Free-standing collagen fiber scaffolds for soft tissue engineering

Abstract text (incl. figure legends and references)

Introduction: Free-standing scaffolds play a pivotal role in tissue engineering as they promote cell migration due to enhanced nutrient diffusion in comparison to immobilized scaffolds. However, current methods to prepare free-standing scaffolds are often limited to the production of hydrogels, e.g., from fibrin and collagen. Hence, we introduced a new method to assemble collagen into nanofibers that spontaneously detach from the substrate.

Methods: Flexible alumina textiles with a tricot knit structure (Zircar Zirconia Inc., USA) were modified with (3-Aminopropyl)triethoxysilane. Collagen nanofibers were assembled on the textiles by adding PBS solution and crosslinked with glutaraldehyde^1,2. The morphology of detached collagen was analyzed with scanning electron microscopy, and the mechanical properties were measured by tensile testing.

Results: Crosslinked collagen scaffolds spontaneously rolled up with the modified Al₂O₃ textiles (Fig. 1) and subsequently detached with an inner diameter of 2-4 mm. Mechanical testing of wet collagen scaffolds yielded a mean tensile strength of 3.5 ± 1.9 MPa, 41.0 ± 20.8 MPa for the Young"s modulus and 8.1 ± 3.7% for the elongation at break. Unmodified Al₂O₃ textiles did not induce any roll-up, as collagen failed to assemble into fibers. Blends of collagen and chitosan formed fibrous composites on silanized Al₂O₃ textiles, while fibrinogen nanofibers or blends of collagen and elastin did not. These observations suggest that textile porosity and protein charge contribute to scaffold roll-up.

Conclusion: We introduced a simple method to prepare free-standing collagen nanofibers on Al₂O₃ textiles. These self-supporting scaffolds can allow cell cultivation on both sides and could therefore serve, for example, as in vitro models of the basement membrane or skin.

References

1 Dutta, D. et al. ACS Appl. Bio Mater. 2021

2 Suter, N. et al. Biofabrication 2021

Fig. 1: Rolled-up Al₂O₃ textile coated with nanofibrous collagen