α-Tricalcium phosphate cement reinforced with silk fibroin: A high strength biomimetic bone cement with chloride-substituted hydroxyapatite

In the past decades, bone defects have become an increasing factor in the development of disability in patients, impacting their quality of life. Large bone defects have minor chances to self-repair, requiring surgical inter-vention. Therefore, & alpha;-TCP-based cements are rigorously studied for the development of bone filling and replacement applications due to the possibility of application in minimally invasive procedures. However, & alpha;-TCP-based cements do not present adequate mechanical properties for most orthopedic applications. The aim of this study is to develop a biomimetic & alpha;-TCP cement reinforced with 0.250-1.000 wt% of silk fibroin using non-dialyzed SF solutions. Samples with SF additions higher than 0.250 wt% presented complete transformation of the & alpha;-TCP to a biphasic CDHA/HAp-Cl material, which could enhance the osteoconductivity of the material. Samples reinforced with concentrations of 0.500 wt% SF showed an increase of 450% of the fracture toughness and 182% of the compressive strength of the control sample, even with 31.09% porosity, which demonstrates good coupling between the SF and the CPs. All samples reinforced with SF showed a microstructure with smaller needle-like crystals when compared to the control sample, which possibly contributed to the material's rein-forcement. Moreover, the composition of reinforced samples did not affect the cytotoxicity of the CPCs and enhanced the cell viability presented by the CPC without SF addition. Hence, biomimetic CPCs with mechanical reinforcement through the addition of SF were successfully obtained through the developed methodology, with the potential to be further evaluated as a suitable material for bone regeneration.