Physicochemical Characterization of a Silk Fibroin Film Fabricated from an <i>Antheraea frithi</i> Moore Cocoon for Potential Biomaterial Application

Silk fibroin has numerous biological applications, including wound healing, bone regeneration, corneal regeneration, and tissue engineering. There have been several reports on the fabrication of silk fibroin films using mulberry (<i>Bombyx mori</i>) and other wild nonmulberry silkworms. In our present study, we employed the natural cocoon of <i>Antheraea frithi</i> Moore, a nonmulberry silkworm, to generate a silk fibroin film through a series of stages including demineralization, degumming, dissolution, and casting of the regenerated silk fibroin solution. The X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) results revealed that the fabricated silk fibroin film exhibits β sheet, α helix, and random coil structures. The thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) data revealed that the silk materials, ranging from raw cocoon shell to silk fibroin film, exhibited 5-6 endothermic peaks between 50 and 380 °C, indicating association of water loss, protein structural rearrangement, and thermal degradation during thermal treatment. The trace elemental studies of the possible presence of 15 different elements from ppm to ppb levels were performed. This study revealed that raw cocoon shells are free from toxic heavy metals, such as Hg or Pb. The presence of Ca, Na, and K as a major element is found in the raw cocoon shell. These findings are crucial for the potential application of the fabricated silk fibroin film prepared from the cocoon of <i>A. frithi</i> Moore as a biomaterial for biomedical application.