Study Of The Ultrastructure And Stability Of Alginate-Chitosan Polyelectrolyte Complex

The objective of this study is to investigate the ultrastructure and stability of sodium alginate-chitosan polyelectrolyte complexes.The morphological characteristics of sodium alginate-carboxymethyl polyelectrolyte complexes were initially analyzed using atomic force microscopy combined with basic thermodynamic and electrostatic mechanics principles,and then traced from the results of microscopic imaging and speculated on the more microscopic level.On the mechanism of action;through the preparation of sodium alginate-chitosan hydrogel,its water retention and ion adsorption were studied quantitatively;finally the gel beads prepared by extrusion method were used to explore the corresponding structure and mechanical properties.(1)Sodium alginate and carboxymethyl chitosan could form a stable polyelectrolyte complex.The single-component sodium alginate self-assembled form was a fiber network structure and the carboxymethyl chitosan was a lamellar structure.After the mixture,the self-assembly forms changed significantly: When the concentration and mass ratio of sodium alginate were maintained Invariable,with the increase of the carboxymethyl chitosan content,the self-assembly morphology of sodium alginate gradually transitions from a spatial network structure to a planar multi-layer aggregation structure,resulting in a large amount of granular aggregates on the surface of the sample,and the surface roughness increases significantly;(2)Sodium alginate and chitosan/carboxymethyl chitosan could form a gel under hydration conditions.After cross-linked drying,their water absorption properties were related to the shape,quality and degree of internal coagulation of the selected gel: The higher the content of chitosan /carboxymethyl chitosan,the water absorption,water holding capacity and ion adsorption of the gel were better,and the effect of carboxymethyl chitosan on the system was more significant than chitosan.;(3)Ca,Mg,Fe,Zn,Cu and other divalent ions had an effect on the stability of sodium alginate-chitosan microcapsules: The gel microcapsules formed under the influence of Ca and Mg were the most stable and had the longest storage time;Fe,Zn and Cu three groups of gel microcapsules exhibited varying degrees of instability.The comparison showed that the interaction between the divalent metal cation and the sodium alginate-chitosan system is related to the ionic radius of the metal cation: the larger the ionic radius,the larger gap between the sodium alginate molecular chains and the larger of the sodium alginate gel.The lower the degree of spatial compaction of the capsule,the easier the ion exchanged between inside and outside the gel microcapsules,and the more unstable the gel microcapsules produced.In this paper,the relationship between the ultrastructure and stability of sodium alginate-chitosan polyelectrolyte complexes was thoroughly investigated,and the microscopic morphology observation of polyelectrolyte complexes was unified with the research on macroscopical properties.It provides corresponding theoretical basis for its practical application,especially in biology.