基于耦合交联的核壳结构同轴生物打印工艺及成形机理研究

To achieve functional breakthrough and application of bioprinting, the key is to choose hydrogel with excellent biological compatibility and develop stable printing process. At present, GelMA has been validated for cell growth, and gradually becomes a preferred material for bioprinting. Because GelMA has a low viscosity and slow crosslinking speed, existing methods tend to print 3D structures by regulating its rheological properties and crosslinking properties. However, the process is complex and has a low forming precision..Different from traditional strategy which requires a good process ability of bioink, the current project develops a novel fabrication method of core-shell structures using coaxial bioprinting, which is based on coupling crosslinking of alginate and GelMA. This method can both achieve biological function and forming quality of the printed structures. At first, the shell of microfilament is formed based on ionic crosslinking of alginate. Then GelMA is covalent crosslinked to form the core under constraint of the outer shell. Finally, 3D structures can be fabricated by controlling the crosslinking process to realize fusion of adjacent core-shell microfilaments. In order to achieve shape-control manufacturing, this project focuses on studying the forming mechanism and the printability of core-shell structures. Moreover, in order to achieve function-control manufacturing, the influence of process paramaters on degradation of the outer shell is investigated, and a function inducing model of vascular endothelial cells is printed. This method can be applied to other bioink with excellent biological compatibility but bad forming ability. The implemention of the project will promote realization functional breakthrough of bioprinting.

实现生物打印功能化突破及应用，关键在于选用生物兼容性优异的水凝胶并开发稳定的打印工艺。GelMA凝胶已被验证适于细胞生长，并逐渐成为生物打印的首选材料。但GelMA粘度低、交联速度慢，现有方法大都通过调控其流变和交联特性实现结构打印成形，工艺复杂、成形精度低。.本项目打破传统策略下对生物墨水成形能力的限制，直接从打印目标出发，兼顾生物功能性和结构成形性，提出一种基于耦合交联的核壳结构同轴生物打印新工艺。利用海藻酸钠离子交联形成凝胶微丝的外壳层，进而使GelMA在外壳层的约束下光交联形成内核层，并控制交联进程使凝胶微丝融合形成三维结构。通过研究耦合交联作用下的成形机理及工艺参数对可打印性的影响规律，解决控形制造难题；通过研究工艺参数与外壳层降解速度的规律关系及构建内皮细胞功能诱导模型，解决控性制造难题。该工艺可以推广至其他生物兼容性优异但难成形生物墨水的打印，促进生物打印从制造到应用的跨越。

生物3D打印通过操纵含细胞墨水构造活性组织模型，在组织修复及药物筛选中有广泛应用前景。由于生物墨水具有软、湿、脆三大特性，在生物活性及打印时流变特性的约束下，提升打印质量从而实现精准成形是一个难题。. 项目旨在将生物兼容性优异的GelMA水凝胶用于生物打印，实现GelMA水凝胶的打印精度提升及量化品控。针对非粘性光交联GelMA水凝胶不易打印、打印结构生物相容性不佳、打印结构无法功能化的难题，项目提出多种针对性打印策略，具体研究内容包括：（1）对不同取代率的GelMA水凝胶理化性能进行系统性的研究与分析，为后续GelMA水凝胶结构成型及功能化的实现提供相应的理化性能依据。（2）通过引入纳米黏土，设计了纳米粘土改性GelMA水凝胶的辅助支撑策略，在保留GelMA生物相容性的同时，显著提高了GelMA的可打印性和物理性能。（3）提出了基于耦合交联的GelMA墨水打印策略，可稳定、批量地制造高生物活性GelMA结构，并应用于血管类器官模型的制造。（4）研究了逐点光固化原理的GelMA生物3D打印工艺，并研制了低成本光固化生物3D打印设备。. 项目研究成果已应用于生物墨水、生物打印机等商业化产品，为组织工程和再生医学研究提供了有利工具和技术支持。.