Rübe Andrea, Hause Gerd, Mäder Karsten, Kohlbrecher Joachim
Institute of Pharmaceutical Technology and Biopharmacy, Martin-Luther-University, Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle/Saale, Germany.
J Control Release. 2005 Oct 3;107(2):244-52. doi: 10.1016/j.jconrel.2005.06.005.
The contrast variation technique in small angle neutron scattering (SANS) was used to investigate the inner structure of nanocapsules on the example of poly(D,L-lactide) (PLA) nanocapsules. The determination of the PLA and Poloxamer shell thickness was the focus of this study. Highest sensitivity on the inner structure of the nanocapsules was obtained when the scattering length density of the solvent was varied between the one of the Miglyol core and the PLA shell. According to the fit data the PLA shell thickness was 9.8 nm. The z-averaged radius determined by SANS experiments correlated well with dynamic light scattering (DLS) results, although DLS values were systematically slightly higher than the ones measured by SANS. This could be explained by taking into account the influence of Poloxamer attached to the nanocapsules surface. For a refined fit model with a second shell consisting of Poloxamer, SANS values and DLS values fitted well with each other. The characterization method presented here is significant because detailed insights into the nanocapsule and the Poloxamer shell were gained for the first time. This method could be used to develop strategies for the optimization of the shell properties concerning controlled release and to study changes in the shell structure during degradation processes.
以聚（D，L-丙交酯）（PLA）纳米胶囊为例，采用小角中子散射（SANS）中的对比变化技术研究了纳米胶囊的内部结构。本研究的重点是测定PLA和泊洛沙姆壳层的厚度。当溶剂的散射长度密度在Miglyol核和PLA壳层之一之间变化时，对纳米胶囊的内部结构具有最高的灵敏度。根据拟合数据，PLA壳层厚度为9.8nm。SANS实验测定的z平均半径与动态光散射（DLS）结果相关性良好，尽管DLS值系统性地略高于SANS测量值。考虑到附着在纳米胶囊表面的泊洛沙姆的影响，可以对此进行解释。对于具有由泊洛沙姆组成的第二壳层的精细拟合模型，SANS值和DLS值相互拟合良好。这里提出的表征方法具有重要意义，因为首次获得了对纳米胶囊和泊洛沙姆壳层的详细见解。该方法可用于制定优化壳层性能以实现控释的策略，并研究降解过程中壳层结构的变化。
