Coupling liquid crystal phase transitions with aptamer selectivity for biomolecular sensing

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PI: Tu, Raymond Proposal Number: 1605904The goal is to create an inexpensive and flexible biosensor using biological materials of special properties for the rapid recognition of harmful toxins and cancer biomarkers. Liquid crystals, the same structures that are in TVs and watches, can be used as an ultra-sensitive switch for visualizing the sensing phenomena. Taken together, a new device is expected to be created for the rapid detection of numerous disease biomarkers.This work will investigate a low-cost label-free sensing technology that focuses on analytes that can quickly diagnose illnesses and toxins prevalent in impoverished populations. The researchers aim to accomplish this by combining the cooperative phase transitions of liquid crystals with the flexibility of aptamer-based analyte binding. Liquid crystal based biosensors are inexpensive and sensitive, but the label-free application of the homeotropic to planar phase change requires a change in the interfacial packing of the nematic mesogen, restricting applications to a narrow range of targets. In contrast, aptamers possess the ability to selectively bind to a wide range of analytes, and the ability to quickly evolve new targets using Systematic Evolution of Ligands by EXponential (SELEX) enrichment has made the nucleic acid recognition elements a popular topic in the sensing community. Still, the challenge remains to translate this easily evolvable selectivity into an inexpensive label-free "aptasensor." The goal of this work is to examine the fundamental interfacial science and aptamer sequence space needed to robustly couple the nematic liquid crystal-aqueous interface with aptamer selectivity and sensitivity. Our approach for creating a "generalizable" aptamer-liquid crystal system investigates in the proposed work, four fundamental aspects of the sensing system. (1) Develop a quantitative methodology for the evaluation of competitive adsorption to the nematic liquid crystal-aqueous interface. (2) Measure and model the change in surface energy as the liquid responds to surfactants, unbound aptamers and bound aptamers. (3) Determine the rate limiting steps for realistic sensor design, where the kinetics of the phase transition should not require protracted diffusive or adsorption times. (4) Develop tools for the evolution of both the aptamer selectivity as well as the aptamer interaction with the liquid crystal and surfactants.