Amplification of biomolecular interactions using liquid crystals and nanostructured surfaces

The research described in this thesis investigates the orientational response of nematic liquid crystals to target proteins on surfaces that are functionalized with nanometer-scale topography and specific chemistry for the capture of target proteins. The investigations presented in this thesis are organized into three parts.; The first part of the thesis focuses on the engineering of mixed self-assembled monolayers (SAMs) formed on films of gold deposited at oblique angles. SAMs presenting nitrilotriacetic acid groups chelated to Ni2+, are used to specifically capture histidine-tagged proteins. A background of ethylene glycol terminated thiols prevents the non-specific adsorption of proteins. Using this experimental system, we investigated the orientational ordering of nematic liquid crystals in the presence histidine-tagged proteins captured on these surfaces, as well as complexes formed by the histidine-tagged proteins and antibodies.; The second part of this thesis focuses on the design of surfaces such that affinity microcontact printing can be combined with the use of liquid crystals to report targeted proteins within a mixture. Target proteins are captured onto affinity stamps and then transferred to solid surfaces with defined chemistry and nanometer-scale topography. The orientational response of liquid crystals to captured proteins on these surfaces is investigated.; The third part of this thesis focuses on investigations that sought to advance our understanding of how the nanometer-scale topography of surfaces dictates that orientational response of liquid crystals to captured proteins. These studies employed two methods to fabricate surfaces with nanometer-scale topography. First, the deposition of gold films at oblique angles onto glass substrates was used to form anisotropic nanometer-scale topography and structure that uniformly orients nematic liquid crystals. We demonstrate that the fabrication of gold films that vary in the angle of deposition can screen a range of topography and structure for enhanced protein detection. Second, silicon substrates with well-defined nanometer-scale topography are fabricated by advanced lithographic methods. By tailoring the height and period of the topography to the size of proteins, we test several propositions regarding the manner by which the nanometer-scale topography of surfaces influences the orientational response of liquid crystals to captured proteins.