Super-strong and uniform fluorescent composite silk from trace AIE nanoparticle feeding

Fluorescent silk fibroin materials have wide applications in tissue engineering and bioassay system, but the inhomogeneity of fluorescence and high amount of additive hinder their development. In this study, we reported a super-strong composite silk with excellent blue fluorescence intensity and uniformity by feeding silkworm trace amount of hexaphenylsilole (HPS) (0.0012 parts per thousand in the diet), an important aggregation-induced emission (AIE) molecule. The incorporation of HPS nanoparticles in silk altered the second structures of silk fibroin, reduced crystallinity and crystallite size and induced orientation of crystalline region. In addition, the obtained composite silk exhibited strong mechanical properties with breaking elongation of 11.9 +/- 1.7% and breaking strength of 503.0 +/- 44.4 MPa, improvement of 17.8% and 54.0%, respectively, in comparison with regular silk. These superstrong and uniform fluorescent silks may pave a route to prevent the quenching effect of conventional fluorescent silk fibroin materials and be potentially applied in biomedical field.