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引起了人们对开发生物材料的极大兴趣，例如生物制造组织工程支架、医疗设备和体外组织样结构，这些结构可以模拟健康和疾病状况，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定细胞逐层沉积到水凝胶（称为生物墨水）中，形成复杂的分层结构，模仿人体的天然细胞外基质。因此，合成物、3D生物打印的可移植性，以及由此产生的生物链接结构和机械性能都是成功的关键，理想情况下，这些将尽可能地模仿自然组织细胞外基质。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和机械特性。当从自然环境中提取时，它们可以形成能够结合细胞的水凝胶，并用作组织工程的支架。然而，打印具有可控结构和机械性能的细胞种子胶原基生物墨水是具有挑战性的。基于胶原蛋白的水凝胶生物墨水受到其狭窄的打印范围的限制，其中蛋白质结构，种子细胞活力和纳入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，它们的纤维含量很低，机械刚度和强度也很低，这些都影响了我们设计稳定层次结构的能力。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。通过这一过程，我们可以生成仿生的、致密的、组织样的胶原基质，它可以用作体外模型，也可以作为硬组织和软组织再生的潜在支架。该技术也是通过结合其他生物聚合物或生物活性玻璃来生产功能化支架的理想技术。我们还将使用我们在实验室开发的低温溶胶-凝胶加工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对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.