BACKGROUND:Calcium phosphate cements (CPCs) possess the bio-degradation and osteoconduction, and its final hydration product, hydroxyapatite, is the main inorganic constituent of bones. However, its poor mechanical property makes it unable to be used for repairing weight-bearing bone defects. OBJECTIVE:To develop a kind of bioactive bone cements with decent biomechanical property and biocompatibility. METHODS:6%silk fibroin aqueous solutions containing different concentrations of N-acetylcysteine (0, 10 and 25 mmol/L) were prepared. Each cement sample was prepared by mixing the curing liquid andα-tricalcium phosphate powder with the ratio of 0.4 mL:1 g;α-tricalcium phosphate powder mixed with ddH2O as control group. The compressive strength, setting time of the cements were measured. The crystal components of the cements were characterized using X-ray diffraction and the microstructure was observed using scanning electron microscope. MC3T3-E1 cel s were seeded onto the material in each group, and cel morphology was observed under scanning electron microscope at 24 hours. MC3T3-E1 cel s were cultured in the extract of each material, cel proliferation was detected at 1, 3, 5 and 7 days, and the lactate dehydrogenase level was detected at 1 and 3 days. RESULTS AND CONCLUSION:X-ray diffraction and scanning electron microscope showed that the final hydration products ofα-tricalcium phosphate in al specimens were hydroxyapatite. When the concentration of N-acetylcysteine was 25 mmol/L, the compressive strength of the material reached (49.39±1.68) MPa, with the initial setting time of (21.77±1.07) minutes and the final setting time of (31.88±1.69) minutes. There was no significant difference in cel morphology among cements. These results suggest that the cement containing N-acetylcysteine exhibites good biocompatibility and high mechanical strength.%背景：磷酸钙骨水泥具有骨传导性、可降解等显著优点，其水化产物羟基磷灰石为骨骼主要无机成分，然而其力学性能不足限制了在负重区域骨缺损修复的应用。目的：研制具有良好生物力学性能及生物相容性的磷酸钙复合骨水泥。方法：①配置含有不同浓度(0，10，25 mmol/L)N-乙酰半胱氨酸的6%丝素蛋白溶液，作为固化液；以α-磷酸三钙粉末为固体，按液固比0.4 mL：1 g制备含有不同浓度N-乙酰半胱氨酸的丝素蛋白磷酸钙骨水泥，同时设置α-磷酸三钙粉末与ddH2O混合为对照组。测定复合骨水泥的抗压强度、凝固时间，通过X射线衍射仪检测骨水泥晶体成分，扫描电镜观察骨水泥微观形貌；②将MC3T3-E1细胞接种于各组材料表面，24 h后扫描电镜观察细胞形态；③以各组材料浸提液培养MC3T3-E1细胞，1，3，5，7 d后检测细胞增殖，1，3 d后检测细胞培养基中乳酸脱氢酶含量。结果与结论：①X射线衍射和扫描电镜检测结果表明，各组材料中α-磷酸三钙的水化反应产物均为羟基磷灰石；②当N-乙酰半胱氨酸浓度为25 mmol/L时，材料的抗压强度最大，达(49.39±1.68) MPa，材料的初凝时间为(21.77±1.07) min，终凝时间为(31.88±1.69) min；③细胞在含有不同浓度N-乙酰半胱氨酸的丝素蛋白磷酸钙骨水泥表面的形态无明显差异；④含有不同浓度N-乙酰半胱氨酸的丝素蛋白磷酸钙骨水泥可促进细胞增殖，抑制乳酸脱氢酶分泌；⑤结果表明，N-乙酰半胱氨酸可显著提高丝素蛋白磷酸钙骨水泥的力学强度，具有良好的细胞相容性。
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