DescriptionHarnessing the sensing potential of liquid crystals (LCs) into sensors to detect temperature, stresses, harmful gases, and other contaminants of interest has fast become a topic of interest. One platform is using LCs in responsive aqueous emulsions of droplets and shells; however, owing to the extremely high interfacial tension between an LC and water, some amphiphilic interfacial stabilizer is necessary. Most surfactants are inadequate for use due to them readily switching the alignment of the LC. The most commonly used stabilizer, poly(vinyl alcohol) (PVA), sufficiently stabilizes the LC–water interface without switching, but at the cost of a severe decrease in sensitivity of the interface to further amphiphiles, particularly large, bulky ones such as lipids. An alternative is the use of an amphiphilic protein for stabilization, and one promising candidate can be found in oleosins, proteins derived from nut and seed oils: these often are smaller in size than PVA while still showing both a strong amphiphilic character that could make them amenable to sensing and possibly better
biocompatibility for eventual applications.
In this work, we investigate the use of these oleosins to stabilize liquid crystal droplets and their subsequent use for biological sensing. We find that the oleosins, at molar concentrations comparable to PVA, are capable of stabilizing the water–nematic LC interface over long durations of time (on the order of months). The oleosins readily localize at the LC–water interface without inducing an alignment switch, as seen in, and the interface is responsive to the later introduction of amphiphiles at a greater sensitivity than we observe in droplets stabilized with PVA. In contrast, in a variety of chiral nematic LC phases, an alignment change was directly induced by the oleosins at the same concentrations used to stabilize the non-chiral nematics. This could possibly be a consequence of residual lipids remaining from the oleosin purification process and the higher sensitivity of chiral nematic LCs to surfactants compared to non-chiral LCs; however, the sensitivity to oleosins is quite pronounced, serving as a basis for oleosin sensing. These findings can be further
used in the development of sensing platforms, giving us clues to sensitivity and specificity improvements of LC-based sensors.
|Period||10 Jul 2023 → 14 Jul 2023|
|Event title||16th European Conference on Liquid Crystals (2023)|