Tunable Blended Collagen I/II and Collagen I/III Hydrogels as Tissue Mimics.

Collagen (Col) is commonly used as a natural biomaterial for biomedical applications. Although Col I is the most prevalent col type employed, many collagen types work together in vivo to confer function and biological activity. Thus, blending collagen types can better recapitulate many native environments. This work investigates how hydrogel properties can be tuned through blending collagen types (col I/II and col I/III) and by varying polymerization temperatures. Col I/II results in poorly developed fibril networks, which softened the gels, especially at lower polymerization temperatures. Conversely, col I/III hydrogels exhibit well-connected fibril networks with localized areas of fine fibrils and result in stiffer hydrogels. A decreased molecular mass recovery rate is observed in blended hydrogels. The altered fibril morphologies, mechanical properties, and biological signals of the blended gels can be leveraged to alter cell responses and can be used as models for different tissue types (e.g., healthy vs fibrotic tissue). Furthermore, the biomimetic hydrogel properties are a tool that can be used to modulate the transport of drugs, nutrients, and wastes in tissue engineering applications.