Polymeric micelles based on poly(ethylene oxide) and α-carbon substituted poly(ε-caprolactone): An in vitro study on the effect of core forming block on polymeric micellar stability, biocompatibility, and immunogenicity

A series of block copolymers based on methoxy poly(ethylene oxide)-block-poly(epsilon-caprolactone) (PEO-b-PCL), PEO-b-PCL bearing side groups of benzyl carboxylate (PEO-b-PBCL), or free carboxyl (PEO-b-PCCL) on the PCL backbone with increasing degrees of polymerization of the PCL backbone were synthesized. Prepared block copolymers assembled to polymeric micelles by co-solvent evaporation. The physical stability of prepared micelles was assessed by measuring their tendency toward aggregation over time using dynamic light scattering (DLS). The resistance of micelles against dissociation in the presence of a micelle destabilizing agent, i.e., sodium dodecyl sulfate (SDS), was also investigated using DLS. The rate of micellar core degradation was determined using H-1 NMR for polymer molecular weight measurement upon incubation of micelles in PBS (pH = 7.4) at 37 degrees C followed by dialysis of the remaining polymer at different time intervals. The effect of pendent group chemistry in the micellar core on the adsorption of serum proteins to micellar structure was then evaluated using Bradford Protein assay kit. Finally, the effect of micellar core structure on the induction of bone marrow derived dendritic cell (BMDC) maturation and secretion of IL-12 was studied as a measure of micellar immunogenicity. The results showed micelle structures from polymers with higher degree of polymerization in the hydrophobic block and/or those with more hydrophobic substituents on the core-forming block, to be more stable. This was reflected by a decreased tendency for micellar aggregation, reduced dissociation of micelles in the presence of SDS, and diminished core degradation. All micelles were shown to have insignificant adsorption of serum protein suggesting that the hydrophilic PEO shell provided sufficient protection of the core. However, the protein adsorption increased with increase in the hydrophobicity and molecular weight of the core-forming block. Irrespective of the micellar core structure, all tested micelles were found to be non-immunogenic in BMDCs. (c) 2015 Elsevier B.V. All rights reserved.

合成了一系列基于甲氧基聚（环氧乙烷）-嵌段-聚（ε-己内酯）（PEO - b - PCL）的嵌段共聚物，即在PCL主链上带有苯甲酸苄酯侧基（PEO - b - PBCL）或游离羧基（PEO - b - PCCL）且PCL主链聚合度逐渐增加的嵌段共聚物。通过共溶剂蒸发将制备的嵌段共聚物组装成聚合物胶束。通过使用动态光散射（DLS）测量其随时间的聚集趋势来评估所制备胶束的物理稳定性。还使用DLS研究了胶束在胶束去稳定剂（即十二烷基硫酸钠（SDS））存在下的抗解离能力。通过在37℃下将胶束在PBS（pH = 7.4）中孵育，然后在不同时间间隔对剩余聚合物进行透析，使用1H - NMR测量聚合物分子量来确定胶束核的降解速率。然后使用Bradford蛋白质检测试剂盒评估胶束核中侧基化学对血清蛋白吸附到胶束结构的影响。最后，研究了胶束核结构对骨髓来源树突状细胞（BMDC）成熟和IL - 12分泌的诱导作用，以此作为胶束免疫原性的衡量指标。结果表明，由疏水嵌段中聚合度较高的聚合物和/或在成核嵌段上具有更多疏水取代基的聚合物形成的胶束结构更稳定。这体现在胶束聚集趋势降低、在SDS存在下胶束解离减少以及核降解减弱。所有胶束对血清蛋白的吸附均不显著，这表明亲水性的PEO外壳为核提供了足够的保护。然而，随着成核嵌段的疏水性和分子量增加，蛋白质吸附增加。无论胶束核结构如何，在BMDC中所有测试的胶束均无免疫原性。（c）2015 Elsevier B.V.保留所有权利。