Poster Presentations
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Application of cholesteric liquid crystal for sensor
Hyeon-gyu Lee, Master degree student, Kyungpook national university
The cholesteric nematic liquid crystal (CLC) droplets consisting MLC-2132 (nematic liquid crystal, Merck) and CB15 (chiral dopant, Synthon) were prepared by a microfluidic method with aqueous solutions of polyvinyl alcohol and sodium dodecylsulfate in the continuous phase, which cause parallel and perpendicular anchorings of LC in the droplet, respectively. The helical structure (observed through polarized optical microscopy) was strongly dependent on the used surfactant. The CLC droplet with parallel and perpendicular anchorings had concentric rings with their centers at the center and off the center of the droplet, respectively. These two helical structures were reversibly changed each other by exposing the LC droplet (prepared in one surfactant) in the other surfactant solution. This structural change was applied to the biosensor by employing the pH-responsive polyelectrolyte on the surface with a block copolymer consisting of liquid crystal and polyelectrolyte blocks as a surfactant.
Novel biosensors using liquid crystal droplets decorated with functional polyelectrolytes
Soo-Young Park, Professor, Kyungpook National University
5CB microdroplets coated with PAA-b-LCP and PNIPAM-b-LCP were successfully made via microfluidics. Their functionalized surfaces at the water/5CB interface were examined for protein detection which could be easily visualized with an optical microscope under crossed polarizers by the radial to bipolar configurational change. The GOx and urease were immobilized on the PAA chains for glucose and ureas detection, respectively, by a EDC/NHS reaction. The H+ and OH- ions released by the GOx and urease reactions of glucose and urea, respectively were detected by the radial to bipolar (or vice versa) configurational change of 5CB droplets. This study demonstrated a simple approach for the development of a liquid crystal-based sensor for label-free detection of proteins, glucose, and urea which may have diverse applications in various biomedical fields
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