The microsphere formulations of Chit/TPP/Sm/Fe_3O_4/Rn were prepared by an ionic gelation technique, where Chit = chitosan, TPP = tripolyphosphate, Sm = samarium and Rn = ranitidine. Optimum of microsphere formulation exhibit magnetic and fluorescent properties with adsorption efficiency of ～92% was obtained for Chit/TPP/Sm/Fe_3O_4/Rn with ratio 400:500:50:1:20. Fluorescence intensity of microsphere formulations increased with the cumulative amount release of ranitidine, so that the changing of fluorescence intensity at wavelength of 590 nm referring to the Sm~(3+) ion could be used as indicator in DDS. With the demonstration of sustained release from microsphere formulation, it allows to investigate the applications to other drugs.
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