膜材与制备过程对血红蛋白微胶囊粒径和包埋率的影响

以单甲氧基聚乙二醇聚乳酸共聚物（PELA）为膜材用复乳溶剂扩散法制备了包含牛血红蛋白（BHb）的微胶囊，微胶囊中BHb的P₅₀和Hill系数分别为3 466 Pa和2.4左右，接近于天然BHb的生物活性。研究发现膜材种类对BHb微胶囊包埋率和粒径的影响最大，使用MPEG2000为亲水性嵌段的PELA共聚物时，包埋率最高，达到90％以上,粒径为3～5 μm左右；随着膜材浓度的增大，微胶囊包埋率和粒径均增加；随着外水相NaCl浓度的增大，微胶囊包埋率升高、粒径减小；随着外水相稳定剂PVA浓度的增大，微胶囊粒径减小，包埋率先升高后降低，在较低浓度下（10 g/L、20 g/L）包埋率较高；初乳化搅拌速率的增大，有利于包埋率的提高，但对粒径影响不大；复乳化搅拌速率的影响较复杂，当复乳液体积较大时，复乳化搅拌速率对微胶囊制备的影响规律性不明显。当固定膜材和初乳化搅拌速率时，包埋率和粒径之间存在着类似抛物线的关系，包埋率随着粒径的减小而降低。

Influence of Wall Polymer and Preparation Process on the Particle Size and Encapsulation of Hemoglobin Microcapsules

Methoxypoly (ethylene glycol)- block-poly (DL-lactide) (PELA) microcapsules containing bovine hemoglobin (BHb) were prepared by a W/O/W double emulsion-solvent diffusion process. The P50 and Hill coeffcient were 3466 Pa and 2.4 respectively, which were near to the natural bioactivity of bovine hemoglobin. The results suggested that polymer composition had significant influence on encapsulation efficiency and particle size of microcapsules. The encapsulation efficiency could reach 90% and the particle size 3 - 5 microm when the PELA copolymer containing MPEG 2000 block was used. The encapsulation efficiency and particle size increased with the concentration of PELA. Increasing the concentrations of NaCl in outer aqueous solution resulted in the increase of encapsulation efficiency and the decrease of particle size. As the concentration of stabilizer in outer aqueous solution increased in the range of 10 g/L to 20 g/L, the particle size reduced while encapsulation efficiency was increased, further increase of the stabilizer concentration would decrease encapsulation efficiency. Increasing of primary emulsion stirring rate was advantageous to the improvement of encapsulation efficiency though it had little influence on the particle size. The influence of re-emulsion stirring rate was complicated, which was not apparent in the case of large volume of re-emulsion solution. When the wall polymer and primary emulsion stirring rate were fixed, the encapsulation efficiency decreased as the particle size reduced.