柠檬酸改性壳聚糖水凝胶的制备与性能

采用多元有机酸柠檬酸（CA）对壳聚糖（CS）进行改性,并通过冷冻-凝胶处理形成CS-CA水凝胶来提高CS的湿态力学性能。采用红外吸收光谱分析CA改性CS的作用机理,通过扫描电镜（SEM）、孔隙率、吸水动力学及拉/压力学性能测试优化CA的添加量（m（CA）∶m（CS-CA））和CS与CA在乙醇水溶液中的质量分数（w（CS-CA））。结果表明：CA主要是通过其结构中含有的羧酸位点与质子化CS的NH₃⁺形成稳定的离子键进行物理交联;冷冻-凝胶处理可得到孔隙互相连通的多孔结构CS-CA水凝胶;当m（CA）∶m（CS-CA）=0.3、w（CS-CA）=3%时可获得性能最优的CS-CA水凝胶。     

丝素蛋白溶液诱导成骨分化及其性能评价

BACKGROUND: Silk fibroin, as a kind of high-performance biomaterial, has been widely used to construct scaffolds in bone tissue engineering. However, whether silk fibroin itself holds osteoinductive ability has not been reported yet. OBJECTIVE: To investigate the impact of different concentrations of silk fibroin solution on the proliferation and differentiation of rat bone marrow mesenchymal stem cells (BMSCs) in vitro. METHODS: Silk fibroin and BMSCs were respectively isolated from silkworm cocoon and rat tibia, and were identified. Then, BMSCs were cultured in different concentrations of silk fibroin solution (0.01%, 0.05% and 0.1%), and the cell proliferation and the alkaline phosphatase activity were detected at different time points. RESULTS AND CONCLUSION: FTIR spectra of the sample extracted from silkworm cocoon showed distinct absorption peaks at 1 653 (amide I), 1 530.5 (amide II) and 1 212.3 cm-1 (amide III), which could be confirmed to be silk fibroin. Thus generated BMSCs showed long fusiform or astral morphology, positive for representative markers (CD29, CD44 and CD90) relating to mesenchymal stem cells, and could differentiate into osteocytes, chondrocytes and adipocytes under specific induction conditions, which further confirmed the extracted cells were BMSCs. Compared with the control group (without silk fibroin), 0.05% silk fibroin not only significantly promoted the cell adhesion, migration and proliferation, but also enhanced the alkaline phosphatase activity (P < 0.01). With the increasing of the silk fibroin concentrations, the osteodifferentiation capacity of the BMSCs was progressively improved within the range of 0-0.05% and then declined at 0.01% of silk fibroin solutions. These results suggest that silk fibroin can promote osteogenesis, thus providing scientific evidence for developing silk fibroin-based tissue-engineered scaffolds.