Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
Institute of Pharmacy (Pharmaceutical Chemistry), Freie Universität Berlin, Königin-Luise Straße 2-4, 14195 Berlin, Germany.
Langmuir. 2020 Sep 22;36(37):10979-10988. doi: 10.1021/acs.langmuir.0c01812. Epub 2020 Sep 8.
Amphiphilic polymer nanogels (NGs) are promising drug delivery vehicles that extend the application of conventional hydrophilic NGs to hydrophobic cargoes. By randomly introducing hydrophobic groups into a hydrophilic polymer network, loading and release profiles as well as surface characteristics of these colloids can be tuned. However, very little is known about the underlying internal structure of such complex colloidal architectures. Of special interest is the question how the amphiphilic network composition influences the internal morphology and the "fuzzy" surface structure. To shine light into the influence of varying network amphiphilicity on these structural features, we investigated a small library of water-swollen amphiphilic NGs using small-angle X-ray scattering (SAXS). It was found that overall hydrophilic NGs, consisting of pure poly(-(2-hydroxypropyl)methacrylamide) (PHPMA), display a disordered internal structure as indicated by the absence of a SAXS peak. In contrast, a SAXS peak is present for amphiphilic NGs with various amounts of incorporated hydrophobic groups such as cholesteryl (CHOLA) or dodecyl (DODA). The internal composition of the NGs is considered structurally homologous to microgels. Application of the Teubner-Strey model reveals that hydrophilic PHPMA NGs have a disordered internal structure (positive amphiphilicity factor) while CHOLA and DODA samples have an ordered internal structure (negative amphiphilicity factor). From the SAXS data it can be derived that the internal structure of the amphiphilic NGs consists of regularly alternating hydrophilic and hydrophobic domains with repeat distances of 3.45-5.83 nm.
两亲性聚合物纳米凝胶 (NGs) 是很有前途的药物传递载体，可将传统的亲水性 NGs 的应用扩展到疏水性载物。通过随机将疏水性基团引入亲水性聚合物网络中，可以调整这些胶体的载药和释放曲线以及表面特性。然而，对于这种复杂胶体结构的内部结构，人们知之甚少。特别感兴趣的是，两亲性网络组成如何影响内部形态和“模糊”表面结构。为了深入了解不断变化的网络两亲性对这些结构特征的影响，我们使用小角 X 射线散射 (SAXS) 研究了一小批水膨胀的两亲性 NGs。结果发现，由纯聚（-（2-羟丙基）甲基丙烯酰胺）（PHPMA）组成的整体亲水性 NGs 显示出无序的内部结构，这表明不存在 SAXS 峰。相比之下，具有各种疏水性基团（如胆固醇（CHOLA）或十二烷基（DODA））的两亲性 NG 存在 SAXS 峰。NG 的内部组成被认为在结构上与微凝胶同源。Teubner-Strey 模型的应用表明，亲水性 PHPMA NGs 具有无序的内部结构（正两亲性因子），而 CHOLA 和 DODA 样品具有有序的内部结构（负两亲性因子）。从 SAXS 数据可以推断出，两亲性 NGs 的内部结构由规则交替的亲水性和疏水性域组成，重复距离为 3.45-5.83nm。
