Micro-patterning of phosphorylcholine-based polymers in a microfluidic channel

This paper describes a method for producing patterned biomimetic phosphorylcholine-based polymers inside a microfluidic channel using a dry film mask made of poly(p-xylylene) (Parylene). We applied a commercially available 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer to a glass substrate to prevent non-specific binding of proteins and cells. We then deposited a Parylene film onto the MPC polymer-grafted glass substrate. Oxygen (O2) plasma was used to remove the Parylene and the MPC polymer from certain regions. The remaining Parylene film protected the underlying polymer and revealed the patterned MPC layer when it was removed. This technique produces patterns of the MPC polymer (i) without the use of chemicals that may damage the polymer, (ii) at high resolution over a large area, and (iii) that can be placed inside a microfluidic channel when combined with a polydimethylsiloxane (PDMS) microchannel. We achieved pattern sizes as small as 3 μm for the etched regions and 1.5 μm for spacing of the MPC polymer. Using a substrate with patterned MPC polymer, we have demonstrated the pattern of endothelial cells at the single-cell level, and the array and assay viability of fibroblast cells inside a microfluidic channel.