Influence of collagen fibril alignment in collagen scaffolds mineralization

• Autor(a) principal: Roberto, Nuno Gonçalo Rosa
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/117490
• topic: hydrogels; scaffolds; collagen; suspension printing; suspended electrowriting; bone regeneration; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

Bone extracellular matrix (ECM) gives bone its unique mechanical properties, thus being important in bone tissue engineering to mimic its native composition and microstructure. The main component in bone ECM is Type-I collagen, which works as a scaffold for bone cell attachment and mineral deposition. There are two locations where mineralization takes place: the intrafibrillar and interfibrillar spaces of collagen fibrils. Several theories try to explain mineral formation in bone tissue. However, none of them was proven right, and so, the mechanism for mineralization facilitated by the collagen lattice is still unknown. This way, it is essential to study such a mechanism and develop bone tissue engineering approaches to mimic bone ECM. In this work, we hypothesized that collagen fibrils alignment would promote scaffolds mineralization. To prove it, we 3D printed fibrillar collagen hydrogels scaffolds using the suspension 3D printing technique, in which a gelatin slurry was used as a suspension bath. First, an optimization of the printing process was performed. Then scaffolds were printed, choosing the finest (123 ± 25 µm) and largest fiber diameter (215 ± 66 µm) obtained. Fiber diameter size was proven to affect the collagen fiber alignment inside the scaffolds and, consequently, affect mineral precipitation. The smallest fiber diameter scaffold showed signs of mineralization after one day inside a mineralization solution. In contrast, the largest fiber scaffold only presented mineralization signs after three days of submersion. Moreover, suspended electrowriting was introduced in this dissertation, obtaining a 40 µm jet diameter inside a castor oil bath, proving to be a promising additive manufacturing technology to achieve higher resolution constructs when 3D printing hydrogels.