The Studies Of Preparation And Drug Adsorbing Properties Of Cross-linked Starch Made With Maize Starch Physically Modified With Ball-mill

This study compared two kinds of ball-mill, namely milling with ethanol and water as mediums, and prepared cross-linked starch with maize starch physically modified with ball-mill as loading material of cationic drug. The results concluded from experiments were as follows.1. When subjected to ball-mill treatment, pasting temperature (PT), peak viscosity (PV), morphology, granule size distribution and crystalline property of starch were changed to some degree, whether the medium be ethanol or water. The starch was apt to gelatinize during milling when the medium was water. When the medium was water, the effect of short time ball-mill on starch property was not as great as that of long time ball-mill with ethanol as medium.2. In Na₂CO₃ solution adding NaCl, the cross-linking efficiency was good, and the phosphorus contents of cross-linked starch with starches physically modified with ball-mill were higher than that with native starch. And in Na₂CO₃ solution adding NaCl, the phosphorus content and adsorbing content of model cationic drug Methylene Blue (MB) of cross-linked starch made with starch modified by ball-mill with the speed of 450r/min was higher than the ones with other speeds and the native one. Through single factor and Response Surface Design (RSD) experiments, the optimum technology from RSD was pH 10.25, temperature 60℃, and reaction time 5h, with which the adsorbing content of the product was 27.30mg/g, and the phosphorus content was 0.2002%.3. Cross-linking reaction increased the diameters of starch modified with ball-mill, and the average diameter of the product was 18.64μm. The MB adsorbing efficiency of the product was high. With the increase of MB concentration, the adsorbing content increased at first, and kept unchanged then. The adsorbing content decreased as the temperature increased. The MB adsorption of the product fitted well with pseudo-second-order model, and the isothermal model was fitted well with Langmuir model. The adsorption process was an exothermic process, and a spontaneous one when the temperature was 25℃. In PBS buffer, the releasing property of the product was great and approximately 36% of the drug could not release to the solution. Besides, the degredation property was good, for the degredation rate was 17.38% when hydrolyzed withα-1,4-Glucan glucohydrolace for 8h. From the data of adsorption, granule size distribution, release rate and degradation rate, the product could replease starch microsphere to some extent.