Sericin protein

Sericin biopolymer, an amorphous glue-like substance, is made up of 18 amino acids most of which 70% have a polar terminal functional group, such as -OH, -COOH, and -NH2 groups, which are responsible for its solubility as well as water absorption and desorption [72, 143]. Biocompatibility, blodegradablllty, excellent antimicrobial activity, resistance to UV radiation, and moisture absorption ability inherent properties along with its availability have facilitated its potential applications in different fields, including textiles [72, 77,143]. 

Rajendran et al. [118] have studied antimicrobial properties of cotton fabric coated with extracted sericin, using ice cold ethanol, by pad-dry-cure method. They found that the serlcln-coated fabric showed an efficient bactericidal activity against G+ve [5. aureus) and G-ve [ coli) bacteria. 

Chitosan salts e.g., chitosan acetate + HO CH NH3OOC-CH3 Strong antimicrobial activity, precipitate in an alkaline medium, antimicrobial activity is pH dependent 93,99 

Cotton fabric -Using BTCA or Arkofix NEC as a crosslinker 

Cotton fabric -Chitosan along with epichlorohydrin as a finishing agent 

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Commercial and Artificial Processing. Commercially, silkworm cocoons are extracted in hot soapy water to remove the sticky sericin protein. The remaining fibroin or stmctural sdk is reeled onto spools, yielding approximately 300—1200 m of usable thread per cocoon. These threads can be dyed or modified for textile appUcations. Production levels of sdk textiles in 1992 were 67,000 metric tons worldwide. The highest levels were in China, at 30,000 t, foUowed byJapan, at 17,000 t, and other Asian and Oceanian countries, at 14,000 t (24). Less than 3000 metric tons are produced annually in each of eastern Europe, western Europe, and Latin America almost no production exists in North America, the Middle East, or Africa. 1993 projections were for a continued worldwide increase in sdk textile production to 75,000 metric tons by 1997 and 90,000 metric tons by 2002 (24). 

All silks are extrusion spun into a protective cocoon before the larva undergoes metamorphosis. This cocoon consists of a continuous double strand of fibroin protein, conglutinated by the sericin protein, which acts as a binder to glue the threads into the cocoon shell. 

Functional properties of some synthetic fibres can be improved by coating with silk sericin protein. Sericin modified polyester have been reported by Yamada Matsunaga [16] and Wakabayashi and Sugioka [17]. The sericiiHnodified polyester is five times more hydroscopic than untreated polyesters. Althoi sericin tqiplication on tmctiles for antibacterial property enhancement has not been reported as yet, but it has a potential for such an application and our group is expltning the same. 

The only way to extract sericin, known so far, is recovering it from cocoon cooking water. The main methods used are membrane filtration (Fabiani et al., 1996 Capar et al., 2008 Vaithanomsat and Kitpreechavanich, 2008) and ethanol precipitation, in which ethanol is added to the waste water (Wu et al., 2007 Oh et al., 2011). Ethanol precipitation is also suitable for sericin extraction from aqueous 2 M urea solutions after boiling cocoons for 5 min (Tsubouchi et al., 2005). To obtain sericin in its native form, Teramoto et al. have used a silkworm mutant called sericin hope silkworm . Cocoons of this special silkworm strain consist almost exclusively of sericin and resemble a good model to study native sericin proteins (Teramoto et al., 2005, 2006). 

Commercial and Artificial Processing. Commercially, silkworm cocoons are extracted in hot soapy water to remove the sticky sericin protein. The remaining fibroin or structural silk is reeled onto spools, yielding approximately 300-1200 m of usable thread per cocoon. These threads can be dyed or modified... 

Silk fibers from the Bombyx mori silkworm have a 5-10 micron sized triangular cross section. The fibroin-rich chain is composed mostly of beta-sheets, due to a 59-mer amino acid repeat sequence. Silkworm fibers are extmded from two silkworm glands as a pair of primary filaments (brin) that are stuck together with sericin proteins acting like glue. Silk is one of the strongest natural fibers but loses up to 20% of its strength when wet. 

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