软骨损伤是老龄化或特殊职业过度使用导致，而随着全球趋于老龄化，需要进行软骨损伤修复的患者日益增多。为解决大面积损伤修复供体不足问题。本文利用凝胶与活性陶瓷形成复合材料，并探讨了利用3D打印技术实现生物支架的制备。本文主要研究内容及结果如下：

（1）复合材料支架的制备研究。在天然生物材料透明质酸（Hyaluronic，HA）和海藻酸钠（Alginate，Al）构成的复合溶胶体系中引入羟基磷灰石（Hydroxyapatite，HAP）颗粒，室温条件下，在交联剂CaCl₂溶液的作用下形成复合材料支架。实验结果表明：在HAP填充量为1wt%时，复合材料的孔隙数量随着HAP颗粒粒径的增大而增多；小于30μm的颗粒粒径制备的复合材料亲水性能更好，状态更加稳定，降解速率更快；而在HAP颗粒粒径在50~80μm之间时，当HAP的含量低于4wt%时，复合材料的孔隙率随HAP的填充量增多而增大；当HAP含量高于4wt%时，复合材料的孔隙率随HAP填充的增多而减小。通过对支架材料的溶胀与动电位实验，其分析结果表明：HAP的过多填充会降低复合材料的溶胀率；复合材料水溶胶的Zeta电位的绝对值随着HAP含量的增多而变大，说明含有HAP的水溶胶有良好的稳定性，可作为易于储备的生物墨水。

（2）探索复合材料支架挤出式打印的方法。通过改善挤出喷头、墨水配比和交联剂溶液浓度，实现挤出式制备复合材料支架的研究。研究结果表明：改良挤出喷头前端，外扩交联剂挤出通道，可以实现微丝成型打印；随着Al浓度的增加，复合凝胶的形变率增大，凝结时间略微缩短；交联剂CaCl₂溶液浓度与复合凝胶的形变非线性相关，1mol/L的CaCl₂溶液适合用在挤出式3D打印。

（3）泰森多边形立方体在软骨修复应用的研究。软骨组织支架对孔隙率及抗压能力均有一定需求，仅考虑结构的影响。利用Voronoi图特性衍生设计出泰森多边形立方体，使用Rhino软件以实现功能梯度支架的设计，改变压缩因子和离散点数目得到构型不同的泰森多边形立方体。结果表明：泰森结构的抗压能力随压缩因子的减小而增强，随离散点数目的增大而减少。实验结果中抗压能力最优的泰森模型数据参数为0.7压缩因子和25离散点数目，最高能够抵抗480.3N。

总之，通过天然凝胶与活性陶瓷复合材料支架研究，结合3D打印技术，可以获得具有优异力学性能和多孔隙的医用凝胶基陶瓷复合材料。

Cartilage damage is a result of aging or overuse of specific occupations, and as the world tends to age, the number of patients requiring cartilage damage repair is increasing. To address the shortage of donor for extensive injury repair. In this paper, we use gels and activated ceramics to form composite materials and discuss the preparation of biological scaffolds using 3D printing technology. The main research contents and results of this paper are as follows:

 

Study on the preparation of composite scaffolds. Hydroxyapatite(HAP) particles were introduced into the composite sol-gel system composed of natural biomaterial hyaluronic acid and sodium alginate, and the composite scaffolds were formed under the action of the cross-linking agent CaCl₂ solution at room temperature. The experimental results showed that the number of pores of the composites increased with the increase of the particle size of HAP when the filling amount of HAP was 1 wt%; the composites prepared with particle size less than 30 μm had better hydrophilic properties, more stable state and faster degradation rate; while in the particle size of HAP between 50 and 80 μm, when the content of HAP was less than 4 wt%, the porosity of the composites increased with HAP filling increased; when the content of HAP was higher than 4wt%, the porosity of the composites decreased with the increase of HAP filling. The analysis results of the swelling and kinetic potential experiments on the scaffold materials showed that: the overfilling of HAP decreases the swelling rate of the composites; the absolute value of the zeta potential of the composite hydrosols becomes larger with the increase of HAP content, which indicates that the hydrosols containing HAP have good stability and can be used as easy-to-stock bioink.

 

Exploration of extrusion-based printing of composite scaffolds. The study of extrusion-based preparation of composite scaffolds was achieved by improving the extrusion nozzle, ink ratios and crosslinker solution concentrations. The results showed that: the improved extrusion nozzle front end and externally expanded crosslinker extrusion channel can realize microfilament forming printing; the deformation rate of composite gel increased and the coagulation time was slightly shortened with the increase of Al concentration; the concentration of crosslinker CaCl2 solution was non-linearly correlated with the deformation of composite gel, and the 1 mol/L CaCl2 solution was suitable for extrusion-based 3D printing.

 

Study of Voronoi cubes in cartilage repair applications. Cartilage tissue scaffolds have a need for porosity and compressive capacity, considering only the effect of structure. The Voronoi cubes were designed by using the characteristic derivation of Voronoi diagram, and Rhino software was used in order to realize the design of functional gradient scaffolds, and the Voronoi cubes with different configurations were obtained by changing the compression factor and the number of discrete points. The results show that the compression resistance of the Voronoi structure increases with the decrease of the compression factor and decreases with the increase of the number of discrete points. The data parameters of the Voronoi model with the best compressive capacity are 0.7 compression factor and 25 number of discrete points, which can resist up to 480.3N.

 

In conclusion, medical gel-based ceramic composites with excellent mechanical properties and porosity can be obtained through the study of natural gel and active ceramic composite scaffolds, combined with 3D printing technology.

 

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