| Scaffold for bone tissue-engineering is one of the hotspots in biomaterial research fields. The scaffold, acting as the carrier materials of bone tissue cells, should possess good biocompatibility, controllable biodegrade rate, proper pore size and porosity, suitable mechanical strength and suitable interface of the materials and cells.β-tricalcium phosphate(β-TCP) is similar to inorganic content of natural bone, and possesses a good biocompatibility. However,β-TCP has disadvantages such as brittleness, poor toughness and high elastic modulus, which limits its application in clinic. PLLA used as bone- repaired material has good biocompatibility and biodegradability, but its low mechanical strength and acid degradation production also limit its application in clinic. To meet the demand for mechanical and biological properties of bone replacement materials, composite materials composed of inorganic ceramic and polymer have been extensively studied.β-TCP and polylatic acid (PLLA) which possessed good biocompatibility and biodegradability have been selected for preparing PLLA/β-TCP porous scaffold, and the mechanical and biological performances of PLLA/β-TCP porous scaffold have been studied in the present research.1. PLLA/β-TCP composite particles were firstly deposited from chloroform solution by using the method of solvent self-diffusion. The influence of different diffusion medium on this deposit process was studied. The results showed that the mixture of acetone/ethanol as the diffusion media was best in all the diffusion mediums, as thedeposit speed could be fast and more composite particles could be obtained. The macro-porous composite scaffolds were fabricated by compression molding and salt-leaching. The residual solvent of porous scaffold was tested. The results showed that the residual quantities of chloroform, acetone, and ethanol were 36.30ppm, 2.07ppm, and 25.17ppm, respectively. The particle size and content of porogen, the ratio of PLLA/β-TCP and molding pressure have important affects on properties of scaffolds. The orthogonal design was used to optimize the experimental parameters. The results showed that the pores structure of composite scaffold was interconnected, the compressive strength was 4.45MPa and porosity was 60.7%, which was fabricated under the optimal conditions that PLLA:β-TCP=1:2, molding compression 5Mpa, the particle size of porogen 125～400μm and percentage content 80wt %.2. The biodegradation tests in vitro were carried through immersing the composite scaffolds in stimulated body fluid (SBF) under static and flow state respectively. The molecular weight of PLLA, mass increase rate, porosity changes, change of compressive strength and elastic modulus were measured, and the samples were characterized by SEM, IR, and XRD spectrum. The results showed that all scaffolds could maintain their shape after degradation for 24 weeks, bone-like apatite could be formed upon the surface of scaffolds and also the inside as time goes on. And the degradation speed could be adjusted with the ratio ofβ-TCP and PLLA. After 24 weeks, porosity and strength of the scaffolds decreased while the mass of the scaffolds increased.3. Canine mesenchymal stem cells,cMSCs and EA.Hy926 endothelial cells were cultured with PLLA/β-TCP porous scaffolds in dynamic culture (in the reactor) and static culture (in the 24-well plate). The results showed that cMSCs and EA.Hy926 endothelial cells could attach and proliferate on scaffold, and the cell did not appear obvious abnormity in morphology. So it was indicated that the scaffold could not disturb the biological behavior of cMSCs and EA.Hy926 endothelial cells. It also showed that cells in dynamic culture were growing more bloomingly and metabolizing more rapidly than those in static culture.
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