Crystal Emulsions Research Articles

Responsive release of guest aqueous droplet in liquid crystal droplet assists the detection of organophosphorus using commercial pregnancy test strip

Here, we report a liquid crystal (LC) double-emulsion based system for organophosphorus (OPs) sensing by controllable release of guest aqueous droplets (GADs) cargo. First, double liquid crystal emulsion, water in liquid crystal in water (W/LC/W), with size between 4∼ 20 μm was prepared with GADs loaded at the center of liquid crystal droplet (LCD) through elasticity trap. The LCDs were monodispersed and response sensitively to amphiphilic surfactant with opposite charge. With the capability of ejecting GADs with human chorionic gonadotropin (hCG) as cargo located in LCD to continuous aqueous phase, responsive vehicles are obtained and applied in the repurposing of commercial pregnancy test strip (PTS). With hydrophobic alkyl chain and hydrophilic head, myristoylcholine (Myr) is a good amphiphilic surfactant to trigger the release of hCG, and substrate for the enzymatic hydrolysis of acetylcholine esterase (AChE). Provided with the inhibition effect of OPs to the hydrolysis ability of AChE, OPs correlate positively with the concentration of Myr, thus correlate well with the release of hCG in W/LC/W emulsion. Thus, OPs residue in river or food is readily visualized using commercial PTS.

Lyotropic liquid crystal emulsions of LAVR-289: Influence of internal mesophase structure on cytotoxicity and in-vitro antiviral activity

Emerging and reemerging viruses pose significant public health threats, underscoring the urgent need for new antiviral drugs. Recently, a novel family of antiviral acyclic nucleoside phosphonates (ANP) composed of a 4-(2,4-diaminopyrimidin-6-yl)oxy-but-2-enyl phosphonic acid skeleton (O-DAPy nucleobase) has shown promise. Among these, LAVR-289 stands out for its potent inhibitory effects against various DNA viruses. Despite its efficacy, LAVR-289s poor water solubility hampers effective drug delivery. To address this, innovative delivery systems utilizing lipidic derivatives have been explored for various administration routes. Submicron lyotropic liquid crystals (LLCs) are particularly promising drug carriers for the encapsulation, protection, and delivery of lipophilic drugs like LAVR-289.This study focuses on developing submicron-sized lipid mesophase dispersions, including emulsified L2 phase, cubosomes, and hexosomes, by adjusting lipidic compounds such as Dimodan® U/J, Lecithins E80, and Miglyol® 812 N. These formulations aim to enhance the solubility and bioavailability of LAVR-289. In vitro evaluations demonstrated that LAVR-289-loaded LLCs at a concentration of 1 µM efficiently inhibited vaccinia virus in infected human cells, with no observed cytotoxicity. Notably, hexosomes exhibited the most favorable antiviral outcomes, suggesting that the internal mesophase structure plays a critical role in optimizing the therapeutic efficacy of this drug class.

Study on the application and performance of liquid crystal emulsion system in sunscreen products

ABSTRACT Liquid crystal (LC) emulsion is a new emulsion system which has excellent application potential in the field of cosmetics. In this study, the LC emulsifier and traditional emulsifier were used to prepare the emulsions containing different types of sunscreen agents, respectively. The microstructure, sunscreen performance and rheological properties of the emulsions were studied systematically. The results showed that the formation of LC structure was not affected by sunscreen agents. LC structure can also enhance the sunscreen property of the emulsion as well as improve the sensory property. Further, we combined different sunscreen agents to prepare LC sunscreen emulsion. The sunscreen performance and repair effectiveness of emulsion were evaluated by human test. The results showed that LC sunscreen emulsion has an increased SPF value from 56 to 70 compared to non-LC sunscreen emulsion. Meanwhile, the LC structure also enhanced the moisturising properties of the emulsion, and the TEWL value of LC emulsion and non-LC emulsion was 67.4% and 96.5%, respectively. In addition, LC sunscreen emulsion has higher safety and better storage stability. In conclusion, this study provided the practical application of LC emulsion systems as well as the important guidance for developing excellent sunscreen emulsions.

