Quintanar-Guerrero D, Allémann E, Doelker E, Fessi H
Pharmapeptides, Interuniversity Centre Geneva-Lyon, Archamps, France.
Pharm Res. 1998 Jul;15(7):1056-62. doi: 10.1023/a:1011934328471.
The aim of this study was to investigate whether biodegradable nanocapsules could be obtained by the emulsification-diffusion technique.
This technique consists of emulsifying an organic solution containing an oil, a polymer, and a drug in an aqueous solution of a stabilizing agent. The subsequent addition of water to the system induces solvent diffusion into the external phase, resulting in the formation of colloidal particles. Nanoparticles obtained in this way were characterized by their particle size, zeta potential, isopycnic density and drug entrapment. The shape, surface and structure of the nanocapsules were evaluated by freeze fracture scanning electron microscopy (SEM) and by atomic force microscopy (AFM).
Density gradient centrifugation confirmed the formation of nanocapsules. The density was found to be intermediate between those of nanoemulsions and nanospheres. The existence of a unique density band indicated high yields. Nanocapsule density was a function of the original oil/polymer ratio, revealing that the polymer content and, consequently, the wall thickness, can be controlled by this method. SEM and AFM showed the presence of capsular structures with smooth homogeneous walls. The versatility and effectiveness of the method were demonstrated using different lipophilic drug/oil core/wall polymer/partially water-miscible solvent systems. The mechanism of nanocapsule formation was explained as a chemical instability (diffusion stranding) generated during diffusion.
This study demonstrated that the emulsification-diffusion technique enables the preparation of nanocapsules in a simple, efficient, reproducible and versatile manner.
本研究旨在探究能否通过乳化-扩散技术制备可生物降解的纳米胶囊。
该技术包括将含有油、聚合物和药物的有机溶液在稳定剂的水溶液中乳化。随后向体系中加水，促使溶剂扩散到外相，从而形成胶体颗粒。通过粒度、zeta电位、等密度密度和药物包封率对以此方式获得的纳米颗粒进行表征。通过冷冻断裂扫描电子显微镜（SEM）和原子力显微镜（AFM）评估纳米胶囊的形状、表面和结构。
密度梯度离心法证实了纳米胶囊的形成。发现其密度介于纳米乳液和纳米球的密度之间。存在独特的密度带表明产率高。纳米胶囊密度是原始油/聚合物比例的函数，表明通过该方法可以控制聚合物含量，进而控制壁厚。SEM和AFM显示存在具有光滑均匀壁的囊状结构。使用不同的亲脂性药物/油核/壁聚合物/部分与水混溶的溶剂体系证明了该方法的通用性和有效性。纳米胶囊形成的机制被解释为扩散过程中产生的化学不稳定性（扩散滞留）。
本研究表明，乳化-扩散技术能够以简单、高效、可重复且通用的方式制备纳米胶囊。
