High-Density, High Aspect Ratio Silicone Post Arrays for Magneto Optical Biosensing and Targeted Cell Capture

Abstract

We have developed a dense microarray of tall, flexible silicone posts which has strong potential for use in magento-optical biosensing applications or as high-surface-area devices for cell capture. The posts in the array are 25 μm tall by 500 nm in diameter (AR: ∼50) with densities ranging from of 2e6 to 2e7 posts/cm2 (2 to 7 microns average spacing). The posts are treated with a hydrophilic silicone surfactant which renders them stable against lateral collapse in fluid suspension. In addition, the posts can be fabricated using a magnetic-nanoparticle / silicone composite to produce a magnetically actuatable array.The post array is fabricated by filling the pores of a polycarbonate track-etched membrane with liquid silicone or magnetic silicone composite. The filled membrane is placed on a glass substrate and the silicone is cured, after which the polycarbonate membrane is removed by dissolution. The surfactant treatment is applied during dissolution, allowing the completed array to be resuspended in a variety of solvents.Both the active (magnetic) and passive silicone arrays provide a very large surface area which may be well-suited for use in a variety of biosensing applications, such as magnetic-bead-based sandwich assays. In addition, the chaotic flow produced within a magnetically-actuated array dramatically increases opportunities for contact with targeted materials such as circulating tumor cells in a cell-capture device.