Development of a Liquid Crystal Biosensor for the Detection of Endotoxin McCamley, Maureen K. creator 2009 xv, 120 p. born digital Thesis (Ph.D.) -- Brown University (2009) Crawford, Gregory director Artenstein, Andrew director Artenstein, Andrew reader Tripathi, Anubhav reader Opal, Steven reader Zumer, Slobodan reader Brown University. Biomedical Engineering sponsor theses This dissertation describes translational research conducted to develop a rapid diagnostic for the detection of endotoxin using liquid crystal sensor technology. Due to the elastic nature of bulk nematic liquid crystal, small changes in surface anchoring at the interface between the liquid crystal sensor and the targeted biomolecule (endotoxin) are amplified, allowing optical detection through polarizing microscopy. Theoretical simulations (a phenomenological Landau-de Gennes model) were applied to understand and predict the behavior of the confined nematic. Simulated optical micrographs were compared with experiments to understand the nematic profiles and to control and optimize the sensor in a specific regime. Distinct optical patterns were detected when the sensor was exposed to air and to water. A structural transition in the nematic structure was observed, driven by changes in the anchoring strength at the open surface of the sensor. This change was leveraged and used to detect the presence of both a model surfactant and the targeted biomolecule at the open surface. The response of the sensor can be controlled by changing certain experimental parameters, such as the depth, aspect ratio, anchoring strength and nematic material. Isolated lipopolysaccharide (LPS) was detected in concentrations varying from 1 mg/mL to 10 ug/mL, giving a very strong and quantifiable response of the sensor. Liquid crystalsEndotoxinsBiomedical engineering RPB 20091218 engEnglish10.7301/Z0FQ9TVWIn CopyrightCollection is open for research.dissertations