treated 5 hours at 750℃after ageing, washing and drying. HAP/Col protein porous scaffold materials with porosity of 59～81% and mechanical strength of 0.77～1.98 MPa could be prepared via physical foaming method, moulding, freeing and micro-wave drying. The diameter of pores is less than 800μm, the percent of 100～700μm pore is 63.5%, which is 74.3% of all the pore volume. Pores are connected each other and shows irregular shape. This porous scaffold materials with different content of collagen protein possessed different dissolving biodegradability in vitro. But with rising of the content of collagen protein, the dissolving biodegradability were increased.Secondly, Nano-hydroxyapatite/collagen protein composite scaffold materials were synthesized from the supernate of saturated Ca(OH)2 solution, phosphoric acid and collagen protein, by simultaneous titration. Crystallite phases, crystallization, micro-morphology, crystallite size and chemical bond, were characterized by XRD, SEM, TEM and IR. The biodegradability of composite materials were investigated preliminarily by simulated biodegradation experiments.The results showed that HAP in the composite was 5×60nm～20×100nm acicular crystals, the collagen protein was catenarian, two or three collagen protein chains were cross-linked each other to form clusters, while HAP were deposited evenly on the collagen protein cluster. The preferentia oriention of HAP nanocrystals was strongly at the diffractive face of (002) and (004), and it had the trend of preferentia oriention at the diffractive face of (211) and (310). The chemical bond was formed between hydroxyapatite and collagen protein. The main location of HAP nucleation on collagen protein fibres was carboxyl and carbonyl. The carbonation similar to natural bone occurred in the course of nucleation. Composite powder and water were mixed by 1:1.3wt, they became cream materials and could be extruded from injector. Composites may be used in clinical tiny wound surgery. |
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