Oxidation Mechanism Of Low Molecular Weight Dextran And Preparation Of Iron Dextran

Dextran is a kind of biological polysaccharides which has high medical values.Dextran has abundant hydroxyl functional groups that can be chemically modified.The oxidation is one of the methods that are commonly used in chemical modification.Iron dextran is one of the important dextran derivatization.Iron dextran is also used in treating severe anemia or iron deficiency.This work studied the process of oxidation in order to improve the process of iron dextran preparation.The oxidation process used different types of reagents.A detailed study has been made on the oxidation process and products.This work laid the foundation for improving the quality of iron dextran.The complextion process was improved in order to get the iron dextran with high water solubility and high iron contents.The research results are as follows:(1)Firstly,the oxidation process of low molecular weight dextran was studied by us.The results showed that 55°C is suitable for oxidation.The content of carboxyl groups increased in the oxidation due to the increase of reaction rate as a result of the increased amount of Na Cl O and Na Br.Interestingly,both the amount of Na Cl O and Na Br can affect the contents of carboxyl groups.However,the impact of Na Cl O was more pronounced.The physical and chemical properties of oxidized dextran were significantly changed.What’s more,the size of oxidation products decreased.The introduction of carboxyl groups as hydrophilic groups and the damage of crystal structure could improve the solubility of dextran.Moreover,the research result indicates the oxidized dextran with good thermal stability.Glucose rings of oxidized dextran partly opened and contained carboxyl groups in C-OH.However,with the increases of oxidation degree,the complex mixture of products produced.(2)Secondly,the comparative study has been carried by using different types of reagents.Degradation of oxidized dextran during Na OH modification is inevitable,particularly in conditions where higher carboxyl contents were obtained;moreover,dextran can undergo different degradation reactions.The oxidation reaction is highly influenced by the p H adjustment.Less concentration of Na OH could be applied to avoid the significant degradation brought about by Na Cl O/Na Br modification.With this,carboxyl-modified dextran with specific oxidation of the aldehyde end group,moderate molecular size,and carboxyl contents can be obtained.(3)Lastly,the complextion process was improved.For low molecular weight dextran(Mw 5400 Da),the uitable reaction ratio of the mass of dextran and Ferric chloride is 1:1.8.For low molecular weight dextran(Mw 1000 Da),the suitable reaction ratio of the mass of dextran and Ferric chloride is 1:2.5.For low molecular weight dextran(Mw 3000 Da),the suitable reaction ratio of the mass of dextran and Ferric chloride is 1:2.0.For low molecular weight dextran(Mw 7000 Da),the suitable reaction ratio of the mass of dextran and Ferric chloride is 1:1.7.The iron dextran has different iron contents because of dextran has different molecular weight.The smaller the molecular weight of dextran can complexed with more iron,so the iron dextran with higher iron contents and good solubility.All in all,this study researched on the oxidation of low molecular weight dextran and the mechanism of oxidation process,provides a theoretical basis for the oxidation of dextran.It lays a foundation for the preparation and industrial application of iron dextran.