Comparison of structures of luminescent silkworm silk prepared by feeding and dyeing

Silkworm silk is among the most widely used natural fibres for textile and biomedical applications owing to its extraordinary mechanical properties and superior biocompatibility. In this paper, we reported a direct procedure in producing intrinsically luminescent silk by feeding silkworms with Rhodamine B (RhB). We demonstrated that the amount of RhB in fibroin was much more than that in sericin for those silk fibres prepared by feeding (FM-silk). RhB was further successfully introduced into fibroin via dyeing (DM-silk). DM-silk has a bit higher RhB concentration at equilibrium. On the other hand, RhB in FM-silk exhibit better stability arising from hydrogen bonds with fibroin as indicated by FTIR.