A Silicon-Based Porous Thin Membrane as a Cancer Cell Transmigration Assay

This paper presents a novel microfabricated Boyden chamber in silicon with well-defined pore sizes and controlled membrane thickness for cell migration analysis. The chip-based chamber is fabricated employing lithography and deep reactive ion etching techniques on a double-sided polished silicon wafer. The device contains micro-pores with a silicon oxide layer at the top and a deep microfluidic channel at the bottom, which is anodically-bonded to a glass wafer for sealing and facilitating the imaging and chemoattractant feeding. The applicability of the chip has been demonstrated through the distinct migratory behaviors of highly metastatic breast cancer cells, MDA-MB-231, through pores with 8 μm in diameter, 50 μm in spacing, and 30 μm in thickness. Employing the above technique, the membrane thickness variation among different chips was below 10%. Utilizing this micro-Boyden chamber device, we have shown that MDA-MB-231 cells migrated distinctively in higher rate than the cells which had gone through sphingosine kinase inhibitor drug treatment or no chemoattractant feeding over a course of 12 hours. Furthermore, we validated the performance of the micro-Boyden chamber by quantifying the migration rate of the cancer cells under different chemoattractant gradient profiles.