Department of Chemistry and Biochemistry, The University of Kitakyushu, 1-1 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka 808-0135, Japan.
J Phys Chem B. 2012 Jul 19;116(28):8241-50. doi: 10.1021/jp300936d. Epub 2012 Jul 6.
Poly(ethylene glycol)-block-poly(partially benzyl-esterified aspartic acid), denoted by PEG-P(Asp(Bzl)), is one of the most examined blockcopolymers for drug carriers. However, little is known about fundamental physical properties. Nine samples of PEG-P(Asp(Bzl)) with different benzylation fractions (F(Bzl)) and aspartic chain lengths (DP(Asp)) were synthesized, and the aggregation number (N(agg)), core radius (R(C)), and other structural parameters were determined with combination of light scattering and synchrotron X-ray small-angle scattering. The major factor to determine N(agg) and R(C) was found to be F(Bzl), i.e., the hydrophobic nature of the core, even though F(Bzl) was changed in the relatively small composition range from 66 to 89 mol %. When we compared the data for the same F(Bzl), the scaling theory was consistent with the core chain length dependence of both core and micelle sizes. The overcrowding nature of the tethered PEG chains on the micelles was increased about 1.3-2.9 times with increasing N(agg) compared with the unperturbed state in solutions.
聚（乙二醇）-嵌段-聚（部分苄酯化天冬氨酸），表示为 PEG-P（Asp（Bzl）），是研究最多的用于药物载体的嵌段共聚物之一。然而，对于其基本物理性质知之甚少。合成了具有不同苄基化分数（F（Bzl））和天冬氨酸链长（DP（Asp））的 9 种 PEG-P（Asp（Bzl））样品，并结合光散射和同步加速器小角 X 射线散射确定了聚集数（N（agg））、核半径（R（C））和其他结构参数。发现决定 N（agg）和 R（C）的主要因素是 F（Bzl），即核的疏水性，尽管 F（Bzl）在相对较小的组成范围内从 66 到 89mol%发生了变化。当我们比较相同 F（Bzl）的数据时，标度理论与核心和胶束尺寸的核心链长依赖性一致。与溶液中的未扰状态相比，由于在胶束上的束缚 PEG 链的拥挤性质，聚集数（N（agg））增加了约 1.3-2.9 倍。
