Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
Soft Matter. 2020 Mar 28;16(12):3082-3087. doi: 10.1039/c9sm02274k. Epub 2020 Mar 6.
Controlling the surface area, pore size and pore volume of microcapsules is crucial for modulating their activity in applications including catalytic reactions, delivery strategies or even cell culture assays, yet remains challenging to achieve using conventional bulk techniques. Here we describe a microfluidics-based approach for the formation of monodisperse silica-coated micron-scale porous capsules of controllable sizes. Our method involves the generation of gas-in water-in oil emulsions, and the subsequent rapid precipitation of silica which forms around the encapsulated gas bubbles resulting in hollow silica capsules with tunable pore sizes. We demonstrate that by varying the gas phase pressure, we can control both the diameter of the bubbles formed and the number of internal bubbles enclosed within the silica microcapsule. Moreover, we further demonstrate, using optical and electron microscopy, that these silica capsules remain stable under particle drying. Such a systematic manner of producing silica-coated microbubbles and porous microparticles thus represents an attractive class of biocompatible material for biomedical and pharmaceutical related applications.
控制微胶囊的表面积、孔径和孔体积对于调节其在催化反应、输送策略甚至细胞培养等应用中的活性至关重要，但使用传统的体相技术很难实现这一目标。在这里，我们描述了一种基于微流控的方法，用于形成单分散的、具有可控尺寸的二氧化硅涂层微米级多孔胶囊。我们的方法涉及到气-水-油乳液的生成，以及随后的二氧化硅的快速沉淀，这会在被包裹的气泡周围形成中空的二氧化硅胶囊，具有可调的孔径。我们证明，通过改变气相压力，我们可以控制形成的气泡的直径以及被包裹在二氧化硅微胶囊内的内部气泡的数量。此外，我们还进一步利用光学和电子显微镜证明，在颗粒干燥的情况下，这些二氧化硅胶囊仍然保持稳定。因此，这种系统地生产二氧化硅涂层微泡和多孔微颗粒的方法为生物医学和制药相关应用提供了一种有吸引力的生物相容性材料。