Towards eco-friendly plant growth regulator: A robustly stable and efficient uniconazole emulsion based on onion-like lamellar liquid crystal

As a commonly water-based pesticide formulation, conventional Emulsions in Water (EWs) always suffer from demulsification in actual complex environments and burst release due to their thermodynamic instability. The ecotoxicity and phytotoxicity caused by chemosynthetic adjuvants cannot be ignored. To address these issues, herein, using a soybean lecithin-based lamellar liquid crystal emulsion (LCE) as the carrier, we construct a robustly stable and low-toxicity EW with the “onion-like” bionic structure and achieve the efficient delivery of plant growth regulator (PGR) uniconazole (UZ). The hydrophobic UZ is firmly encapsulated within the orderly assembled Oil-in-Liquid Crystal-in-Water (O/LC/W) multilayers. This confinement endows UZ-LCE with robust stability, even while encountering disturbances such as dilution, shaking, and changes in pH, ions, and temperature. Furthermore, UZ-LCE exhibits enhanced wettability and affinity to foliar surfaces, as well as specific sustained-release ability. Owing to these superiorities of UZ-LCE, during two consecutive years of efficacy evaluations in cotton field experiments, UZ-LCEs administered through drip irrigation and foliar spray demonstrate remarkable enhancements in controlling excessive plant growth, increasing chlorophyll content, and boosting flower bud formation, surpassing the effectiveness of conventional EWs. UZ-LCE even outperforms commercial preparations (WP and SC) in balancing vegetative growth and reproductive growth, resulting in an 8.3% increase in yield. This research provides an innovative pesticide formulation with eco-friendly adjuvants, less organic solvent, and synergistic functionalities, which is prospective to be extended to other pesticide EWs and contribute to sustainable agriculture.

Construction and Properties of O/W Liquid Crystal Nanoemulsion.

Liquid crystal emulsion is a new type of emulsion, in which the emulsifier molecules are located at the oil/water (O/W) interface and form a long-range ordered and short-range disordered lamellar liquid crystal. The lamellar liquid crystal formed by the emulsifier is similar to the skin stratum corneum lipid structure, which enables it to have a broad application prospect in the fields of cosmetics, pharmaceuticals, etc. In this work, a liquid crystal nanoemulsion was obtained by passing a liquid crystal emulsion stabilized by hydrogenated lecithin and phytosterol combination through a microfluidizer. The microstructure of the prepared liquid crystal nanoemulsion was investigated experimentally by dynamic light scattering, transmission electron microscopy, and small-angle X-ray scattering. The results have shown that the nanoemulsion inherited the liquid crystal emulsion property, namely, the long-range ordered and short-range disordered lamellar structure still existed at the oil/water interface even though they underwent extrusion, friction, and acceleration. At the same time, the underlying mechanisms of the existence of lamellar liquid crystal between the oil phase and the water phase for the nanoemulsion were explored theoretically by molecular dynamics simulations. The simulation results elucidated that the hydrogenated lecithin and phytosterol combination improved the flexibility of the bilayer structure composed of emulsifiers. The bilayers were the basic structure units of lamellar liquid crystals, and thus, the improved flexibility of bilayers provided insurance for the existence of lamellar liquid crystals with larger curvature around the oil droplets. In addition, the applicable properties of liquid crystal nanoemulsion were studied, and the results have shown that the liquid crystal nanoemulsion presented better slow-release and moisturizing properties than traditional nanoemulsions due to the existence of multilayers between oil and water phases. This work not only provides necessary information for the development and effective application of liquid crystal emulsions but also is helpful for in-depth understanding the inner properties of lamellar liquid crystal at molecular level.

Dynamically reconfigurable complex liquid crystal emulsions

ABSTRACT Complex emulsions, containing liquid crystals (LCs) and immiscible oils such as fluorocarbon or silicone oils, present innovative functionalities in soft materials. These emulsions exhibit dynamic reconfiguration in droplet morphology and internal LC organisation, expanding applications in optics, sensing, and active matter. This review highlights the evolution and potential of LC-containing complex emulsions. Emphasis is placed on emulsions featuring dynamic and reversible morphological transformations and LC reorganisation, underpinning their suitability for tunable micro-lenses, chemical sensing, and biosensing. Nematic LCs within complex emulsions allow for topological defect-driven functionalization, attaching antibodies to induce substantial changes in the LC director field upon interfacial recognition events. This feature may facilitate the development of ultrasensitive chemical and biological sensors. Moreover, cholesteric LCs, through their selective reflection, enable the rapid and sensitive detection of foodborne pathogens. The controlled assembly of magnetic nanoparticles at interfaces illustrates advancements towards magnetic field-responsive and active colloids. Future perspectives include exploiting these properties for intelligent colloidal systems capable of autonomous behaviour, and furthering applications in dynamic photonic devices, high-security identification tags, and responsive lens systems.

