Injectable hierarchical micro/nanofibrous collagen-based scaffolds

Collagen exhibits an exceptional biocompatible performance that can be used in tissue regeneration applications. Therefore, it is widely used in various structural shapes, e.g., nanofibers and microscale struts in multi-layered structure. Here, we developed a unique hierarchical collagen structure consisting of spatially coiled microfibers and inter-laden nanofibers with collagen type-I by using a modified electrohydrodynamic-printing process. The hierarchical collagen scaffolds showed not only an outstanding mechanical flexibility and creep recovery, demonstrating good injectable property, but also excellent cellular activities compared to those of the controls (an electrospun collagen nanofibrous mat and a three-dimensionally printed collagen scaffold). To demonstrate its feasibility as an injectable scaffold, it was injected and deployed through micro-sized needles. An exceptional injectability was observed without any breakage of the initial pore geometry. Here, the bone marrow-derived mesenchymal stem cells were cultured on the collagen scaffold for 1 and 3 days. According to several cellular activities including cell-viability, the cultured cells were well protected for the injection process and exhibited excellent biocompatibilities as compared to those of the controls.