X‐ray photoelectron spectroscopic and Raman analysis of silk fibroin–Cu(II) films

Abstract There is evidence to suggest that Cu(II) is involved in the natural spinning process of a silkworm helping to convert the concentrated silk fibroin (SF) solution (or dope) into tough insoluble threads. To investigate the interaction between SF and Cu(II), a series of regenerated SF (RSF) films with different mass ratios of Cu(II) to SF were prepared. X‐ray photoelectron spectroscopy (XPS) was employed to study the chemical interaction between Cu(II) and SF in these Cu(II)–RSF films. A significant change in the binding energy of Cu 2p 3/2 demonstrated that the chemical state of Cu(II) in the Cu(II)–RSF films was affected by the interaction between Cu(II) and SF. Moreover, chemical shifts of N 1s and O 1s of SF were also detected, implying that Cu(II) may coordinate with both N and O atoms in the SF. In addition, Raman spectra of the same series of Cu(II)–RSF films recorded the conformation transition of SF that may occur by the coordination of Cu(II) and SF macromolecular chains. © 2006 Wiley Periodicals, Inc. Biopolymers 82: 144–151, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com