Birefringence of flow-assembled chitosan membranes in microfluidics
Birefringence of flow-assembled chitosan membranes in microfluidics
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DOI：
10.1088/1758-5090/aa786e
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发表时间：
2017-09-01
期刊：
影响因子：
9
通讯作者：
Luo, X.
中科院分区：
文献类型：
--
作者：
Li, K.;Correa, S. O.;Luo, X.
微流体中的生物聚合物膜组装为组装期间和之后的生物分子和细胞相互作用提供精确的空间和时间分辨率。控制分子通过生物制造膜的运输需要微观结构表征。本研究首次研究了微流体环境中流动组装的壳聚糖膜的双折射，以及pH和流速对膜的微取向的影响。使用用于透射定量偏振光显微镜的de Senarmont补偿器来定量所形成的膜的光学各向异性。在微流控网络中的小孔径内，利用壳聚糖和海藻酸盐溶液的各种流动和pH条件，生物制造壳聚糖膜。所测量的光学延迟和平行性指数清楚地表明，流动组装膜的微观结构组织良好，并沿沿着壳聚糖流动的方向排列。光学延迟随藻酸盐溶液的pH值显著增加，但对生物纤维化过程中聚合物溶液的流速变化不太敏感。还确定了无论膜中的分子密度如何，双折射信号在膜生长方向上显著下降。讨论了微取向的机理，认为是剪切流动引起的分子解缠绕。我们设想，目前的研究铺平了道路，以进一步了解和积极操纵流动组装膜的微观结构，为广泛的芯片实验室应用。
Biopolymer membrane assembly in microfluidics offers precise spatial and temporal resolution for biomolecular and cellular interactions during and after assembly. Control over molecular transport across the biofabricated membranes requires microstructural characterization. This study investigates, for the first time, the birefringence of chitosan membranes assembled with flow in a microfluidic environment, and the effects of pH and flow rate on the membrane's micro-alignment. The optical anisotropy of the formed membranes was quantified using a de Senarmont compensator for transmitted quantitative polarized light microscopy. The chitosan membranes were biofabricated within a small aperture in a microfluidic network with various flow and pH conditions of chitosan and alginate solutions. The measured optical retardance and parallelism index clearly indicate that the microstructure of the flow-assembled membrane was well organized and aligned along the direction of chitosan flow. Optical retardance increased significantly with the pH of the alginate solution, but was less sensitive to the variation of the flow rates of the polymer solutions during the biofabrication process. It was also determined that the birefringence signal dropped significantly across the membrane growth direction regardless of the molecular density in the membrane. The mechanism of the micro-alignment was discussed, which was presumably due to the molecular un-wrapping by shear flow. Weenvision that the current study paves a path to further understand and actively manipulate the microstructure of flow-assembled membranes for broad lab-on-a-chip applications.