(334f) Pickering Liquid Crystal Emulsions for the Optical Detection of Amphiphilic Analytes

Liquid crystal (LC)-in-water emulsions provide useful platforms for designing droplet-based sensors capable of detecting a wide range of amphiphilic analytes, including surfactants and phospholipids, in aqueous environments. However, the practical application of LC emulsions has been limited by their poor colloidal stability, as bare (unprotected) LC droplets coalesce over time. In this presentation, we describe our recent efforts to address these challenges by using Pickering stabilization strategies consisting of surface-modified nanoparticles adsorbed at the LC-water interface to prevent LC droplet coalescence. This approach produces LC emulsions with improved shelf-life (i.e., LC emulsions that are stable for at least three months to one year). The stabilized LC droplets retain their responsiveness to amphiphilic analytes, as evidenced by LC ordering transitions observable via polarized light microscopy. Our results show that exposure to amphiphilic analytes such as synthetic surfactants, biosurfactants, and phospholipid vesicles leads to LC droplet configurational changes that are similar to those observed in bare (unprotected) LC droplets. We further demonstrate that the sensitivity and potential selectivity of the nanoparticle-stabilized LC droplets can be tuned based on the nanoparticle system used to prepare the Pickering LC emulsions. Overall, our results highlight Pickering-stabilized LC emulsions as promising platforms for the development of colloidally stable, tunable, droplet-based biosensors for aqueous analyte detection.