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Tissue engineering aims to develop materials that help the body repair damaged tissues. Collagen is attractive for this purpose because it is a major component of the extracellular matrix, but conventional collagen hydrogels are mechanically weak, while dense collagen is more difficult to process and shape. This thesis investigated how collagen could be engineered into stable, printable and biologically accessible scaffolds.

Study I examined three-dimensional printing of conventional collagen using a support-bath technique. The method enabled controlled scaffold architecture, but the resulting collagen remained mechanically soft. The study showed that geometry could be imposed on collagen, while also revealing the need for greater structural function within the material itself.

Study II therefore focused on developing a dense collagen–silica hybrid, DCSi. A concentrated acidic collagen precursor containing hydrolyzed silanes remained processable before fabrication and was subsequently matured in alkaline borate. The maturation environment strongly influenced collagen organization, silica distribution and mechanical behavior. Borate produced a dense fibrillar collagen structure with finely distributed silica and substantially improved structural stability. DCSi could also be printed into multilayer structures when extrusion and stabilization were controlled together. Importantly, cells colonized the material in vitro, while host cells and blood vessels entered the scaffold after implantation.

Study III adapted DCSi for bone repair by introducing a calcium-phosphate mineral phase. Mineralized DCSi retained its collagen-rich structure and flexibility while providing a bone-specific inorganic component. After implantation in a rat femoral defect, mineralized DCSi produced more new bone than non-mineralized DCSi after six weeks.

Study IV examined DCSi as a printed patch for uterine tissue repair. The patches were designed as thin and flexible structures and were evaluated with or without mesenchymal stromal cells. Both supported tissue ingrowth and vascularization, while the cell-free patches showed more consistent structural regeneration under the conditions tested.

Together, these studies show that dense collagen can be engineered into a versatile scaffold platform by controlling how structure develops during processing. This provides a route towards collagen-based materials that are not only biologically relevant, but also structurally functional, manufacturable and adaptable to different regenerative applications.