Department of Material Science and Engineering, Stanford University , Stanford, California 94305-2004, United States.
ACS Appl Mater Interfaces. 2014 Dec 10;6(23):21446-53. doi: 10.1021/am506443e. Epub 2014 Nov 7.
This study describes the design and synthesis of amphiphilic silica nanoparticles for the stabilization of aqueous drops in fluorinated oils for applications in droplet microfluidics. The success of droplet microfluidics has thus far relied on one type of surfactant for the stabilization of drops. However, surfactants are known to have two key limitations: (1) interdrop molecular transport leads to cross-contamination of droplet contents, and (2) the incompatibility with the growth of adherent mammalian cells as the liquid-liquid interface is too soft for cell adhesion. The use of nanoparticles as emulsifiers overcomes these two limitations. Particles are effective in mitigating undesirable interdrop molecular transport as they are irreversibly adsorbed to the liquid-liquid interface. They do not form micelles as surfactants do, and thus, a major pathway for interdrop transport is eliminated. In addition, particles at the droplet interface provide a rigid solid-like interface to which cells could adhere and spread, and are thus compatible with the proliferation of adherent mammalian cells such as fibroblasts and breast cancer cells. The particles described in this work can enable new applications for high-fidelity assays and for the culture of anchorage-dependent cells in droplet microfluidics, and they have the potential to become a competitive alternative to current surfactant systems for the stabilization of drops critical for the success of the technology.
本研究描述了两亲性硅纳米粒子的设计和合成，用于稳定氟油中的水相液滴，以应用于液滴微流控技术。液滴微流控技术的成功迄今为止依赖于一种类型的表面活性剂来稳定液滴。然而，表面活性剂有两个关键的局限性：（1）液滴间的分子迁移导致液滴内容物的交叉污染；（2）与贴壁哺乳动物细胞的生长不兼容，因为液-液界面太软，不利于细胞黏附。纳米粒子作为乳化剂可以克服这两个局限性。粒子通过不可逆地吸附到液-液界面上，有效地减轻了不希望的液滴间分子迁移。它们不像表面活性剂那样形成胶束，因此消除了液滴间迁移的主要途径。此外，粒子在液滴界面上提供了刚性的固体样界面，细胞可以黏附和扩展，因此与贴壁哺乳动物细胞（如成纤维细胞和乳腺癌细胞）的增殖兼容。本文所述的粒子可以为高保真度测定和在液滴微流控中培养锚定依赖性细胞提供新的应用，并且它们有可能成为目前用于稳定对技术成功至关重要的液滴的表面活性剂系统的一种有竞争力的替代品。
