We report fabrication, characterization, and use of microfluidic 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 (approximately 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.

We report a procedure for surface modification based on chemical vapor deposition polymerization of functionalized [2.2]paracyclophanes that is essentially substrate-independent. Poly(p-xylylene-2,3-dicarboxylic anhydride) and poly[p-xylylene carboxylic acid pentafluorophenolester-co-p-xylylene] are examined as templates for cell patterning. Both reactive coatings are deposited on poly(tetrafluoroethylene), polyethylene, silicon, gold, stainless steel, and glass and show excellent adhesion when deposited in thin films (ca. 100 nm) under optimized polymerization conditions. X-ray photoelectron spectroscopy and grazing angle infrared spectroscopy have been used to confirm chemical homogeneity in both cases. Reactive coatings are subsequently patterned by microcontact printing of an amino-terminated biotin ligand and serve as templates for layer-by-layer self-assembly. Streptavidin selectively binds to the biotin-exposing surface regions and allows surface confinement of a biotin-tethered antibody against α5-integrin. The specific interaction of this antibody with endothelial cells results in spatially directed deposition of mammalian cells. Fluorescence microscopy is used to verify accurate self-assembly at each step. Although both reactive coatings differ in how they chemically bind biomolecules, their ability to support formation of pattern by microcontact printing is similar.

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