(640f) Chemical Vapor Deposition within Confined Microgeometries
The development of generally applicable protocols for the surface modification of complex substrates has emerged as one of the key challenges in biotechnology. Recently, we reported a widely applicable surface modification approach based on chemical vapor deposition (CVD) polymerization to deposit reactive coatings on the luminal surface of open PDMS-based microchannels.  In addition to being compatible with the requirements of biological assays, these coatings provide a designable interlayer that is stable under the conditions of bioassays. The question that whether the concept of CVD polymerization is expandable to the coating of complex microgeometries with high aspect ratios prior to assembly has been addressed. Herein, we demonstrate the usefulness of chemical vapor deposition polymerization for surface modification in confined microgeometries with both, non-functionalized and functionalized poly(p-xylylenes). For a diverse group of polymer coatings, homogenous surface coverage of different microgeometries featuring aspect ratio as high as 37 has been demonstrated based on optical microscopy and imaging X-ray photoelectron spectroscopy (XPS). In addition, cross-section height analysis of deposited polymer footprints were examined by atomic force microscopy (AFM) and imaging ellipsometry indicating continuous deposition throughout the entire microchannels. In addition, the ability of reactive coatings to support chemical binding of biological ligands, when deposited in previously assembled microchannels, is demonstrated, verifying the usefulness of the CVD coatings for applications in micro/nano-fluidics, where surface modifications with stable and designable biointerfaces are essential. The fact that reactive coatings can be deposited within confined microenvironments exhibits an important step towards new device architectures with potential relevance to bioanalytical, medical, or ?BioMEMS? applications.
References:  Lahann, J.; Balcells, M.; Lu, H.; Rodon, T.; Jensen, K. F.; Langer, R. Analytical Chemistry 2003, 75, 2117-2122.  Chen, H.-Y.; Lahann, J. Analytical Chemistry 2005, 77, 6909-6914.  Chen, H.-Y.; Elkasabi, Y.; Lahann, J. Journal of the American Chemical Society 2006, 128(1), 374-380.