Self-Timed and Spatially Targeted Delivery of Chemical Cargo by Motile Liquid Crystal.

A key challenge underlying the design of miniature machines is encoding materials with time- and space-specific functional behaviors that require little human intervention. Dissipative processes that drive materials beyond equilibrium and evolve continuously with time and location represent one promising strategy to achieve such complex functions. This work reports how internal nonequilibrium states of liquid crystal (LC) emulsion droplets undergoing chemotaxis can be used to time the delivery of a chemical agent to a targeted location. During ballistic motion, hydrodynamic shear forces dominate LC elastic interactions, dispersing microdroplet inclusions (microcargo) within double emulsion droplets. Scale-dependent colloidal forces then hinder the escape of dispersed microcargo from the propelling droplet. Upon arrival at the targeted location, a circulatory flow of diminished strength allows the microcargo to cluster within the LC elastic environment such that hydrodynamic forces grow to exceed colloidal forces and thus trigger the escape of the microcargo. This work illustrates the utility of the approach by using microcargo that initiate polymerization upon release through the outer interface of the carrier droplet. These findings provide a platform that utilizes nonequilibrium strategies to design autonomous spatial and temporal functions into active materials.

Optical anti-counterfeiting with cholesteric liquid crystal emulsions: preparation, properties, and applications

This review highlights recent advancements in cholesteric liquid crystal emulsions, focusing on their preparation, anti-counterfeiting applications, and future prospects. It also covers their role in information storage and encryption techniques.

Water in liquid crystal emulsion-based sensing platform for colorimetric detection of organophosphorus pesticide

Development of a simple and convenient method for the rapid detection of organophosphorus pesticides (OPs) is particular important for the safety of environmental water and agriculture products. In this work, the water/liquid crystal (W/LC) emulsion is obtained via dispersing an aqueous solution of sodium dodecyl sulfate (SDS) and peroxidase from horseradish (HRP) into a water-immiscible nematic LC and employed as a sensing platform for the detection of dichlorvos (2, 2-dichlorovinyl dimethyl phosphate, DDVP) that is a typical OP with acute toxicity. Remarkably, the stepwise release of the encapsulated cargo HRP from the W/LC emulsion can be triggered upon the addition of the cationic surfactant myristoylcholine chloride (Myr) due to the strong interfacial charge interactions with the anionic surfactant SDS. The released HRP induces an obvious color change of the overlaying bulk aqueous solution via the H2O2-HRP-TMB reaction system. As Myr can be enzymatically cleaved by AChE, the detection of AChE is fulfilled successfully. This approach is also employed to detect DDVP that can irreversibly inhibit the activity of AChE. This assay shows a linear response between the absorbance of the oxidized TMB solution and the DDVP concentration in the range of 0.001–10 μg/mL (R2 = 0.99). The limit of detection (LOD) and the limit of quantity (LOQ) of DDVP are determined to be 1.9 ng/mL and 6.3 ng/mL, respectively. In addition, this strategy also demonstrates excellent performance for the DDVP detection in real samples, the detection recovery rate of DDVP in water samples (lake water and tap water) and vegetables (tomatoes and cole) by this method is 88.0 % ∼112.6 %, the relative standard deviation (RSD) ≤ 7.5 %. These results suggest the W/LC emulsion-based sensing platform shows great potential for visual detection of DDVP in real samples. In conclusion, the proposed approach is scalable for practical application in food safety as well as environmental monitoring fields, and will provide promising solutions for the assay of pesticide residues.

Liquid Crystal Emulsions: A Versatile Platform for Photonics, Sensing, and Active Matter.

The self-assembly of liquid crystals (LCs) is a fascinating method for controlling the organization of discrete molecules into nanostructured functional materials. Although LCs are traditionally processed in thin film, their confinement within micrometre-sized droplets has recently revealed new properties and functions for the design of next-generation soft responsive materials. These recent findings have enabled a wealth of unprecedented applications in photonics (e.g., reflectors, lasing materials), sensing (e.g., detection of biomolecules, pathogens), soft robotics (e.g., micropumps, artificial muscles), and beyond. This minireview focuses on recent developments in the design of LC emulsions and highlights a variety of novel potential applications. We also offer perspectives on the opportunities and new directions towards the implementation of LC emulsions in future innovative technologies.

