Light-based 3D bioprinting of bone tissue scaffolds with tunable mechanical properties and architecture from photocurable silk fibroin.

Three-dimensional (3D) bioprinting based on digital light processing (DLP) offers unique opportunities to prepare scaffolds that mimic the architecture and biomechanical properties of human tissues. Limited availability of biocompatible and biodegradable bioinks amenable for DLP-bioprinting is an impediment in this field. This study presents a bioink prepared from silk fibroin (SF) tailored for DLP bioprinting. Photocurable methacrylated-SF (SF-MA) was synthesized with 67.3% of methacrylation. Physical characterization of rheological and mechanical properties revealed that the 3D printed hydrogels of SF-MA (spanning from 10 to 25 wt%) exhibit bone tissue-like viscoelastic behavior and compressive modulus ranging from ≈12 kPa to ≈96 kPa. The gels exhibited favorable degradation (≈48 to 91% in 21 days). This SF-MA bioink afforded the printing of complex structures, with high precision. Pre-osteoblasts were successfully encapsulated in 3D bioprinted SF-MA hydrogels with high viability. 15% SF-MA DLP bioprinted hydrogels efficiently supported cell proliferation with favorable cell morphology and cytoskeletal organization. A progressive increase in cell-mediated calcium deposition up to 14 days confirmed the ability of the gels to drive osteogenesis, which was further augmented by soluble induction factors. This work demonstrates the potential of silk fibroin-derived bioinks for DLP-based 3D bioprinting of scaffolds for tissue engineering.