Azide-Incorporated Clickable Silk Fibroin Materials with the Ability to Photopattern

Incorporation of unnatural amino acids (UAAs) bearing bioorthogonal reactive groups into proteins could be a powerful tool for developing novel protein-based biomaterials with innovative and controlled performance. Bombyx mori silk fibroin is one of naturally derived protein materials extensively studied for biomaterials development due to its mechanical strength and biocompatibility. We recently reported the in vivo incorporation of UAAs, 4-substituted analogues of phenylalanine including 4-azidophenylalanine (AzPhe), into silk fibroin by expanding the repertoire of amino acids for protein biosynthesis in silk glands of B. mori using transgenic techniques. We demonstrated that azide groups in AzPhe incorporated into silk fibroin can be selectively modified by bioorthogonal azide–alkyne cycloaddition reactions (click chemistry). However, the incorporation of AzPhe into silk fibroin required a special feeding condition, which led to the limited production of silk fibroin. Here we report more efficient prod...