No abstract

There is an enormous demand for bone graft biomaterials to treat developmental and acquired bony defects arising from infections, trauma, tumor, and other conditions. Polycaprolactone (PCL) has been extensively utilized for bone tissue engineering but limited cellular interaction and tissue integration are the primary concerns. PCL-based composites with different biomaterials have been attempted to improve the mechanical and biological response. Interestingly, a few studies have tried to blend PCL with aqueous silk fibroin solution, but the structures prepared with the blend were mechanically weak due to phase mismatch. As a result, silk microparticle-based PCL composites have been prepared, but the microfibers-reinforced composites could be superior to them due to significant fiber-matrix interaction. This study aims at developing a unique composite by incorporating 100-150 μm long (aspect ratio; 8:1-5:1) silk-fibroin microfibers into the PCL matrix for superior biological and mechanical properties. Two silk variants were used, that is, Bombyx mori and a wild variant, Antheraea mylitta, reported to have cell recognizable Arginine-Glycine-Aspartic acid (RGD) sequences. A. mylitta silk fibroin microfibers were produced, and composites were made with PCL for the first time. The morphological, tensile, thermal, biodegradation, and biological properties of the composites were evaluated. Importantly, we tried to optimize the silk concentration within the composite to strike a balance among the cellular response, biodegradation, and mechanical strength of the composites. The results indicate that the PCL-silk fibroin microfiber composite could be an efficient biomaterial for bone tissue engineering.

No abstract

Regenerative biomaterials play a crucial role in the success of maxillofacial reconstructive procedures. Yet today, limited options are available when choosing polymeric biomaterials to treat critical size bony defects. Further, there is a requirement for 3D printable regenerative biomaterials to fabricate customized structures confined to the defect site. We present here a 3D printable composite formulation consisting of polycaprolactone (PCL) and silk fibroin microfibers and have established a robust protocol for fabricating customized 3D structures of complex geometry with the composite. The 3D printed composite scaffolds demonstrated higher compressive modulus than 3D printed scaffolds of PCL alone. Furthermore, the compressive modulus of PCL−Antheraea mylitta (AM) silk scaffolds is higher than that of the PCL− Bombyx mori (BM) silk scaffolds at their respective ratios. Compressive modulus of PCL−25AM silk scaffolds (73.4 MPa) is higher than that of PCL− 25BM silk scaffolds (65.1 MPa). Compressive modulus of PCL−40AM silk scaffolds (106.1 MPa) is higher than that of PCL−40BM silk scaffolds (77.7 MPa). Moreover, we have isolated, characterized, and integrated human gingival mesenchymal stem cells (hGMSCs), an effective autologous cell source, onto the 3D printed scaffolds to evaluate their bone regeneration potential. The results demonstrated that PCL−silk microfiber composite scaffolds of Antheraea mylitta origin showed much higher bioactivity than the Bombyx mori ones because of arginine−glycine−aspartic acid (RGD) sequences present in the Antheraea mylitta silk fibroin protein favoring cell attachment and proliferation. By day 14, the metabolic activity of hGMSCs was highest in PCL−40AM (4.5 times higher than that at day 1). In addition, to show the translational potential of this work, we have fabricated a patient defectspecific model (mandible) using the CT scan obtained by the micro-CT imaging to understand the printability of the composite for fabricating complex structures to restore maxillofacial bony defects with precision when applied in a clinical scenario.