Sericin

Sericin is a family of water-soluble glycoproteins produced by the silk glands of silkworms, most notably Bombyx mori. It coats the fibroin fibers that compose raw silk and acts as a natural adhesive that binds the filaments together. In raw silk, sericin typically accounts for a substantial portion of the fiber’s weight, and it is usually removed in a standard degumming process to yield a soft, lustrous fibroin fiber. The sericin-rich material can be processed separately for external and biomedical uses.

Sericin molecules are rich in polar amino acids, especially serine, glycine, and alanine, giving them hydrophilic character. They are soluble in hot water and can be extracted by mild alkaline or hot-water methods. The proteins can form gels, films, or powders and are processed into solutions, nanoparticles, or incorporated into biomaterials. Molecular weight distribution and extraction method influence its functional properties.

Applications for sericin span textiles, cosmetics, and biomedicine. In textiles, sericin is often viewed as a byproduct of degumming, yet recovered sericin extracts are used in value-added products. In cosmetics, sericin is marketed as a moisturizing and film-forming ingredient. In biomedicine and tissue engineering, sericin-based materials are explored for wound dressings, cell culture substrates, hydrogels and drug delivery systems due to biocompatibility and biodegradability, with ongoing research into optimization and safety.

Safety and regulation: Sericin is generally regarded as safe for cosmetic and biomedical applications, though rare allergic reactions can occur. Environmental considerations include recycling sericin from silk-processing streams to reduce waste.