淀粉基微球的滴入法制备及性能

Preparation and properties of starch-based microspheres by dropping method

以玉米淀粉、木薯淀粉、糯玉米淀粉3种天然淀粉为原料,在高温糊化后以滴入法制备了淀粉基微球。采用SEM、DSC和XRD对淀粉基微球进行了表征。考察了淀粉种类、淀粉质量分数、针头孔径对淀粉基微球平均粒径的影响,探究了玉米淀粉基微球的α-淀粉酶酶解性能和在高温水溶液中的释放行为,并评价了玉米淀粉基微球负载亚甲基蓝(MB)的性能。结果表明,在糊化温度80℃、淀粉质量分数10.0%,采用内径0.21 mm的27 G型针头制备的3种淀粉基微球形貌均一,粒径介于1.0~1.5 mm之间,收率均>90%,微球内部存在不同程度的中空结构;淀粉基微球糊化放热峰基本消失、晶型改变(由典型的A型晶体结构转变为较弱的V型结晶结构)且结晶度显著降低;3种淀粉基微球平均粒径均随着淀粉质量分数和针头孔径的增大而增大,相同制备条件下,玉米淀粉基微球的平均粒径最大;玉米淀粉基微球经α-淀粉酶24 h酶解后(酶解率42.78%)基本转变为水溶物,比玉米淀粉(酶解率41.91%)有更高的酶解率;玉米淀粉基微球负载MB时,MB添加量过大会导致包封率下降、释放率增大,不利于负载。与其他玉米淀粉基载体(玉米淀粉、多孔玉米淀粉)相比,玉米淀粉基微球负载MB的载药量(2.01%±0.03%)和包封率(60.33%±0.90%)最大,在温度>70℃的水溶液中MB释放率最低,90℃水溶液中MB的释放率为73.17%±0.61%。

Starch-based microspheres were prepared via dropping method after high temperature gelatinization of three kinds of natural starch,corn starch,cassava starch and waxy corn starch,respectively,and characterized by SEM,DSC and XRD.The effects of starch type,starch mass fraction and needle aperture on the average particle size of starch-based microspheres were analyzed.The enzymolysis performance and release behavior ofα-amylase in high temperature aqueous solution of corn starch-based microspheres were studied,while the performance of methylene blue(MB)loaded onto corn starch-based microspheres was evaluated.The results showed that the three kinds of starch-based microspheres,prepared at gelatinization temperature 80℃,starch mass fraction 10.0%and with a 27 G needle of inner diameter 0.21 mm,exhibited homogeneous and different degrees of inside hollow structure,with particle size between 1.0 and 1.5 mm and yield was>90%.Meanwhile,the gelatinization heat release peak of starch-based microspheres basically disappeared,the crystal shape changed(from the typical A-type crystal structure to the weak V-type crystal structure)and the crystallinity decreased significantly.The average particle size of all three kinds of starch-based microspheres increased with the increase of starch mass fraction and needle aperture,with the average particle size of corn starch-based microspheres the largest under the same preparation conditions.After 24 h enzymatic hydrolysis byα-amylase(enzymatic hydrolysis rate 42.78%),the corn starch-based microspheres were basically transformed into water soluble matter,which had a higher enzymatic hydrolysis rate than corn starch(enzymatic hydrolysis rate 41.91%).When corn starch-based microspheres were loaded with MB,excessive MB addition caused the encapsulation rate to decrease and the release rate to increase,which was not conducive to the loading.Compared with other corn starch-based carriers(corn starch and porous corn starch),the drug loading capacity(2.01%±0.03%)and encapsulation rate(60.33%±0.90%)of MB loaded on corn starch-based microspheres were the largest.The release rate of MB was the lowest in aqueous solution with temperature>70℃,and the release rate of MB was 73.17%±0.61%in aqueous solution with 90℃.