Bioanalytics of microvesicles based on liquid crystals

The research described in this thesis studies the interactions between model and cell-derived phopholipid vesicles with interfaces of nematic liquid crystals (LCs). This research is motivated by the potential utility of LC-based platforms for detection of microvesicles shed by cells, which has been recognized as important in a broad spectrum of cancer-related context.;The first section of this thesis describes ordering transitions in nematic LCs induced by the capture of phospholipid vesicles at protein-functionalized solid surfaces via specific recognition events. Our results are consistent with a physical picture in which the aliphatic side chains of the phospholipids captured at these surfaces (as either vesicles or planar multilayer assemblies) dictate the ordering of the LC.;The second section of this thesis includes studies of specific binding of vesicles to protein-decorated aqueous-LC interfaces that are amplified into continuous orientational transitions in the LC. The dynamics of these transitions were significantly faster than that observed in the absence of the specific binding events. We demonstrate that displacement of the proteins from the interface by captured vesicles is necessary for the LC ordering transition to be observed.;The third section of this thesis builds on the fundamental insights into the origins of dynamical anchoring transitions at aqueous-LC interfaces that reflect the presence of sub-optical heterogeneity at complex protein-lipid interfaces. We also measured the dynamics of LC anchoring transitions to be accelerated with increasing ligand concentration in the vesicles.;The fourth section of this thesis describes a LC droplet-based method for detection of cell-derived microvesicles captured specifically by magnetic beads presenting target antibodies. Using this technique, antigen binding and microvesicles capture can be detected via extraction of lipid components of microvesicles which trigger ordering transitions within LC droplets from a bipolar to a radial configuration. Rapid read out of the response of LC droplets was achieved using scatter plots by flow cytometry.;The research in this thesis, when combined, provides advances in principles based on protein-decorated LC interfaces that might be exploited in a range of contexts, including the design of stimuli-responsive materials and analytic systems.