| One of the key factors of bone tissue engineering is an appropriate porous scaffolds which exhibits suitable material properties and biological performance, therefore it's an important aspect of tissue engineering to find a scaffold that have good biocompatibility and biodegradability, specific shaped and connected three-dimensional porous structure. The exist bone tissue engineering scaffolds had some performance that bone tissue engineering needed, but there still some of the demands that the exist scaffolds can not meet the requirements of bone tissue engineering. Hydroxyapatite (HAP) and chitosan (CTS) which have good biocompatibility and Konjac glucomannan (KGM) which has excellent gelling property were used in this work, in order to integrate together the advantages of the three materials above, and prepare a HAP/CTS/KGM three-dimensional porous scaffolds which can be used for bone tissue engineering.The main conclusions of the work are as follows:1) HAP/CTS composite powder was prepared by co-titration method at the conditions of room temperature and pH=10.00. HAP/CTS composite powder was included in KGM gel to prepare bone tissue engineering scaffold, in the condition of pH=9.6, via sol-gel method. Curing and alkaline removing were performed under water bath, then fabricated the HAP/CTS/KGM composite scaffold by freeze-drying method.2) The powders and the scaffolds were characterized by X-ray diffraction (XRD), Fourier Transform-Infrared Spectroscopy (FTIR), Transmission electron microscopy (TEM), TG/DTA and Scanning Electron Microscope (SEM), in order to investigate the structural feature and the bonds between HAP and CTS. The porosity, mean pore size and'the compressive strength were measured, in order to investigate the mechanical properties of the scaffolds. The BMSCs co-culture experiment and the in vivo implant were performed in order to investigate the biological property of the scaffolds.3) The mass ratio of HAP and CTS in the composite was 4.3:1, and there are two kinds of interactions (physical force and chemical force) in the HAP/CTS composite powder. The physical force occurred because some HAP particles adsorbed on the CTS chain, and the chemical force occurred since the chelation between the CTS and Ca2+(Ⅱ) ion. The Ca2+(Ⅱ) ion in the HAP particles and the amino in the CTS form a non-stoichiometric compounds by a method of coordination. The CTS molecular chain charged due to the ionophoresis in the reaction system, therefore there are a large number of HAP particles deposited on the surface of CTS via the electrostatic interaction. Chemical bonding is the main mode of interaction.4) The HAP/CTS/KGM composite scaffolds prepared above are three-dimensional network-like porous structure with the porosity between 86% and 91.5%. The central pore size of scaffolds situated between 145μm and 175μm and the pore ratio lies between 78% and 85%. The compressive strength was found 1.4 Mpa and 2.0 Mpa. There were bonds between acetyl of KGM and alcoholic hydroxyl group of CTS by dehydration. The amino and alcoholic hydroxyl group of CTS were also bonded. HAP and KGMwere bonded directly or through CTS. HAP particles play the role of enhancement of the KGM matrix.5) The samples No.2,3 and 12 were cultured with BMSCs. The results shown that: the samples of No.2 and 3 have better stem cells compatibility and mechanical properties.6) Considering the performances of the samples and Response Surface Analysis (RES), the best preparation conditions and component were as follows:①the titration speed of solution was Ca(OH)2/NH3·H2O 3.75 ml/min, H3PO4/CA-CTS 0.75 ml/min, pH=10.0, the stirring rate is of 15 rad/sec, the titration products were aged for 7 days under 4℃.②The pre-frozen temperature during the preparation of the scaffolds is-24.625℃. The gel were prepared under the condition of HAP/CTS contents up to 73.9%, pH=9.3, and aged another 28.9 hours under 75℃, alkaline were removed for 43.1 hours via water impregnantion, HAP/CTS/KGM scaffolds were prepared via freeze-drying. |
PDF Full Text Request