Design of a microfluidic device for chromatin immunoprecipitation (ChIP-on-chip)

Early detection of disease contributes significantly to treatment success and patient survival. Chromatin immunoprecipitation coupled with sequencing (ChIP-seq) was shown to be a suitable method for detecting various diseases, such as cancer, from small blood or tissue samples. However, ChIP is currently a multi-step benchtop assay, exploiting the surface area of microbeads for chromatin capture. Here we show the design of a microfluidic pillar chip with a surface area of 2000 mm², a pillar density of 200 pillars per mm² and a total volume of 56 µL. The pillar chip is fabricated in PDMS and modified with a silane-based surface chemistry to immobilize antibodies for chromatin capture. Chromatin binds specifically to the antibodies and is released and further purified on the pillar chip following the standard ChIP-protocol. By performing ChIP on a micro-scale level, we aim to improve chromatin capture efficiency due to the spatial vicinity of antibodies and target molecules. Furthermore, possibilities for operating the chip automatically are enhanced.