Mimicking Design Scaffolds Based on Nonwoven Biological Materials of Silk Cocoon for Soft Tissue Engineering at the Bone Interfacial Area: Structure, Morphology, and Performance Evaluation Based on In Vitro Testing, and Identification of Applied Biomaterials.

Abstract

The malformation of soft tissue engineering at the bone interfacial area is a critical problem for surgery. Mimicking design scaffolds based on nonwoven biological materials were created for soft tissue engineering at the bone interfacial area. Silk cocoons were cut into small pieces before degradation by lysozyme at 0 (untreated), 1, 2, 3, and 4 weeks (Mimic-SC0, Mimic-SC1, Mimic-SC2, Mimic-SC3, and Mimic-SC4, respectively). The molecular structure of degraded silk cocoons was characterized using Fourier transform infrared spectroscopy and differential scanning calorimetry. The morphology was examined using scanning electron microscopy. Wettability was tested using the contact angle, while the mechanical properties were tested using the mode of tensile force. The silk cocoons were cultured with L929 fibroblasts and MC3T3-E1 osteoblast cells. Fibroblast response was tested with cell proliferation and attachment, H&E staining, and Masson staining. Osteoblast response was tested with cell proliferation and attachment, alkaline phosphatase (ALP) activity, and osteocalcin (OCN). Mimic-SC1, Mimic-SC2, Mimic-SC3, and Mimic-SC4 showed amide I mobility and low regular structural formation. All samples showed multilayered fibrous structures with dense inner and loose outer zones. Mimic-SC1, Mimic-SC2, Mimic-SC3, and Mimic-SC4 had fibers of smaller size than Mimic-SC0. Mimic-SC3 and Mimic-SC4 showed higher wettability than the others. Mimic-SC1, Mimic-SC2, Mimic-SC3, and Mimic-SC4 exhibited higher toughness and flexibility than Mimic-SC0. Mimic-SC1, Mimic-SC2, Mimic-SC3, and Mimic-SC4 exhibited better fibroblast cell adhesion along with higher proliferation than Mimic-SC0. All samples showed cell migration into the deeper layer on day 10. Mimic-SC4 had cell adhesion with continuous regular alignment and dense organization on its surface. Mimic-SC4 exhibited collagen accumulation connected to the layer of cell adhesion. Mimic-SC1, Mimic-SC2, Mimic-SC3, and Mimic-SC4 exhibited higher osteoblast proliferation, ALP activity, and OCN levels than Mimic-SC0. Our research deduced that Mimic-SC4 shows promise in soft tissue engineering at the bone interfacial area.