Effect Of Ultrasonication And Different Source Blend On The Fibril-formation And Gel Properties Of Collagen

Collagen represents the most abundant connective tissue protein in multicellular animals including humans.Its biocompatibility and biodegradability have led to its widespread use as a biomaterial.Recently,with the demand for collagen products increased and zoonotic diseases(such as mad cow disease and foot and mouth disease)and religious beliefs astrict mammal collagen extraction,fish skin,which is one the fish processing waste,receives much concern.But compared with the mammal collagen,the collagen extracted from fish has lower denaturation temperature and promote the cell proliferation ability and so on.And the thermal stability of fish collagen is influenced by environment.In order to improve the performance of collagen from fish,this thesis studies the ultrasonic processing and heterologous collagen blend on the fibril-formation and gel properties of collagen.Controlling the fibril-formation process of collagen in vitro to fabricate novel biomaterials is a new area in the field of collagen research.This study aimed to determine the effect of ultrasonication on collagen fibril formation and the properties of the resulting collagen gels.Native collagen,extracted from the skin of grass carp,self-assembled under ultrasonic conditions(at different ultrasonic power and duration).The self-assembly kinetics,physical and cell growth-promoting properties of the collagen gels were analyzed and compared.The results showed that the self-assembly rate of collagen was increased by ultrasonication at the nucleation stage.The textural properties of collagen gels also changed after ultrasonication at the nucleation stage.Texture profile analysis and cell proliferation assays showed that ultrasonication produced softer collagen gel colloids,which were more suitable for cell proliferation than the untreated collagen gels.Heterologous collagen blend was used to study the existence of mixed collagen fibril.Native collagen,extracted from the skin of bullfrog and pig,self-assembled after different mixing ratio.The self-assembly kinetics,fibrillar morphology,and physical and cell growth-promoting properties of the collagen gels were analyzed and compared.The results indicated that novel collagen hybrid fibrils were assembled by neutralizing a mixture of type I bullfrog skin collagen solution and porcine skin collagen solution with a phosphate buffer saline at 30°C.Fibril reconstruction process(F1P1),that is the nucleation?growth and plateau of mixed type I collagen fibril of bullfrog and pig,was higher than that of the individual collagen species of bullfrog or pig.The fibrillogenic mixed collagen fibril had a greater resistance to return to the solution in comparison with the counterpart consisting solely of bullfrog collagen.On the basis of the above research,the structure and properties of mixture of bullfrog and pig collagen solution(F1P1)were discussed.Fibril morphologies showed the mean fibril diameters of the mixture collagen samples were 96±18nm,was thinner than that of the sole bullfrog and pig samples(p<0.05).The mean lengths of D-periodicity measured from TEM image were 66.2±3.5nm(bullfrog),67.8±2.8nm(pig)and 62.5±1.9nm(mixture).The denaturation temperature of the mixed collagen gel(49?)was about 5°C higher than that of bullfrog,and about 2 °C lower than that of pig.Other physicochemical properties of the mixed collagen gel were observed to be different with those of bullfrog and pig collagen gels.