Institute of Pharmacy, Martin-Luther-University of Halle, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany.
Eur J Pharm Sci. 2010 Jan 31;39(1-3):141-51. doi: 10.1016/j.ejps.2009.11.009. Epub 2009 Dec 1.
Oily core nanocapsules were prepared by sequential addition of positively and negatively charged polyelectrolytes based on a nanoemulsion and transformation thereof into a core-shell structure. The capsules were well characterized by photon correlation spectroscopy, laser diffraction, zeta-potential and transmission electron microscopy and feature an average size of 150nm and a negative surface charge. The aim of the current study was to improve the dispersion stability and mechanic rigidity of the capsule wall by depositing an increasing number of up to five layers. Therefore, atomic force microscopy (AFM) and ultrasonic resonator technology (URT) were applied to investigate the shell of the nanoemulsion, the intermediate and final nanocapsules in more detail. AFM was performed to investigate the shape, morphology and mechanic properties of the emulsion and capsule shell. It proved to be a feasible technique to distinguish nanoemulsions from nanocapsules by stiffness analysis. URT was utilized in order to observe the ultrasound velocity and could confirm the AFM results. Both techniques demonstrated that the shell around an oil droplet solidified with increasing number of polyelectrolyte layers. Since a solid wall might have the potential of a strong diffusion barrier, nanocapsules might present a feasible prolonged release drug delivery system in contrast to nanoemulsions.
油核纳米胶囊是通过基于纳米乳液的正、负电荷的聚电解质的顺序添加，并将其转化为核壳结构来制备的。通过光相关光谱法、激光衍射法、Zeta 电位和透射电子显微镜对胶囊进行了很好的表征，其平均粒径为 150nm，表面带负电荷。本研究的目的是通过沉积多达五层的聚电解质来提高胶囊壁的分散稳定性和力学刚性。因此，原子力显微镜（AFM）和超声谐振器技术（URT）被应用于更详细地研究纳米乳液、中间和最终纳米胶囊的壳层。AFM 用于研究乳液和胶囊壳的形状、形态和力学性能。它通过对刚度分析证明了一种能够区分纳米乳液和纳米胶囊的可行技术。URT 用于观察超声速度，并能证实 AFM 的结果。这两种技术都表明，随着聚电解质层数的增加，油滴周围的壳层固化。由于固体壁可能具有较强的扩散势垒，纳米胶囊可能与纳米乳液相比，呈现出一种可行的长效药物释放给药系统。
