Department of Physics, National University of Singapore, 117551, Singapore.
Nanoscale. 2019 Jan 31;11(5):2299-2305. doi: 10.1039/c8nr08922a.
Micelles formed through the aggregation of amphiphilic block copolymers are ideal drug nanocarriers. Despite their importance in nanomedicine, the detailed mechanisms through which micelles form and copolymers encapsulate the target nanomaterials are unclear. Here, using in situ liquid cell transmission electron microscopy imaging, we capture both the dynamics of micelle formation and their encapsulation of gold nanoparticles (NPs) in an aqueous solution. Our observations reveal that the amphiphilic block copolymers aggregate and rearrange to form a micelle with a hydrophobic and rigid core, surrounded by a corona of hydrophilic blocks that extend into the solution. These micelles are stable against coalescence, and once mature, they do not merge. We also show that the encapsulation of hydrophobic NPs is a self-limiting process, which occurs through gradual adsorption of block copolymers; the growth of a polymeric shell around the NPs, shielding them from water, ceases when the NPs are fully covered by the adsorbed copolymers. The insights from these observations are of fundamental importance for the design of biocompatible soft materials.
胶束是通过两亲性嵌段共聚物的聚集形成的，是理想的药物纳米载体。尽管它们在纳米医学中很重要，但胶束形成和共聚物包封靶标纳米材料的详细机制尚不清楚。在这里，我们使用原位液体细胞透射电子显微镜成像，在水溶液中同时捕获胶束形成的动力学及其对金纳米粒子（NPs）的包封。我们的观察结果表明，两亲性嵌段共聚物聚集并重新排列，形成具有疏水和刚性核心的胶束，亲水嵌段的冠层延伸到溶液中。这些胶束不易聚结，一旦成熟，它们就不会融合。我们还表明，疏水性 NPs 的包封是一个自限制的过程，它通过嵌段共聚物的逐渐吸附来实现；当 NPs 被吸附的共聚物完全覆盖时，NP 周围的聚合物壳的生长会停止，从而将其屏蔽在水中。这些观察结果的见解对于设计生物相容性软材料具有重要的基础意义。
