Lavasanifar A, Samuel J, Kwon G S.
Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, T6G 2N8, Alberta, Canada
Colloids Surf B Biointerfaces. 2001 Oct;22(2):115-126. doi: 10.1016/s0927-7765(01)00147-3.
Block copolymers based on fatty acid esters of poly(ethylene oxide)-block-poly(hydroxy alkyl L-aspartamide) were prepared and characterized by 1H-NMR. The structure of the core-forming block was changed through application of different lengths of the poly(L-aspartamide) (PLAA) block, spacer group or fatty acid and varying the substitution level of the side chain on the polymeric backbone. Transmission electron microscopy and fluorescent probe studies provided evidence for the formation of supramolecular core/shell architectures with nanoscopic dimensions. The same techniques were used to study the effect of hydrophobic block structure on micellar size, critical micelle concentration (CMC), core polarity and viscosity of the polymeric micelles. Among the structural factors studied, it was revealed that the length of the PLAA block and the level of fatty acid attached to the polymeric backbone are the major factors affecting micellar properties. An increase in micellar size and reduction in CMC were observed when the level of fatty acid attachment to the polymeric backbone was raised. The elongation of the PLAA block, on the other hand, resulted in an increase in micellar size and core viscosity. Micellar size was the only characteristic being affected by the length of the attached fatty acid. However, a decrease in microviscosity was revealed when behenic acid (22 carbons) was attached to the core-forming block in a high level of substitution. The length of spacer group was also found to be a useful means by which the level of side chain attachment could be controlled. Chemical tailoring of the core structure in polymeric micelles may be used as an efficient means to change micellar properties. As a result, nanoscopic, spherical and stable micelles with improved core properties may be achieved to insure efficient loading and controlled release of an individual drug from the delivery system.
制备了基于聚环氧乙烷-嵌段-聚（羟烷基L-天冬酰胺）脂肪酸酯的嵌段共聚物，并通过1H-NMR对其进行了表征。通过应用不同长度的聚（L-天冬酰胺）（PLAA）嵌段、间隔基团或脂肪酸，并改变聚合物主链上侧链的取代水平，改变了形成核的嵌段的结构。透射电子显微镜和荧光探针研究为纳米尺寸超分子核/壳结构的形成提供了证据。采用相同的技术研究了疏水嵌段结构对聚合物胶束的胶束尺寸、临界胶束浓度（CMC）、核极性和粘度的影响。在所研究的结构因素中，结果表明，PLAA嵌段的长度和连接到聚合物主链上的脂肪酸水平是影响胶束性质的主要因素。当连接到聚合物主链上的脂肪酸水平提高时，观察到胶束尺寸增加，CMC降低。另一方面，PLAA嵌段的延长导致胶束尺寸和核粘度增加。胶束尺寸是唯一受连接脂肪酸长度影响的特征。然而，当山嵛酸（22个碳）以高取代水平连接到形成核的嵌段上时，微粘度降低。还发现间隔基团的长度是控制侧链连接水平的有用手段。聚合物胶束中核结构的化学剪裁可作为改变胶束性质的有效手段。因此，可以获得具有改善核性质的纳米级、球形和稳定胶束，以确保从给药系统中有效负载和控制单个药物的释放。
