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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By using chemical vapor deposition (CVD) a range of substrates can be coated with a highly reactive polymer containing pentafluorophenol ester groups (see scheme). A biotin‐modified pattern is generated on the substrate by microcontact printing; such a pattern interacts specifically with fluorescein‐conjugated streptavidin and thereby the pattern becomes observable with fluorescence microscopy.

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Polymers based on functionalized [2.2]paracyclophanes are interesting interfaces for biomedical applications. A broader application of amino[2.2]paracyclophanes such as 1 and 2 has hitherto been limited by the lack of facile syntheses. Their effective synthesis has now been achieved in a two‐step procedure in high yields.

In the fields of surgery and regenerative medicine, it is crucial to understand the interactions of proteins with the biomaterials used as implants. Protein adsorption directly influences cell-material interactions in vivo and, as a result, regulates, for example, cell adhesion on the surface of the implant. Therefore, the development of suitable analytical techniques together with well-defined model systems allowing for the detection, characterization, and quantification of protein adsorbates is essential. In this study, a protocol for the deposition of highly stable, thin gelatin-based films on various substrates has been developed. The hydrogel films were characterized morphologically and chemically. Due to the obtained low thickness of the hydrogel layer, this setup allowed for a quantitative study on the interaction of human proteins (albumin and fibrinogen) with the hydrogel by Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D). This technique enables the determination of adsorbant mass and changes in the shear modulus of the hydrogel layer upon adsorption of human proteins. Furthermore, Secondary Ion Mass Spectrometry and principal component analysis was applied to monitor the changed composition of the topmost adsorbate layer. This approach opens interesting perspectives for a sensitive screening of viscoelastic biomaterials that could be used for regenerative medicine.

Whispering-gallery mode (WGM) microdisk lasers show great potential for highly sensitive label-free detection in large-scale sensor arrays. However, when used in practical applications under normal ambient conditions, these devices suffer from temperature fluctuations and photobleaching. Here we demonstrate that these challenges can be overcome by a novel referencing scheme that allows for simultaneous compensation of temperature drift and photobleaching. The technique relies on reference structures protected by locally dispensed passivation materials, and can be scaled to extended arrays of hundreds of devices. We prove the viability of the concept in a series of experiments, demonstrating robust and sensitive label-free detection over a wide range of constant or continuously varying temperatures. To the best of our knowledge, these measurements represent the first demonstration of biosensing in active WGM devices with simultaneous compensation of both photobleaching and temperature drift.