Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Langmuir. 2010 Sep 21;26(18):14479-87. doi: 10.1021/la1023136.
Cross-flow membrane emulsification (XME) is a method for producing highly uniform droplets by forcing a fluid through a small orifice into a transverse flow of a second, immiscible fluid. We investigate the feasibility of using XME to produce monodisperse solid microspheres made of a hydrolyzable polymer and a hydrophobic drug, a model system for depot drug delivery applications. This entails the emulsification of a drug and polymer-loaded volatile solvent into water followed by evaporation of the solvent. We use a unique side-view visualization technique to observe the details of emulsion droplet production, providing direct information regarding droplet size, dripping frequency, wetting of the membrane surface by the two phases, neck thinning during droplet break off, and droplet deformation before and after break off. To probe the effects that dissolved polymers, surfactants, and dynamic interfacial tension may have on droplet production, we compare our results to a polymer and surfactant-free fluid system with closely matched physical properties. Comparing the two systems, we find little difference in the variation of particle size as a function of continuous phase flow rate. In contrast, at low dripping frequencies, dynamic interfacial tension causes the particle size to vary significantly with drip frequency, which is not seen in simple fluids. No effects due to shear thinning or fluid elasticity are detected. Overall, we find no significant impediments to the application of XME to forming highly uniform drug-loaded microspheres.
错流膜乳化（XME）是一种通过迫使流体通过小孔进入第二不相容流体的横向流动来生产高度均匀液滴的方法。我们研究了使用 XME 生产由可水解聚合物和疏水性药物组成的单分散固体微球的可行性，这是用于药物储存应用的模型系统。这需要将载药和载聚合物的挥发性溶剂乳化成水，然后蒸发溶剂。我们使用独特的侧视可视化技术来观察乳液液滴生成的细节，提供有关液滴大小、滴落频率、两相在膜表面的润湿、液滴断开时颈部变薄以及断开前后液滴变形的直接信息。为了探究溶解聚合物、表面活性剂和动态界面张力可能对液滴生成的影响，我们将我们的结果与具有相近物理性质的无聚合物和无表面活性剂的流体系统进行了比较。比较这两个系统，我们发现连续相流速作为函数的粒径变化几乎没有差异。相比之下，在低滴落频率下，动态界面张力会导致粒径随滴落频率显著变化，而在简单流体中则不会出现这种情况。未检测到由于剪切稀化或流体弹性引起的影响。总体而言，我们发现 XME 在形成高度均匀的载药微球方面没有明显的障碍。
