Studies Show that Silk Fibroin Material May be Suitable for Interlocking Nails

Researchers from Chiang Mai University in Thailand published a paper, “Preparation and characterization of silk fibroin from four different species
of Thai-local silk cocoon for Bone implanted applications,” regarding the use of PLA reinforced with locally-sourced silk fibroin to 3D print a biocomposite interlocking nail to treat fractures.

Silk is made of 75% biocompatible fibroin, a  material with multiple medical applications. Previous studies have shown that fibroin has good biological and mechanical properties such as biocompatibility, biodegradability, water permeability, non-cytotoxicity and the strength and
resiliency of silk fibers. Silk fibers have a tensile strength of 740 MPa, while collagen and polylactic acid have an ultimate tensile strength only 0.9 to 7.4 and 28 to 50 MPa, respectively. Thus, researchers chose silk fibroin as a reinforcing material for polylactic acid (PLA) to create the biocomposite filament for a 3D-printed interlocking nail.

After extracting the fibroin from four species of local silk cocoons, each were examined with Scanning Electron Microscopy, Energy Dispersive X-ray and Fourier Transform Infrared Spectroscopy. Further, biological tests studied cell viability and cytotoxicity with human fetal osteoblast cells.

Results indicate that all of the cocoon species presented non-cytotoxicity and interconnected pores, and were suitable for use in humans.

Silk fibroin will be used to reinforce PLA-based interlocking nails which will be fabricated by 3D printing. Silk fibroin should provide a satisfactory biological environment to accelerate bone healing by providing a good surface for cell adhesion, migration and proliferation. Further, silk fibroin and PLA can be degraded via biologically enzymes, eliminating the need for another procedure to remove the implant.

In future research, the biocomposite filament for 3D printing from silk fibroin-reinforced PLA will be tested and observed for cell proliferation ability, mechanical properties and printing morphology.

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