Study On The Properties Of Self-assembly Film System Of Sodium Alginate By AFM

The properties of self-assembly films of sodium alginate(SA) were researched by atomic force microscope(AFM) in this paper.when the concentration of SA was 0.00lmg/ml, the structure of monomolecular, which was single chain and small congeries, could be observed on the mica surface by AFM. At a concentration of 0.0lmg/ml, SA aggregated wind and linear chains. And the network, which was homogeneous and tight, was presented under the condition of 0.lmg/ml. But the concentration of 0.5mg/ml was increased, the network was unhomogeneous and it's apertures were increased. Then at a concentration of l.5mg/ml, the linear chains were broken and aggregated small conglomeration, which was column and ellipse. It was found to present a branch-like fractal structure at the concentrations of 12mg/ml and 25mg/ml,while the fractal of a single twig was formed by compact stock of nanometer particles. The mechanism, which was discussed by the fractal theory, was well accordant with the diffusion-limited aggregation(DLA) mode simulated by computer. At the same time, the refined structure of lyotropic liquid crystal of SA was studied. The typical polygon showed up at the critical concentration(5% by wt.). It was the result of self-assembly of molecules and embodiment of dissipative structure under the imbalance state. Self-assembly characteristic of SA on mica surface was investigated in the paper. It was demonstrated that the structure formed was relative to the concentration.The relation between macroscopical structure and physical capability was revealed, then experiment data and theory were provided.In order to research the effect of Ca2+ on self-assembly films of SA, the self-assembly behavior of SA in the presence of calcium chloride was studied. The result showed that the self-assembly films of SA could be induced by Ca2+(5mg/ml), when its concentration arrived at 0.0lmg/ml and 0.lmg/ml.Then the typical "egg boxstructure" appeared. The result revealed that self-assembly could be induced by the interaction between micromolecule and surface active group of macromolecule.With making use of ion gelation, SA/chitosan nanomicrospheres were prepared by one step method. Topography of the microspheres were observed by AFM. The bulk of microspheres size were accordant and their surfaces were smooth. The change of encapsulation efficiency and drug loading, and in vitro release of microspheres were investigated using bovine serum albumin(BSA) as a model drug. Experimental results showed that the microspheres could be used as carrier for slow delivery of drugs.