Stereolithography-assisted sodium alginate-collagen hydrogel scaffold with molded internal channels

Fabricating internal vascular networks within a hydrogel scaffold is essential for facilitating the supply of nutrients, oxygen, and metabolism exchange required by the encapsulated cells. The challenges in current hydrogel scaffold fabrication involve the difficulty of building adequate internal channels, poor scaffold geometry precision, and low cell viability caused by the fabrication process and polymer material properties. Stereolithography (SLA) stands out as a 3D printing technique distinguished by its superior production efficiency, advanced precision, and remarkable resolution in crafting intricate custom geometries. These attributes establish it as an innovative approach for templates in scaffold fabrication, potentially surpassing the fused deposition modeling (FDM)-based template strategy. Meanwhile, it exerts less shear stress on the cells compared to the direct bioprinting process. This novel strategy enables the fabrication of hydrogel vascular structure within the precision of 500 µm in both channel diameter and wall thickness. In this paper, various sodium alginate and collagen (SA-Col) composite hydrogels with varying collagen concentrations have been investigated to identify the optimal ratio for fabricating hydrogel scaffolds with channels.