Mori Silkworm Cocoon Research Articles

Chemical, Thermal, Time, and Enzymatic Stability of Silk Materials with Silk I Structure.

The crystalline structure of silk fibroin Silk I is generally considered to be a metastable structure; however, there is no definite conclusion under what circumstances this crystalline structure is stable or the crystal form will change. In this study, silk fibroin solution was prepared from B. Mori silkworm cocoons, and a combined method of freeze-crystallization and freeze-drying at different temperatures was used to obtain stable Silk I crystalline material and uncrystallized silk material, respectively. Different concentrations of methanol and ethanol were used to soak the two materials with different time periods to investigate the effect of immersion treatments on the crystalline structure of silk fibroin materials. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman scattering spectroscopy (Raman), Scanning electron microscope (SEM), and Thermogravimetric analysis (TGA) were used to characterize the structure of silk fibroin before and after the treatments. The results showed that, after immersion treatments, uncrystallized silk fibroin material with random coil structure was transformed into Silk II crystal structure, while the silk material with dominated Silk I crystal structure showed good long-term stability without obvious transition to Silk II crystal structure. α-chymotrypsin biodegradation study showed that the crystalline structure of silk fibroin Silk I materials is enzymatically degradable with a much lower rate compared to uncrystallized silk materials. The crystalline structure of Silk I materials demonstrate a good long-term stability, endurance to alcohol sterilization without structural changes, and can be applied to many emerging fields, such as biomedical materials, sustainable materials, and biosensors.

The Analysis and Comparison of the Needle-puncture Property of Four Types of Silkworm Cocoons

Silkworm cocoons display outstanding properties in many aspects, such as thermal protection, biocompatibility and mechanical resistance and so on. In this paper, we focus on the puncture properties without detailed exploration of four types of cocoons (three domesticated cocoon and Eri silkworm). Different sections, end and middle, as well as different directions, puncturing from inner and outer surface, of four types of aforementioned cocoons were systematically analyzed and compared. The results of present research show that the middle section exhibits a relatively greater needle-puncture resistance compare with end section for three B. mori silkworm cocoons. With regard to different puncture directions, from external and internal surface, puncturing from internal surface exhibits a relatively higher needle-puncture load as well as fracture displacement tendencies compared with needle-puncture performance from external surface no matter in middle or end sections. Combining physical parameter assessment, statistical analysis and needle-puncture performance, this research inspires a clear-cut frame to design a composite with high puncture resistance.