Study On The Pigment Components Of Dioscorea Cirrhosa Lour And Its Affinity Performance With Silk Fibroin

Gummed Canton silk is a kind of traditional silk fabric which is popular in Guangdongprovince, this tough fabric is well accepted by the people in hot and humid area for its uniqueproperties such as good rinsibility, quick drying, cool and pleasant, good durability andwaterproof breathable property. Gummed Canton silk is produced by using silk, pigmentextracted from Dioscorea Cirrhosa Lour roots and specific mud. The whole production process ismanual, and this cumbersome process depends much on environment which makes itsproduction efficiency low. In fact, the real reason is that its production mechanism is not yetknown. This paper studied the components of the pigment extracted from Dioscorea CirrhosaLour roots and the affinity performance between pigment and silk fibroin. Gel columnchromatography was used to separate the pigment, the main type of components were analyzedby modern detection techniques. According to the results of preliminary analysis on theingredient of the pigment, silk fibroin and the pigment were blended to prepare films, and thestructure and properties of the blend membrane were studied.Aiming at exploring the components of the pigment extracted from Dioscorea Cirrhosa Lourroots, the gel column chromatography was used to separate the pigment, and two main types ofcomponents were obtained: dark brown pigment and milky white substance. Diagnose reagentsreactions, UV-VIS spectra, infrared absorption spectra and MALDI-TOF mass spectra of theproducts were analyzed, the results showed that the dominant ingredient of the pigment wascondensed tannins, which were procyanidin polymers below tetramer; the main ingredient of themilky white substance was polysaccharide, which contained pectin and starch rather than protein.The Vanillin-hydrochloric acid method and Phenol-sulfuric acid method were used to quantifythe content of tannins and polysaccharide of pigment from Dioscorea Cirrhosa Lour roots, theaverage content of which were determinated as47.7%and10.2%. The pigment extracted fromDioscorea Cirrhosa Lour roots and the dark brown pigment showed good antibacterial propertyagainst staphylococcus aureus.Silk fibroin and pigment extracted from Dioscorea Cirrhosa Lour roots were blended in aqueous solution and prepared silk fibroin blend films, the structure of blend films were analyzedby using X-ray diffractograms, infrared absorption spectra, differential scanning calorimetryand SEM, the mechanical property, water vapour transmission and antibacterial property werealso investigated. The results showed that the main structure of the blend films was random coil,but when the amount of the pigment reached20%or30%, the structural transformation of silkfibroin protein from random coil to β-sheet occured. An optimum pigment content around20%in blend films gave the best tensile strength, but limited loss of water vapour transmission. Theblend films became more brittle because of the addition of pigment. At the same time, the blendfims showed good antibacterial property against staphylococcus aureus.In order to further study the affinity performance between silk fibroin and pigment, silk fibroinwas blended with the dark brown pigment and the silk fibroin-purified pigment films wasprepared. The interactions between silk fibroin and purified pigment molecules resulted inimmobilization of the side chains and therefore affected the arrangement of silk fibroin as anincrement in glass transition temperature observed. An optimum pigment content around10%inblend films gave the best tensile strength. The water vapour transmission changed a little but theblend films became more brittle because of the addition of pigment. At the same time, when theamount of the dark brown pigment raised to10%, the films showed a bacteriostasis rate of99.5%against staphylococcus aureus.