Production and characterizations of tubes from hornet (Vespa) silk

Abstract

We have developed a simple technique to fabricate tubes of hornet (Vespa) silk protein. In this technique, a column of homogeneous hornet silk hydrogel uniformly forms around a straight wire core that serves as an inert scaffold. The tube is then thoroughly dried. During drying, the hydrogel was isotropically contracted toward the core wire. Finally, the wire is pulled out of the dried gel and the gel tubes are complete. Examination showed that the inner and outer diameters of the gel tubes were uniform and that the inner and outer surfaces were smooth. The silk content in the hydrogel, which can be controlled by adjusting the concentration of silk in the solution before gelation, affected the diameter and wall thicknesses of the tubes as well as their physical properties, including tensile and compression strength. When the gel tube was rehydrated, the tube showed some degree of swelling and flexibility; however, it did not return to the original hydrogel form. Under uniaxial tension, the rehydrated tube could show uniform twofold or threefold stretching. Moreover, no conformational change and no thermal degradation occurred in the dried hornet silk gel tube during incubation at 180°C for 40min. This indicates that the dried hornet silk gel tube can withstand dry heat sterilization (180°C for 30min), which makes it suitable for use in medical applications.