Formation of Nickel(II) Silk Fibroin (Bombyx mori) Complexes and their Secondary Structures

Abstract

The preparation of Ni(II) silk fibroin (Bombyx mori) complex was carried out under various conditions of pH and TNI2+/THL (molar ratio of reacting species) in an aqueous solution at 25° C, and the secondary structure of the products was investigated. In an aqueous fibroin solution, the galation was observed in the presence of Ni (II) ion and the pH range below 9. The infrared and X-ray diffraction pattern of these gels showed that the crystals formed in the gel are cross / structure. Furthermore, the Ni (II) (N4) planar chelated structure of inner polymer molecular complex is formed in the pH range above 10. The viscosities of an aqueous silk fibroin solution decrease with increasing amount of nickel biuret complex. The films obtained from an aqueous silk fibroin solution gave X-ray pattern of the random coil structure.