Department of Chemistry, University of Rome La Sapienza, P. le A. Moro 5, 00185 Rome, Italy.
Langmuir. 2013 Jan 8;29(1):82-91. doi: 10.1021/la303788z. Epub 2012 Dec 19.
In this article, we have exploited a microfluidic foaming technique for the generation of highly monodisperse gas-in-liquid bubbles as a templating system for scaffolds characterized by an ordered and homogeneous porous texture. An aqueous poly(vinyl alcohol) (PVA) solution (containing a surfactant) and a gas (argon) are injected simultaneously at constant flow rates in a flow-focusing device (FFD), in which the gas thread breaks up to form monodisperse bubbles. Immediately after its formation, the foam is collected and frozen in liquid nitrogen, freeze-dried, and cross-linked with glutaraldehyde. In order to highlight the superior morphological quality of the obtained porous material, a comparison between this scaffold and another one, also constituted of PVA but obtained with a traditional gas foaming technique, was carried out. Such a comparison has been conducted by analyzing electron microscopy and X-ray microtomographic images of the two samples. It turned out that the microfluidic produced scaffold was characterized by much more uniform porous texture than the gas-foaming one as witnessed by narrower pore size, interconnection, and wall thickness distributions. On the other side, scarce pore interconnectivity, relatively low pore volume, and limited production rate represent, by now, the principal disadvantages of microfluidic foaming as scaffold fabrication method, emphasizing the kind of improvement that this technique needs to undergo.
本文利用微流控发泡技术制备了高度单分散的气-液气泡，作为具有有序、均匀多孔结构支架的模板系统。将含有表面活性剂的水溶液和气体（氩气）以恒定流速同时注入到流聚焦装置（FFD）中，在其中气体线流分裂形成单分散气泡。气泡形成后，立即在液氮中收集并冷冻、冻干，然后用戊二醛交联。为了突出所得到的多孔材料的优异形态质量，对该支架与另一个由 PVA 但采用传统气体发泡技术制备的支架进行了比较。通过分析两种样品的电子显微镜和 X 射线微断层图像进行了比较。结果表明，微流控产生的支架的多孔结构比气体发泡的支架更均匀，表现为孔径、连通性和壁厚分布更窄。另一方面，目前微流控发泡作为支架制造方法的主要缺点是孔连通性差、孔体积相对较低和生产速率有限，这强调了该技术需要改进的方面。
