中文摘要：

背景：普通淀粉经过增塑,强度和弹性大大增加,成为增塑淀粉,该材料分子量巨大、缠绕点多、对小分子具有超强包容性、凝胶化能力强, 可作为替代海藻酸盐的可降解材料, 并通过加入骨诱导因子, 成为具有止血及诱导成骨双重作用的组织工程材料; 还可用于口腔组织引导膜、烧伤后皮肤敷料等。目的： 通过细胞毒性实验,测试增塑淀粉的生物安全性。设计：观察对比实验。单位：北京市创伤骨科研究所;北京积水潭医院;北京化工大学;北京大学口腔医学院。材料：实验于2006-04/10在北京市创伤骨科研究所细胞实验室完成。增塑淀粉是通过将含水 12%的玉米淀粉与一定比例的甘油在哈克密炼机中熔融共混得到的, 温度和转速分别为 110 ℃和 80 r/min ,混炼时间 25 min,断裂伸长率 115.3%～245.3%;由北京化工大学北京市新型高分子材料制备与加工重点实验室研制。实验选用的小鼠成纤维细胞 L929 细胞株由北京大学医学部细胞库提供。方法： 在 1×10^7 L^-1 L929 细胞悬液中加入增塑淀粉后获得浸提液浓度为 50%,对照组为该悬液常规培养液。用 MTT 比色法定量测试材料对 L-929 细胞相对增殖率的影响, 并根据 GB/ T16175-1996 标准评估细胞毒性。应用倒置显微镜观察两组细胞培养 2,4,7d 后形态和生长状况。主要观察指标：①细胞毒性。②细胞形态及增殖情况。③细胞相对增殖率。结果：①细胞毒性：增塑淀粉组在培养 2, 4 d 后 A 值低于对照组,7 d后的 A 值高于对照组,差异有显著性意义（P 〈 0. 01）,提示培养 2,4 d后增塑淀粉组细胞毒性大于对照组,而 7 d 则相反;实验材料细胞毒性分级为 0～1。②细胞形态及增殖情况：培养 2 d 时两组细胞均未占满视野, 细胞形态呈三角、四边形, 对照组有梭形细胞;培养 4 d时细胞布满视野, 细胞生长旺盛。增塑淀粉组细胞间仍有间隙, 对?

英文摘要：

BACKGROUND： The strength and elasticity of general starch can be enhanced dramatically after plastic blends. The major characters of this material are magnitude molecular weight, many enwinded points, extreme containment of small molecules, and great gelation ability. It can be used as a biodegradable replacement of alginate. Furthermore, by adding osteoinductive factors, thermoplastics starch （TP） can be used as an organic engineering material, which can provide dual functions： anti-bleeding and bone formation. TP can also be used as intraoral tissue formation membrane and burn dressings. OBJECTIVE： To evaluate the bio-safety of TP through a cytotoxicity test. DESIGN： A controlled observation. SETTING： Beijing Research Institute of Traumatology and Orthopaedics; Beijing Jishuitan Hospital; Beijing University of Chemical Technology; Peking Univesity School of Stomatology. MATERIALS： The experiment was conducted at the laboratory of Beijing Research Institute of Traumatology and Orthopaedics from April to October in 2006. TP sample was obtained by plasticization of corn starch （12 wt % water content） with glycerol in a Haake Rheomix at 110℃ and with 80 rounds per minute for 25 minutes, elongation at break from 115.3% to 245.3%. It was prepared by Beijing Key Laboratory for Preparation and Processing of Novel Polymeric Materials, Beijing University of Chemical Technology. Mouse fibroblast L-929 cell strain was provided by the cell bank of Peking University Health Science Center. METHODS： 1× 10^7 L^-1 cell aqueous suspension was cultured into leaching liquor （ 50% ）, serving for TP group, and routine culture medium served for negative control group. Effect of TP on relative growth rate of L-929 cell strain was quantitatively measured by MTT assay. The cytotoxicity of TP was evaluated according to GB/TI6175-1996. Morphological changes and proliferation of cells were observed after2, 4, and 7 days of culture in the medium through an inverted phase contrast microscope. MAIN OUTCOME ME