Liquid Crystal Emulsions: A Versatile Platform for Photonics, Sensing, and Active Matter

AbstractThe self‐assembly of liquid crystals (LCs) is a fascinating method for controlling the organization of discrete molecules into nanostructured functional materials. Although LCs are traditionally processed in thin films, their confinement within micrometre‐sized droplets has recently revealed new properties and functions, paving the way for next‐generation soft responsive materials. These recent findings have unlocked a wealth of unprecedented applications in photonics (e.g. reflectors, lasing materials), sensing (e.g. biomolecule and pathogen detection), soft robotics (e.g. micropumps, artificial muscles), and beyond. This Minireview focuses on recent developments in LC emulsion designs and highlights a variety of novel potential applications. Perspectives on the opportunities and new directions for implementing LC emulsions in future innovative technologies are also provided.

Production and Reconfiguration of Double Emulsions by Temperature Control.

Double emulsions are of great importance for both science and engineering. However, the production of multicore double-emulsion droplets is challenging and normally requires sophisticated microfluidic devices, which limits their availability to broader communities. Here, we propose a simple, precise, and scalable batch method for producing double emulsions with monodispersed multicores at milliliter per minute rates, using the most common means in laboratory, temperature. By rapidly cooling liquid crystal emulsions, the introduced temperature gradient around the emulsion droplets leads to the injection of monodispersed guest droplets to form double-emulsion droplets. The number of injected water droplets can be precisely controlled by adjusting the thermally induced mechanical force through the temperature difference and the cooling rate. In contrast to conventional microfluidic fabrication, this method processes all emulsion droplets simultaneously in a noncontact and in situ manner. Therefore, it has great flexibility, allows multiple processing of double emulsions of arbitrary shape, has good capacity for mass production, and offers excellent compatibility with technologies such as microfluidics. Finally, we demonstrate that temperature changes can also be used to release the inner droplets from the double emulsion. The proposed method offers a reversible tool for processing double emulsions with minimal cost and expertise and is applicable to droplet-based microsystems in materials science, photonics, sensors, pharmaceuticals, and biotechnology.

Laser Injection Technique for Liquid Crystal Droplets with Arbitrary Shape

We propose a simple and precise method for processing three-dimensional droplet structures of liquid crystal with arbitrary shapes. By irradiating liquid crystal emulsions with a laser beam, a photothermally induced Marangoni effect is introduced. This leads to the injection of water solution into the liquid crystal droplets. With the help of the elasticity of liquid crystal, the injected water solution spontaneously forms into monodispersed guest droplets which latterly self-assemble into branched droplet chains. This method enjoys great flexibility due to its non-contact and in-situ processing manner, allows the simultaneous and multiple processing of all liquid crystal droplets under the irradiation region, and offers excellent compatibility with technologies such as microfluidics. The proposed method is applicable in material science, photonics, and sensors.

Influence of the emulsifier on nanostructure and clinical application of liquid crystalline emulsions

Liquid crystals are appealing in pharmaceutical and cosmetic fields due to their unique structures that combine the properties of both liquid and solid states. Forming an emulsion into liquid crystals can be affected by a number of factors, including the emulsion composition and temperature. Changing the types and concentrations of surfactants could be another factor that affects liquid crystals. Currently, most liquid crystal research focuses on the nanostructure of liquid crystal systems without evaluating the efficacy of liquid crystals clinically. In this study, liquid crystalline emulsions made from camellia seed oil with four different surfactants (Olivem 1000, Polyaquol-2W, Nikkomulese LC, and Lecinol S-10 with Tween 80) were created. The liquid crystal emulsions were formulated in the form of oil-in-water (o/w) emulsions with Camellia oleifera seed oil serving as the main ingredient in the oil phase (10% w/w). All formulations exhibited liquid crystal characteristics with lamellar structures as determined by the polarized light microscopy and small-angle X-ray scattering with supporting data of the nanostructure from wide-angle X-ray scattering and differential scanning calorimetry (DSC). They all showed good stability under normal (room temperature) and accelerated conditions (4 °C and 40 °C) in long-term storage (6 months). Using the reconstructed human epidermis as a skin model, all formulations did not cause skin irritation. In the clinical trial, all formulations were able to reduce transepidermal water loss (TEWL) and increase skin hydration immediately after application. This lasted at least 10 h. All formulations showed distinct Maltese crosses under the polarized light microscope with a positive result for liquid crystals in wide angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS) methods. Moreover, among all formulations tested, Formulation D, which contained Lecinol S-10 and Tween 80 as emulsifiers, showed the most robust interaction between the surfactant and water molecules in the lamellar structure under DSC. The formulation was stable in long-term normal and accelerated conditions. Above all, Formulation D, which was formulated with Lecinol S-10 with Tween 80, had the best clinical result, was nonirritating to the skin, and can be used as a cream base in the pharmaceutical and cosmeceutical sectors.

