Nagahama Koji, Mori Yousuke, Ohya Yuichi, Ouchi Tatsuro
Department of Applied Chemistry, Faculty of Engineering and High Technology Research Center, Kansai University, Suita, Osaka, Japan.
Biomacromolecules. 2007 Jul;8(7):2135-41. doi: 10.1021/bm070206t. Epub 2007 Jun 9.
Monodisperse stereocomplex nanogels were obtained through the self-assembly of an equimolar mixture of dextran-graft-poly(L-lactide) (Dex-g-PLLA) and dextran-graft-poly(D-lactide) (Dex-g-PDLA) amphiphilic copolymers with well-defined composition in a dilute aqueous solution. The stereocomplex nanogel possessed partially crystallized cores of hydrophobic polylactide (PLA) and the hydrophilic dextran skeleton by intra- and/or intermolecular self-assembly between PLLA and PDLA chains. The stereocomplex nanogels exhibited significantly lower critical aggregation concentration (CAC) value as well as stronger thermodynamic stability compared with those of the corresponding L- or D-isomer nanogels. The mean diameter of the stereocomplex nanogels was 70 nm with narrow size distribution, implying they were well-defined and presumably nanogels. Furthermore, stereocomplex nanogel exhibited strong kinetic stability. The tunable degradation properties of Dex-g-PLA nanogels were achieved by varying the number of grafted PLA chains as well as applying stereocomplexation. This study demonstrates the advantage of stereocomplexation in the design of biodegradable nanogels with enhanced stability.
通过在稀水溶液中使具有明确组成的葡聚糖接枝聚（L-丙交酯）（Dex-g-PLLA）和葡聚糖接枝聚（D-丙交酯）（Dex-g-PDLA）两亲共聚物的等摩尔混合物自组装，获得了单分散立体复合纳米凝胶。立体复合纳米凝胶通过PLLA和PDLA链之间的分子内和/或分子间自组装，拥有疏水性聚丙交酯（PLA）的部分结晶核和亲水性葡聚糖骨架。与相应的L-或D-异构体纳米凝胶相比，立体复合纳米凝胶表现出显著更低的临界聚集浓度（CAC）值以及更强的热力学稳定性。立体复合纳米凝胶的平均直径为70nm，尺寸分布狭窄，这意味着它们具有明确的定义，大概是纳米凝胶。此外，立体复合纳米凝胶表现出很强的动力学稳定性。通过改变接枝的PLA链的数量以及应用立体复合作用，实现了Dex-g-PLA纳米凝胶的可调节降解性能。这项研究证明了立体复合作用在设计具有增强稳定性的可生物降解纳米凝胶方面的优势。
