Surface anchoring of liquid crystals in contact with functionalized organic thin films

The research activities that are summarized in this dissertation aim to elucidate principles that permit the development of sensitive and quantitative analytical methods using liquid crystals to report the highly selective capture of biomolecular analytes at surfaces. These principles are based on the following past observations: (1) the orientations of liquid crystals near surfaces are sensitive to subtle changes in interfacial energy (10-9 J/m2 to 10-3 J/m2), (2) the binding of biomolecular analytes to surfaces can drive the reorientation of films of liquid crystals of thickness ≥100 mum, (3) changes in the orientations of liquid crystals can be measured using polarized light microscopy and (4) self-assembled monolayers formed from oligo(ethylene glycol)-terminated thiols that are supported on gold films form the basis of functional surfaces that can resist (or partially) resist the non-specific adsorption of proteins.; This thesis investigates: (I) the orientational behavior of a nematic liquid crystal in contact with oligo(ethylene glycol)-terminated self-assembled monolayers, (II) the amplification of protein-peptide binding events at oligo(ethylene glycol)-terminated self-assembled monolayers using liquid crystals, (III) the methodology to obtain a quantitative measurement of an intrinsic property of the liquid crystal/monolayer interface, i.e. azimuthal anchoring energy, (IV) the application of that methodology to quantify changes in the azimuthal anchoring energy of the liquid crystal/monolayer interface upon incremental addition of biomolecular analyte, (V) a low-cost surface preparation for the precise control of the out-of-plane alignment of liquid crystals over macroscopic distances and (VI) a preliminary study of using liquid crystals to image fibroblast cells that are adhered to functionalized oligo(ethylene glycol)-terminated self-assembled monolayers.; The results of this research, when combined, form the basis of quantitative analytical methods using liquid crystals for the study of biomolecular analytes that are present in complex biological fluids.