Biomimetic dense collagen gel bioinks for automated biofabrication and 3D bioprinting

增材制造和三维生物打印技术最近在开发生物材料方面产生了很大的兴趣，例如在生物制造组织工程支架、医疗设备和模拟健康和疾病状况的体外组织样结构中，从而实现高通量药物筛选和诊断工具。3D生物打印依赖于将组织特异性细胞逐层沉积到水凝胶（称为生物墨水）中，以形成模拟人体天然细胞外基质的复杂分层结构。因此，组合物、3D生物打印性以及所得的生物墨水结构和机械性能对于成功都是至关重要的，并且理想地，这些将尽可能最好地模拟天然组织细胞外基质。形成纤维的I型胶原蛋白分子是存在于我们体内的天然支架材料。它为许多组织提供了许多关键的生物学和机械特性。当从天然环境中提取时，这些可以形成能够掺入细胞的水凝胶，并用作组织工程的支架。然而，打印具有受控结构和机械性能的细胞接种胶原蛋白生物墨水具有挑战性。基于胶原蛋白的水凝胶生物墨水受到其狭窄的可印刷性范围的限制，其中蛋白质结构、接种细胞活力和掺入的生物分子的生物活性都需要严格控制。此外，当这些胶原蛋白分子组装成水凝胶时，它们的纤维含量低，机械刚度和强度性能低，所有这些都影响了我们设计稳定分层结构的能力。为了克服这些挑战，我们开发了一种新的方法，通过我们的自动凝胶抽吸喷射技术来生物打印胶原蛋白结构。通过使用该过程，我们可以产生仿生的、致密的、组织样的胶原基质，其可以用作体外模型，并且作为硬组织和软组织的潜在再生的支架。该技术也是理想的生产功能化的支架通过纳入其他生物聚合物或生物活性玻璃。我们还将使用我们在实验室开发的低温溶胶-凝胶工艺路线来合成一系列新的硼酸盐基玻璃，并使致密的胶原蛋白生物墨水功能化。通过这一点，我们可以确定驱动组织再生的生化因素，并继续开发生物材料开发的新技术。因此，从这项发现资助计划中获得的知识将为许多领域做出重大贡献，如3D生物打印，生物制造和组织工程。它还将继续为学员提供丰富多样的环境，同时作为创新技术的平台。

Additive manufacturing and three-dimensional bioprinting technologies have recently generated much interest in developing biomaterials, such as in biofabricating tissue engineering scaffolds, medical devices, and in vitro tissue-like structures that model both healthy and diseased conditions, thus enabling high-throughput drug screening and diagnostic tools. 3D bioprinting relies on the layer-by-layer deposition of tissue specific cells incorporated into hydrogels (called bioinks) to form complex hierarchical structures that mimic the body's natural extracellular matrix. Therefore, the composition, 3D bioprintability, as well as resulting bioink structure and mechanical properties are all critical to success, and ideally these would mimic, as best as possible, the natural tissue extracellular matrix. The fibre-forming collagen type I molecule is the natural scaffolding material that exists in our body. It provides many key biological and mechanical properties to numerous tissues. When extracted from the native environment, these can form hydrogels that are able to incorporate cells and be used as scaffolds for tissue engineering. However, the printing of cell-seeded collagen-based bioinks with controlled structure and mechanical properties is challenging. Collagen-based hydrogel bioinks are restricted by their narrow printability range, where the protein structure, seeded cell viability, and bioactivity of incorporated biomolecules, all need to be tightly controlled. Also, when these collagen molecules assemble into hydrogels, they suffer from low fibrillar content and have low mechanical stiffness and strength properties, all impacting our ability to engineer stable hierarchical structures. In order to overcome these challenges, we have developed a novel approach to bioprint collagen structures through our automated gel aspiration-ejection technique. By using this process, we can generate biomimetic, dense, tissue-like collagenous matrices, which can be used as in vitro models, and as scaffolds for the potential regeneration of hard and soft tissues. The technique is also ideal for producing functionalized scaffolds by incorporating other biopolymers or bioactive glasses. We will also use our in-lab developed low temperature sol-gel processing route to synthesize a novel range of borate-based glasses and to functionalize the dense collagen bioinks. Through this, we can identify the biochemical factors that drive tissue regeneration, and to continue to develop novel technologies for biomaterials development. Therefore, the knowledge gained from this Discovery Grant Program will significantly contribute to a number of fields, such as 3D bioprinting, biofabrication and tissue engineering. It will also continue to provide a rich and diverse environment for its trainees, while serving as a platform for innovative technologies.