Reactive polymer coatings: A first step toward surface engineering of microfluidic devices

We report fabrication, characterization, and use of micro-fluidic analysis devices containing surface-immobilized cell-capturing molecules. Amino-terminated biotin ligands are immobilized onto the luminal surface of a microdevice and effectively support self-assembly of proteins, antibodies, and mammalian cells. For this purpose, chemical vapor deposition (CVD) polymerization is used to functionalize PDMS-made microfluidic devices with poly-[para-xylylene carboxylic acid pentafluorophenolester-co-para-xylylene]. The resulting reactive coating shows excellent adhesion when deposited in thin films (∼100 nm, and the distribution of the pentafluorophenol ester groups is reasonably uniform within the microchannel inner surface, as examined by fluorescence microscopy. The utility of these devices for cell-based bioassays is demonstrated by monitoring the concentration-dependent effect of the disintegrin echistatin on cell adhesion. The described assay format could be relevant to clinical research in various fields, including angiogenesis research.