Silk fibroin microfiber‐reinforced polycaprolactone composites with enhanced biodegradation and biological characteristics

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.

Three-Dimensional Printing of Customized Scaffolds with Polycaprolactone–Silk Fibroin Composites and Integration of Gingival Tissue-Derived Stem Cells for Personalized Bone Therapy

“…Briefly, in our previous study, we obtained long silk fibroin microfibers (the length and width of these long silk fibroin microfibers were 106 ± 57 μm and 13 ± 3 μm for B mori and 138 ± 96 μm and 28 ± 7 μm for A mylitta , respectively), and we prepared 25%, 40%, and 50% silk with PCL composites; 40% silk with PCL of both B mori and A mylitta silk displayed good bioactivity and tensile strength. We observed that the addition of greater than 40% silk into the PCL matrix results in a reduction in the mechanical strength of the composite . But, we observed nozzle obstruction due to longer fibers and could not 3D print the PCL–silk composites with long silk fibroin microfibers.…”

“…The A. mylitta and B. mori cocoons were procured from the Regional Sericultural Research Station and Basic Seed Multiplication and Training Centre, Central Silk Board, Telangana. The 3D printable composite formulations of PCL and silk fibroin microfibers were prepared following our earlier published protocol . Briefly, small pieces of silk cocoons were boiled in 0.02 M sodium carbonate (Sigma-Aldrich) for two sequential cycles for 15 min each for B. mori and 30 min each for A. mylitta silk and then underwent thorough washing with deionized water to eliminate the sericin remnants.…”

“…The 3D printable composite formulations of PCL and silk fibroin microfibers were prepared following our earlier published protocol. 9 Briefly, small pieces of silk cocoons were boiled in 0.02 M sodium carbonate (Sigma-Aldrich) for two sequential cycles for 15 min each for B. mori and 30 min each for A. mylitta silk and then underwent thorough washing with deionized water to eliminate the sericin remnants. The acquired silk fibroin was dried in hot air at 40− 50 °C for 5−6 h and utilized for hydrolysis in sodium hydroxide.…”

“…We observed that the addition of greater than 40% silk into the PCL matrix results in a reduction in the mechanical strength of the composite. 9 sodium hydroxide, increasing the reaction time, dialyzing to neutralize the pH, and freeze-drying to obtain the short silk fibroin microfibers, and two compositions, 25% and 40%, were selected.…”

Recent Developments of Silk-Based Scaffolds for Tissue Engineering and Regenerative Medicine Applications: A Special Focus on the Advancement of 3D Printing

“…Due to the presence of disulfide linkage, the heavy (H) and light (L) chains are connected in B. mori ’s silk fibroin. Moreover, 25 kDa of glycoprotein (P25) is also conjugated with these chains in a non-covalent manner [ 22 ]. The hydrophobic domains of H chains can form anti-parallel sheets and contain Gly-X (X being Ala, Ser, Thr, or Val) repeats.…”