Study On Structure Of Dictyoploca Japonica Cocoon/Fiber And Its Regulation Performance In Biomineralization

The research and applications of Dictyoploca japonica has been widely reported in textile and clothing industry.However,there is no report on the structure of cocoon and the applications of silk protein in other fileds.In this reseach,we studied the structure of Dictyoploca japonica silkworm and evaluated the feasibility of silk fibroin in biomineralization.We conducted a preliminary study on the structure of chestnut silk by SEM,FTIR,XRD,TG.The Dictyoploca japonica cocoon was shuttle-shaped like a lantern with a color of chestnut brown or light brown.We can observe pupa directly.The diameter of pore was from 0.7 to 0.22 mm and the number of pore in the cocoon was about 300,which had a polygonal and specific shape,but the overall was regular.There were scattered Dictyoploca japonica fibers and minerals on the surface of the Dictyoploca japonica chrysalis.The diameter of Dictyoploca japonica fiber before degumming was 80 ?m.The fiber surface was covered with sericin,which was rough.The surface of the Dictyoploca japonica fiber after degumming was relatively smooth and flat that the diameter was about 140 ?m which was 4 times than before degumming.According to the results of infrared and X-ray diffraction,The ?-fold is the main structure of the Dictyoploca japonica silk.According to the EDS results,we also found that the surface of the Dictyoploca japonica fiber is not only coated with sericin,but also contains mineral elements such as Al,Si,Ca,and Zr.Subsequently,we conducted a preliminary exploration of the feasibility of the applications of Dictyoploca japonica silk fibroin in the field of biomineralization.Our studies showed that a uniform mineralized layer of calcium phosphate can be formed on the surface of Dictyoploca japonica fiber after degumming,the formation and morphology of the sheet are not only related to the concentration of calcium ions,but also related to temperature,reaction time and p H.Calcium ion concentration is the main factors of the layer morphology.When the calcium ion concentration is 100 mmol/L,a uniform continuous layer structure of calcium phosphate can be formed;when the calcium ion concentration is 1 mmol/L,a uniform calcium phosphate particle layer structure can be formed.The morphology and crystal form of calcium carbonate can be regulated by the Dictyoploca japonica silk fibroin.When the silk fibroin was 2.0 g/L and the p H was greater than 7.0,the silk fibroin gradually loses its ability to regulate morphology and crystal of calcium carbonate.When the p H was 6.8 and the reaction time was 30-40 min,spherical calcium carbonate can be obtained which was a diameter of about 4 ?m.However,the reaction time and p H had little influence on the crystal form of calcium carbonate;the temperature had the greatest effect on the crystal form and morphology of calcium carbonate.When the temperature reached 60-80°C,the proportion of formed vermiculite can reach more than 70%.At this time,calcium carbonate was a cluster of flowers.By coprecipitation method and hydrothermal method,we studied the mineralization of hydroxyapatite by using silk fibroin as a reference.The results showed that under the action of Dictyoploca japonica silk fibroin,uniform nanometer scale hydroxyapatite can be prepared by coprecipitation or hydrothermal method.Dictyoploca japonica silk fibroin has influence on the morphology and dispersion of hydroxyapatite prepared.