Heads or tails: investigating the effects of amphiphile features on the distortion of chiral nematic liquid crystal droplets

Abstract

Liquid crystal-based sensing has fast become a growing field, harnessing the sensitivity of liquid crystals to their surroundings to provide information about the analytes present, including surface-active amphiphiles such as...

Biosensing with Oleosin-Stabilized Liquid Crystal Droplets

“…In NLC droplets, we can neglect the T terms in Equations 1 and 2, so we need only look at the difference between the splay and bend conformations. In contrast, previous work has shown that chiral nematics in general do show a greater sensitivity to confinement-and surface-driven effects [66,67], and we also cannot neglect the T terms; in fact, T tan 6 = T nor ,a n dp a r t i c u l a r l yu p o nt h ea d s o r p t i o no f amphiphiles [27]. The consequence of this is likely that the energy barrier to switch between the two configurations in the chiral nematic (with the normally aligned system being lower energy) is much lower than for the nematic, making the CLC more susceptible to a change of alignment.…”

“…However, this would require a different platform or a different added stabilizer to enable the CLC to optimally function as a sensor. Since the CLC is directly switched by the oleosins and we have shown in previous work that we can differentiate between different amphiphiles using a color channel analysis [26,27], further investigation could establish if we can differentiate between proteins with different lengths of amphipathic helices and hydrophilic "wings", an important aspect of being able to identify their biological role in cells.…”

“…Most reported sensing applications use nematic liquid crystals (NLCs), ordered fluid phases that often function based on a change of the LC alignment [2,17,18] or loss of the LC phase altogether [5,7,14,15,19]. Increasing attention has been paid to sensing with chiral nematic liquid crystals (CLCs), which can exhibit brilliant structural color reflection [20][21][22][23] that can additionally provide information about the stimuli causing the change, whether it be temperature [9,11,12], strains [8,24], or adsorption of amphiphiles [21,[25][26][27].…”

“…Recently, droplets [21,[25][26][27] and shells [34][35][36] of LCs have attracted increasing attention as sensors, addressing some of the challenges (particularly fragility) associated with the use of thin films. Both LC droplets and shells have quite strong curvature-and interfacial tension-driven effects and are usually stabilized by dilute solutions of poly(vinyl alcohol) (PVA), an amphiphilic polymer which preferentially adsorbs at the LC/water interface [37, 38][6, 35, 39-42].…”

Biosensing with Oleosin‐Stabilized Liquid Crystal Droplets

“…[ 5,7,15,16,20 ] Increasing attention has been paid to sensing with chiral nematic liquid crystals (CLCs), which can exhibit brilliant structural color reflection [ 21–24 ] that can additionally provide information about the stimuli causing the change, whether it be temperature, [ 10,12,13 ] strains, [ 8,25 ] or adsorption of amphiphiles. [ 23,26–28 ]…”