Dissolution of hornet silk in aqueous solution of calcium chloride

Abstract

Aqueous solution of calcium chloride (CaCl₂) is a promising solvent for biomaterial like silk fibroin, thereby offering potential application in industrial purposes. We observed that the silk, produced by larvae of hornets (Vespa), dissolved in an aqueous solution of CaCl₂ in the concentration range of 3-6 M. The solubility of hornet silk was the maximum when CaCl₂ concentration was 4.5 M. The rate of dissolution of the hornet silk in the aqueous solution of CaCl₂ was sensitive to temperature. The hornet silk was found to dissolve in 4.5 M CaCl₂ solution even at 20°C. Such high solubility of the hornet silk in the aqueous solution of CaCl₂ could be attributed to the low content of β-sheet structure. The silk dissolved in the aqueous solution of CaCl₂ within 1 h when the temperature was between 40 and 80°C, and less protein degradation occurred under the aforementioned condition.