(538a) Environmentally Responsive Liquid Crystal Emulsions with Long-Term Colloidal Stability and Enhanced Sensitivity to Amphiphilic Analytes

Liquid crystal (LC)-in-water emulsions provide a versatile platform for designing droplet-based sensors that can detect and report the presence of amphiphilic analytes in aqueous environments. The practical utility and potential application of LC emulsions in these contexts is limited, however, because the bare LC droplets that comprise them are not colloidally stable for prolonged periods. This presentation will describe our recent studies aimed at designing LC droplet-based sensors with improved colloidal stability, tunable sensitivity, and selectivity to aqueous amphiphilic analytes. Our approach makes use of so-called “Pickering emulsions” created by the adsorption of nanoparticles to aqueous/LC droplet interfaces. We designed Pickering LC emulsions that remain colloidally stable for at least three months. The nanoparticle-stabilized LC droplets in these emulsions respond to and report on the presence of aqueous amphiphiles (e.g., surfactants, lipids), as evidenced by LC ordering transitions in the nanoparticle-decorated LC droplets that are similar to those observed in bare-droplet LC emulsions and can be readily observed and quantified, in real time, using polarized light microscopy. This approach also provides means to tune the sensitivities of the nanoparticle-stabilized LC droplets to amphiphilic analytes. Overall, our results demonstrate that Pickering stabilization provides a useful strategy to substantially improve the colloidal stability and shelf-life of LC emulsions and tune the sensitivities of the nanoparticle-stabilized LC droplets, thus increasing the potential practical utility of these droplet-based sensors as platforms for the detection and reporting of aqueous analytes.