Bile acid–surfactant interactions at the liquid crystal/aqueous interface

Abstract

The interaction between bile acids and surfactants at interfaces plays an important role in fat digestion. In this paper, we study the competitive adsorption of cholic acid (CA) at the sodium dodecyl sulfate (SDS)-laden liquid crystal (LC)/aqueous interface formed with cyanobiphenyl (nCB, n = 5-8) and the mixture of 5CB with 4-(4-pentylcyclohexyl)benzonitrile (5PCH). We find that the critical concentration of CA required to displace SDS from the interface linearly decreases from 160 μM to 16 μM by reducing the alkyl chain length of nCB from n = 8 to n = 5 and from 16 μM to 1.5 μM by increasing the 5PCH concentration from 0 wt% to 19 wt% in the 5PCH-5CB binary mixture. Our results clearly demonstrate that the sensitivity of 5PCH-5CB mixtures for monitoring the interaction between CA and SDS at the LC/aqueous interface can be increased by one order of magnitude, compared to 5CB.

Control of Director Fields in Phospholipid-Coated Liquid Crystal Droplets

“…Past studies have demonstrated that for LC droplets the anchoring of the LC is dependent on many factors. These include the structure and density of the surfactant coating, the interfacial anchoring energy, a size-dependent effect relating to the elasticity of the LC, and the strength of interactions between LC molecules in the bulk . Experiments have shown that the elastic energy, F E , scales linearly as F E ∼ KR for a droplet of radius R , whereas the surface energy F s scales as F s ∼ WR 2 where W is an anchoring energy coefficient that controls the orientation of LC molecules at a surface.…”

12.4: A Liquid Crystal Biosensor for Liver Diseases

“…The LC used in the biosensors is a mixture of 18.93 wt % of 5PCH and 81.07 wt % of 5CB. We have shown in our recent publications that the mixed LC-based biosensor gives a lower detection limit for screening bile acids in PBS solution [19]. We find that the LC based biosensors show no response to these potential species.…”

“…In a previous publication [18,19], we showed that the detection limit for cholic acid (one type of bile acids) depends on the nature of surfactants used for forming the surfactant-laden LC/aqueous interface. The influence of the LC structures including chain length, polar group, and core structure on the detection limit for cholic acid has been studied.…”

Recent Advances in Adaptive Liquid Crystal Lenses

“…By adding an analyte that allows some kind of binding with the LC or the alignment surface, the LC orientation can be strongly affected by the presence of microparticles such as bacteria, introducing disorder into the area around the binding zone. Hence, LC can make unique optical probes for imaging the molecular ordering and chemical patterns of organic surfaces and sensing the chemical reactions such as enzymatic reactions, DNA hybridization, ligand-receptor bindings, and peptide-lipid interactions at the LC/aqueous interface [37,38]. The same concept is also exploited in other fields, such as security, using LC devices based on different alignments that boost them with particular characteristics of visualization [39].…”