Isotropically Etched Silicon Microarrays for Rapid Breast Cancer Cell Capture

In this paper, we describe design and fabrication of 3-D silicon microarrays consisting of a wide range of isotropically-etched concave cavities for cell-capturing applications. The microarrays supported rapid and efficient capture of metastatic human breast cancer cells (MDA-MB-231) from single-cell suspensions. Furthermore, the captured cells adhered and were retained within the etched cavities for at least 72 h. Cavity spacing of 30–50
$\mu{\rm m}$
was most suitable for capture of the cells within microwells. Cell capture was evident within 1 min and was essentially complete by 20–30 min. Capture of 10
$\mu{\rm m}$
beads proceeded with a similar time frame and efficiency. Cell capture was 80%–90% efficient and was independent of cavity diameters tested: 35, 60, 70, and 100
$\mu{\rm m}$
. The depth of the microwells ranged from 28 to 54
$\mu{\rm m}$
. For single-cell capture, the 35
$\mu{\rm m}$
diameter cavity was optimal. The larger cavities contained 3–10 cells and were better suited for applications sensing cell proliferation, cell-cell interactions, stem cell differentiation, and drug responsiveness. The proposed silicon microarrays did not require any chemical coating or surface modification to support micro co-cultures of normal human breast epithelial cells (MCF10A) and MDA-MB-231 after cell trapping. This paper demonstrates that the silicon microarrays efficiently capture individual human breast cancer cells from a mono-culture suspension and in a mixture of excess MCF10A. Therefore the developed silicon platform is suitable for efficient detection and sensing of individual human breast cancer cells.