Dissolution Mechanism And Properties Of Collagen In Nitrogenous-Containing Solvents

Collagen is an important protein,which is widely distributed in various tissues of animals for maintaining the functions of living organisms.Because of good biocompatibility and degradability,collagen is widely used in food,medical and other fields.Collagen with a quaternary structure stabilized by hydrogen bonds which result in collagen is insoluble in many solvents.At present,the solvents for solubilizing collagen are strong polar substances such as strong acids and alkalis.These solvents-are not conducive to human health and environment.Therefore,an economical and environment-friendly solvent for dissolving collagen is a research focus.The acids,alkalis and salts dissolve collagen by destroying the internal hydrogen bonds of collagen.As we all know,urea is a cost-effective hydrogen bond breaker.The reaserch of dissolvign collagen with urea have been studied.Some people think that there is a strong hydrogen bond between the carbonyl group in the urea and the amino group in the collagen.N-methylmorpholine-N-oxide(NMMO)is an environment-friendly solvent.It has been used for dissolving polymers such as cellulose in recent years.The dissolution process of cellulose is a physical change by destroying hydrogen bonds between cellulose molecules.The NMMO can also be applied to the dissolution of high molecular substances such as chitosan and silk fibroin.Therefore,we applied NMMO to dissolving collagen..This thesis includes the following three aspects:First,we extracted collagen from porcine skin with acetic acid and pepsin of which the structure is type I collagen analysing by circular dichroism and SDS-PAGE gel electrophoresis.Subsequently,we studied the solubility of type I collagen in different concentrations of urea solution.The results demonstrate urea can destroyed the triple helix structure of collagen.Type I collagen can form gel in a specific concentration(10 wt%)of urea solution.Second,the N-O bond in the NMMO molecule is strongly polar,so it easily forms hydrogen bonds with the cellulose molecules.In addition,the NMMO is recyclable environmentally friendly.Therefore,we studied the solubility of collagen in NMMO.The results showed that the solubility of collagen in NMMO is much better than that in water.Thirdly,The interaction between NMMO and type I collagen was studied by circular dichroism,SDS-PAGE gel electrophoresis and visible spectrum.The results show that NMMO can destroy the triple helix structure of type I collagen.