Silk is primarily composed of two core components: fibroin and sericin.
Fibroin (70%–80%): As the main component of silk, it consists of 18 amino acids, among which glycine, alanine, and serine are the most abundant. Its molecular structure is chain-like, forming regular β-sheet crystalline regions and amorphous regions connected by hydrogen bonds, endowing silk with softness, toughness, and moisture absorption properties.
Core Functions
Mechanical Support: The dense molecular arrangement of the β-sheet structure grants fibroin high strength and toughness, with an elongation rate of 15%–25%, making silk resistant to breakage and stretching.
Biocompatibility: Non-toxic and non-irritating, it can be degraded and absorbed by the human body, and is widely used in biomedical materials.
Moisture Absorption and Breathability: Tiny pores exist between molecular chains, which can absorb moisture from the air and quickly expel dampness, keeping fabrics dry.
Sericin (20%–30%): A water-soluble globular protein that wraps around the outside of fibroin. It has strong viscosity and functions to bond individual silk filaments to form the cocoon layer. Sericin is also rich in amino acids, especially hydrophilic ones.
Core Functions
Bonding and Protection: During the silkworm's spinning process, sericin binds and wraps two fibroin filaments into a complete silk thread, while protecting the internal fibroin from damage by external microorganisms.
Skin-Care Efficacy: It has excellent moisturizing and film-forming properties, which can form a protective film on the skin surface to lock in moisture and improve skin dryness. Meanwhile, it can promote the proliferation of skin cells, making it a common ingredient in cosmetic raw materials.
Antibacterial Properties: Tyrosine in sericin has certain antibacterial activity, which can inhibit the growth of common bacteria such as Escherichia coli and Staphylococcus aureus.
Main Applications of Silk
Traditional Textile Industry: The most important application field of silk, used for manufacturing silk fabrics, high-grade apparel, and home textile products. Among them, mulberry silk is of the highest quality, mostly used in high-end clothing and luxury goods.
Food Industry: The core lies in utilizing the nutritional characteristics and functional activity of its hydrolyzate-silk protein peptides. It has been applied in health food, functional food additives, special dietary products, etc., and can supplement amino acids required by the human body.
Beauty and Skincare Industry: Silk can be directly used in skincare products such as silk facial masks, silk facial cleansing towels, and silk protein essence.
In terms of raw materials, fibroin and sericin can be hydrolyzed into small-molecular peptides and added to creams, lotions, shampoos, etc., to enhance moisturizing and repairing effects.
Biomedical Industry: Silk can serve as medical consumables, mainly including absorbable silk sutures, wound dressings, artificial corneal scaffolds, and bone tissue repair materials. Additionally, the porous structure of fibroin can be used to fabricate sustained-release drug carriers, achieving targeted and long-acting drug release.