目的 制备结构与天然软骨结构相似的仿生多层软骨支架。方法 采用先后于-20℃和液氮中冷冻的预冻方式，冷冻干燥法制备双层支架。采用-20℃冷冻后，部分熔融再液氮重冻的预冻方式，冷冻干燥制备了厚度约2mm的仿生多层软骨支架。采用XRD和红外光谱观察胶原和壳聚糖的复合情况。 采用SEM观察支架的形貌。对比了纯壳聚糖支架、纯胶原支架、胶原壳聚糖复合材料单层支架和仿生多层支架在干燥和湿润两种状态下的力学性能。结果 胶原和壳聚糖的复合存在化学反应，复合材料形成更好的孔结构，仿生多层支架从上至下分别具有致密层结构，圆形孔结构和垂直孔结构。支架材料在干燥和湿润状态下的力学性能有很大差别，仿生多层支架在湿润状态下各层具有不同的力学性能。结论 仿生多层软骨支架的结构接近于天然关节软骨多层结构，且在湿润状态下各层的力学性能有差异，有望更好地维持软骨细胞表型和提高软骨损伤修复效果。
Objective Prepare biomimetic multilayered scaffold which has similar structure of natural cartilage. Methods By lyophilizing the scaffolds which were prefrozen at -20℃ and in liquid nitrogen successively, we prepared double-layered spongy scaffolds. By partially thawing the prefrozen samples and refreezing them in liquid nitrogen before the final liyophilization, we prepared biomimetic multilayered scaffolds. XRD and FT-IR were used to confirm the interaction between collagen and chitosan. SEM was used to observe the morphologies of the scaffolds. The mechanical properties of pure chitosan scaffolds, pure collagen scaffolds, composite single-layered scaffolds and biomimetic multilayered scaffolds were compared. Results There is chemical interaction between collagen and chitosan. Composite materials eill form better pore structure. The biomimetic multilayered scaffolds had upright pores, round pores and a dense layer from bottom to top of the scaffolds. The scaffolds had quite different mechanical properties between dry and wet state. Under wet state, the different layers of the biomimetic multilayered scaffolds have different mechanical properties. Conclusions The biomimetic structure of the multilayered scaffold is very close to that of the natural articular cartilage, and the different layers of the biomimetic multilayered scaffolds had different mechanical properties under wet state. These are hopefully beneficial to help maintain the phenotypes of chondrocytes and promote the repairing effect of cartilage defects .