In the production of aerogel from the liquid silk gel in silk gland of fully grown larvae of domestic Bombyx mori silkworm, when the unfolding time of liquid silk gel in water at room temperature did not exceed 10 min, obtained aerogel showed hydration and could be dissolved into water by the water annealing at 50°C. On the other hand, when the unfolding time of liquid silk gel reached 4 hours, the water solubility of obtained aerogel was limited although the hydration behavior could be observed. Sericin and only limited fibroin fractions could be dissolved by the water annealing at 50°C. The difference in water solubility between the two type aerogels could be explained considering the molecular interactions between fibroin and sericin fractions. The interactions seems to be dissociated if the unfolding time of liquid silk gel in water at room temperature exceed a certain period.
Wide angle X-ray diffraction (WAXD) curves were measured on the divided portions of freeze-dried silk gland of fully grown larvae of domestic Bombyx mori silkworm, and the influence of sericin fractions on the crystal modification of fibroin was investigated. It was found that fibroin molecules could be modified to crystal precursor of Silk II when sericin P was secreted, and then, turned to crystal precursor of Silk I when sericin M was secreted.
