Natural protective glue protein, sericin bioengineered by silkworms: Potential for biomedical and biotechnological applications

Silk proteins consist of a fibrous core protein, fibroin, and glue proteins called sericins, which envelop the fibroin fiber with successive sticky layers that help in the formation of a cocoon by cementing together the silk fibers. This system is essentially a protein-fiber composite system, with fibers of the high-molecular-weight fibroin proteins surrounded by the glue-like continuous phase of the sericin. In mulberry silk produced by Bombyx mori, Ser1 and Ser2 are the two major genes encoding for sericin. Ser1 is the most abundant silk sericin of B. mori and consists of repeats of a 38-amino acid motif that contributes towards the hydrophilicity of sericin. The protein has partially been characterized from non-mulberry silkworms like the tropical tasar Antheraea mylitta, and studied for various potential applications because of its unique biochemical and biophysical properties. These applications include the skincare and food industries, as coating material for biomedical applications like anticoagulants, in anticancer drugs, for drug delivery, and in tissue engineering. Sericin promotes proliferation of cells when used as a constituent of cell culture in serum-free media. Sericin also supports cell adhesion and proliferation when used in pure form and/or blended in matrices. Sericin films, 3D scaffolds, nanoparticles, composites, conjugated drugs, and recombinant sericins offer potential future options for these needs.