Introduction
Sericin is a hot water-soluble macromolecular globular protein. It represents a family of proteins having molecular mass of 10 to 310 kDa. Sericin
envelops the fibroin fibre with successive sticky layers that help in the
formation of cocoon. Sericin contributes about 20-30% of the total cocoon
weight. The sericin protein is made of 18 amino acids most of which have
strongly polar side groups such as hydroxyl, carboxyl and amino groups 1-3.
Figure 1: Composition of Silk
Filament
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Silk sericin, abundantly present in the silk processing waste water, can generate revenue for silk processing industry as a natural value
added material.
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During last decade, sericin has emerged as a biomaterial of
commercial value having diverse physiological properties such as antioxidant,
UV protection, moisture adsorption, antibacterial activity etc 4.
The cosmetics industry is using sericin in its moisturizing and skin care products since it inhibits the tyrosinase activity and promotes biosynthesis5.
Moreover, its high hydroxyl-amino acid content has high water-binding capacity
that keeps the skin moist. Masahiro et al.6 have reported that
consumption of sericin enhances bioavailability of Zn, Fe, Mg and Ca in rats
therefore it can be a valuable natural ingredient for food industry.
Some studies have indicated that sericin, exerts inhibitory
activity on ultra-violet radiation induced acute damage, posses the biological
activity of preventing cell death and promoting cellular growth after acute
serum deprivation 7. Moreover, sericin has also been found to be
useful as a degradable biomaterial, biomedical material and polymers for
forming articles, functional membranes, fibres and fabrics 4.
Use of sericin as a finishing agent for natural or man made
textiles enhances moisture absorption, antistatic properties, softness and
comfort 8. Filters made of polyamide or polyester fibres coated with
sericin have antioxidation and antimicrobial activity, suggesting their
potential use as indoor air filters to reduce free radicals and fungi or
bacteria contamination9. Sericin can be cross linked, copolymerized
or blended with other polymers to produce a new range of biodegradable
materials with improved properties 4.
Thus because of its varied properties, sericin can be used
as an additive in food, cosmetics, textiles and pharmaceutical products as indicated in Fig. 2.
Figure 2: Application of sericin in
various industries
