Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus.
Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus; Department of Pediatrics, University of Colorado Anschutz Medical Campus; Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus;
J Vis Exp. 2023 Jun 30(196). doi: 10.3791/65639.
Phototunable hydrogels can transform spatially and temporally in response to light exposure. Incorporating these types of biomaterials in cell-culture platforms and dynamically triggering changes, such as increasing microenvironmental stiffness, enables researchers to model changes in the extracellular matrix (ECM) that occur during fibrotic disease progression. Herein, a method is presented for 3D bioprinting a phototunable hydrogel biomaterial capable of two sequential polymerization reactions within a gelatin support bath. The technique of Freeform Reversible Embedding of Suspended Hydrogels (FRESH) bioprinting was adapted by adjusting the pH of the support bath to facilitate a Michael addition reaction. First, the bioink containing poly(ethylene glycol)-alpha methacrylate (PEGαMA) was reacted off-stoichiometry with a cell-degradable crosslinker to form soft hydrogels. These soft hydrogels were later exposed to photoinitator and light to induce the homopolymerization of unreacted groups and stiffen the hydrogel. This protocol covers hydrogel synthesis, 3D bioprinting, photostiffening, and endpoint characterizations to assess fibroblast activation within 3D structures. The method presented here enables researchers to 3D bioprint a variety of materials that undergo pH-catalyzed polymerization reactions and could be implemented to engineer various models of tissue homeostasis, disease, and repair.
光响应水凝胶可以对外界光照刺激进行时空响应转换。将这类生物材料整合到细胞培养平台中，并动态地触发变化，如增加微环境硬度，可以使研究人员模拟细胞外基质（ECM）在纤维化疾病进展过程中的变化。本文提出了一种在明胶支撑浴中进行 3D 生物打印光响应水凝胶生物材料的方法，该材料能够在其中进行两次连续的聚合反应。通过调整支撑浴的 pH 值以促进迈克尔加成反应，对 Freeform Reversible Embedding of Suspended Hydrogels（FRESH）生物打印技术进行了调整。首先，含有聚乙二醇-α甲基丙烯酸酯（PEGαMA）的生物墨水与可细胞降解的交联剂进行了化学计量外反应，形成了软水凝胶。然后将这些软水凝胶暴露于光引发剂和光线下，以引发未反应基团的均聚合反应并使水凝胶变硬。该方案涵盖了水凝胶合成、3D 生物打印、光交联和终点特性评估，以评估 3D 结构内成纤维细胞的激活情况。本研究提出的方法使研究人员能够 3D 生物打印各种经历 pH 催化聚合反应的材料，并可用于构建各种组织稳态、疾病和修复模型。
