Research on silk fibroin composite materials for wet environment applications

Silk fibroin material has good mechanical properties and excellent biocompatibility as a natural biomaterial with broad application prospects. However, by applying regenerated silk fibroin in biomaterials with high mechanical strength requirements, such as bone materials, there are problems, such as insufficient mechanical properties and a significant decline in mechanical properties in the wet state. In this report, a silk fibroin composite that maintains high strength in the wet state was prepared by adding nano-SiO2 as a nano-strengthening filler to the silk protein material and employing an epoxy-based silane coupling agent KH560 as an interfacial reinforcing agent. The results showed that the dry compressive strength of the composite material was substantially increased compared with that of the pure silk protein material; the wet compressive strength was significantly increased compared with that of the pure silk fibroin material, and the decrease of the mechanical properties in the wet state was low. The cytotoxicity test results of the composites showed that the materials were not cytotoxic. Rat bone marrow mesenchymal stem cells were cultured on the surface of the composites, and the results indicated that the composites could support the proliferation of bone marrow mesenchymal stem cells. The silk fibroin nanocomposites developed in this work can be applied as bone repair materials. [Display omitted] •When the addition of nano-SiO2 catalyzed by L-lysine is only 5% of the amount of silk fibroin, it forms a large number of hydrogen bonds, which boosts the compressive strength of the silk fibroin material in the dry state.•The addition of KH560 achieved the reinforcing and toughening effect of SiO2/SF composites and improved the mechanical properties in the wet state, which reached the mechanical properties of the thigh bone in the wet state.•The high mechanical properties of composites in the wet state, with a wet compression strength of 67 MPa, low cytotoxicity, and the ability of bone marrow mesenchymal stromal cells to grow and increase on the material, which can meet the needs of bone tissue repair.