Department of Pharmaceutics and Analytical Chemistry, University of Copenhagen, Copenhagen Ø, Denmark.
Eur J Pharm Biopharm. 2011 Jan;77(1):26-35. doi: 10.1016/j.ejpb.2010.11.008. Epub 2010 Nov 18.
Poly(DL-lactide-co-glycolide acid) (PLGA) is an attractive polymer for delivery of biopharmaceuticals owing to its biocompatibility, biodegradability and outstanding controlled release characteristics. The purpose of this study was to understand and define optimal parameters for preparation of small interfering RNA (siRNA)-loaded PLGA nanoparticles by the double emulsion solvent evaporation method and characterize their properties. The experiments were performed according to a 2(5-1) fractional factorial design based on five independent variables: The volume ratio between the inner water phase and the oil phase, the PLGA concentration, the sonication time, the siRNA load and the amount of acetylated bovine serum albumin (Ac-BSA) in the inner water phase added to stabilize the primary emulsion. The effects on the siRNA encapsulation efficiency and the particle size were investigated. The most important factors for obtaining an encapsulation efficiency as high as 70% were the PLGA concentration and the volume ratio whereas the size was mainly affected by the PLGA concentration. The viscosity of the oil phase was increased at high PLGA concentration, which explains the improved encapsulation by stabilization of the primary emulsion and reduction of siRNA leakage to the outer water phase. Addition of Ac-BSA increased the encapsulation efficiency at low PLGA concentrations. The PLGA matrix protected siRNA against nuclease degradation, provided a burst release of surface-localized siRNA followed by a triphasic sustained release for two months. These results enable careful understanding and definition of optimal process parameters for preparation of PLGA nanoparticles encapsulating high amounts of siRNA with immediate and long-term sustained release properties.
聚（DL-丙交酯-co-乙交酯酸）（PLGA）因其生物相容性、可生物降解性和出色的控制释放特性，是一种用于生物制药递送的有吸引力的聚合物。本研究的目的是了解和定义通过双乳液溶剂蒸发法制备载有小干扰 RNA（siRNA）的 PLGA 纳米粒的最佳参数，并对其性质进行表征。实验根据基于五个独立变量的 2(5-1)分数部分设计进行：内水相与油相的体积比、PLGA 浓度、超声时间、siRNA 负载和添加到内水相中稳定初级乳液的乙酰化牛血清白蛋白（Ac-BSA）的量。考察了这些变量对 siRNA 包封效率和粒径的影响。获得高达 70%的包封效率的最重要因素是 PLGA 浓度和体积比，而粒径主要受 PLGA 浓度的影响。高 PLGA 浓度会增加油相的粘度，这解释了通过稳定初级乳液和减少 siRNA 向外部水相泄漏来提高包封效率的原因。添加 Ac-BSA 可提高低 PLGA 浓度下的包封效率。PLGA 基质可保护 siRNA 免受核酸酶降解，并提供表面定位 siRNA 的快速释放，随后持续两个月的三相缓释。这些结果使我们能够仔细了解和定义制备包封大量 siRNA 的 PLGA 纳米粒的最佳工艺参数，这些纳米粒具有即刻和长期持续释放的特性。
