SiO2-Decorated Parylene C Micropillars Designed to Probe Cellular Force

Living cells sense and respond to mechanical signals through specific mechanisms generating traction force. The quantification of cell forces using micropillars can be limited by micropillar stiffness, technological aspects of fabrications, and microcontact printing of proteins. This paper develops the new design of SiO2/Parylene C micropillars with an aspect ratio of 6 and 3.5 and spring constant of 4.7 and 28 mu N mu m(-1), respectively. The upper part of micropillars is coated with a 250 nm layer of SiO2, and results confirm protein deposition on individual micropillars via SiO2 interface and non-adhesiveness on the micropillars' sidewalls. Results show an absence of cytotoxicity for micropillar-based substrates and a dependence on its stiffness. Stiffer micropillars enhance cell adhesion and proliferation rate, and a stronger cellular force of approximate to 25 mu N is obtained. The main contribution of SiO2/parylene C micropillars is the elimination of the step involving the fabrication of polydimethylsiloxane stamp because the array enables covalent binding of proteins via SiO2 chemistry. These micropillars stand on Si wafer and thus, any warping of underlying polymer membrane does not have to be considered. Additionally, SiO2/parylene C micropillars can broaden the range of stiffer substrates to be probed by cells.