Preparation And Characterization Of Drug-loaded Microspheres Based On Oxidized Alginate

With the advancement of science and technology and the improvement of people’s quality life, it spurs people to have higher requirements on every aspect, especially the aspect of the medical field about people’s health. The research scientists have always been to develop the kind of drug-loaded carrier with a long effect, long cycle and the low administration frequency. In this article, we explored three different drug-loaded carrier OSA/CS, OSA/N3 CS, OSA/NH2 CS and they were characterized by IR, TGA, SEM and other testing methods, furthermore, we compared their release properties in vitro.(1) The intermediate PHCS was synthesized by a novel method using water as solvent, and then CS derivatives N3 CS and NH2 CS were compounded. The characterization of IR and NMR indicated CS derivatives were prepared successfully. Elemental analysis results showed the degree of substitution about each reaction, due to the presence of some defects in the product, some of the product had low degree of substitution. X-ray diffraction showed that the diffraction peak of CS derivatives became weak and wider due to the destruction of the crystalline structure. TGA results showed the products’ thermal stability CS>NH2CS>N3CS.(2) Partially oxidized alginate was prepared using conventional methods in a mixed solution of ethyl alcohol/water, and the degree of oxidation of SA increases with the increasing amount of NaIO4, degree of oxidation—the molar ratio between NaIO4 and SA curve was approached to be linear. TGA indicated the order of thermal stability was SA>OSA, and the higher degree of oxidation of SA, the worse thermal stability it is.(3) Using the concentration of CS, the amount of span, different degrees of oxidation and the amount of OSA(oxidizability-55.8%)as variable, we used the method of single factor control to determine the scope of the variable applied to CCD, namely c(CS): 20-30mg/ml, v(span): 1-2ml,v(OSA): 1.5-4.5ml; using the LE, EE and grain size as index, the experiments were designed using CCD, then we analyzed them using the method of RSM based on the binomial model fitting, the results were very consistent with the analysis of the single factor; finally the method of overlapping contour was used to determine the optimum range of the experiment, namely span:1.57-1.68 ml,OSA:2.7-2.9ml,CS:25mg/ml.(4) In the range of optimum condition, we chose the condition the concentration of CS, the amount of span and OSA were respectively 25mg/ml,1.6ml,2.8ml. Under these conditions, drug-loaded carrier OSA/CS, OSA/N3 CS, OSA/NH2 CS were prepared. TGA showed that the order of thermal stability was CS/OSA>NH2CS/OSA>N3CS/OSA, but in theory NH2CS/OSA>CS/OSA, this may due to the CS/OSA containing much greater moisture. In vitro release studies, with regard to the same carrier CS/OSA containing different amount of BSA, with the increasing of BSA, the cumulative release rate was greater, the instant release condition became more obvious. Within an hour the release rate was about 25-30%, it had a certain sudden release, the cumulative rate of them could reach 70-87% within 7 days; with regard to different carrier containing the same amount of BSA, the order of the release rate was N3CS/OSA>CS/OSA>NH2CS/OSA, within an hour the release rate of N3CS/OSA and CS/OSA was about 32%, while NH2CS/OSA was 19%, the phenomenon of sudden release was suppressed, meanwhile the cumulative rate of them can reach 70-90%, the releasing period could continue more than 10 days.