Controlled release of microcargo from water-in-liquid crystal emulsions via interfacial shear induced by synthetic microstirrers.

Past studies demonstrated that the microcargo carrying aqueous droplets trapped in LCs through elastic stresses can be triggered to release by applying shear to LC-bulk interfaces. Herein, we report our investigations on the release mechanisms of such microcargo entrapped in aqueous droplets of W-in-LC emulsions via interfacial shear caused by the synthetic micro-stirrer microparticle assemblies of iron oxide particles rotated with a magnetic field. We show that a three fold control over the release rate of the tracer molecules is possible that have initial release rates of 14.3 ± 2.5 μg cm-2 h-1, 26.5 ± 3.4 μg cm-2 h-1, and 46.9 ± 4.6 μg cm-2 h-1 when the rotation of magnetic flux was 250, 500 and 1000 rpm, respectively. We measure the release rates to reduce to 5.4 ± 1.2 μg cm-2 h-1, 6.3 ± 0.7 μg cm-2 h-1, and 20.0 ± 3.2 μg cm-2 h-1 after 60 min of shearing at 250, 500 and 1000 rpm, respectively. We present evidence for the release mechanism resulting in such temporal release profiles that correlate with the magnitude of the shear applied to the interface, interfacial coverage of the microstirrers, and the creaming effect of the aqueous droplets doped with tracers. We also report that the influence of the interfacial density of the microparticles that showed an intermediate areal density is required to achieve a maximized release rate. Additionally, we found evidence of the influence of the droplet charge that critically determines the release. This study highlights the importance of the colloidal and interfacial phenomena in the release profiles of the dispersed droplets present in a LC medium.

Novel delivery system: a liquid crystal emulsion containing HSO crystals

The combination of strengthened lamellar liquid crystal at the oil-water interface and the HSO crystal network inside the droplet endowed the emulsion with excellent sustainable release property.

All-Aqueous Bicontinuous Structured Liquid Crystal Emulsion through Intraphase Trapping of Cellulose Nanoparticles.

Here, we describe the all-aqueous bicontinuous emulsions with cholesteric liquid crystal domains through hierarchical colloidal self-assembly of nanoparticles. This is achieved by homogenization of a rod-like cellulose nanocrystal (CNC) with two immiscible, phase separating polyethylene glycol (PEG) and dextran polymer solutions. The dispersed CNCs exhibit unequal affinity for the binary polymer mixtures that depends on the balance of osmotic and chemical potential between the two phases. Once at the critical concentration, CNC particles are constrained within one component of the polymer phases and self-assemble into a cholesteric organization. The obtained liquid crystal emulsion demonstrates a confined three-dimensional percolating bicontinuous network with cholesteric self-assembly of CNC within the PEG phase; meanwhile, the nanoparticles in the dextran phase remain isotropic instead. Our results provide an alternative way to arrest bicontinuous structures through intraphase trapping and assembling of nanoparticles, which is a viable and flexible route to extend for a wide range of colloidal systems.

Topological capillarity in a phase separated liquid crystal system

Emulsions of isotropic liquids have spherical phase boundaries. Liquid crystals have elastic forces associated with the director distortions and preferred boundary conditions that can also play a role in defining the phase boundary shape. Here we show a liquid crystal in liquid crystal emulsion where a chemically distinct guest phase resides in the topological disclinations of the host phase. These disclinations act as effective capillaries and various meniscus and droplet phenomena are observed. This “topological capillary emulsion” shows that additional forces associated with anisotropic molecules can play a critical role in determining the shape and properties of a phase boundary.

Evaluation of In Vitro Skin Permeation of Enzymatically Synthesized Phloridzin Acetates from Emulsions and Liposomes Dispersed in Gel

AbstractThis work aims to evaluate the effect of cosmetic formulations on the skin permeation of phloridzin acetates, therefore in vitro transdermal delivery of these bioactive compounds across Strat‐M membrane is investigated. The formulations tested are gel emulsion, oil in water emulsion (O/W emulsion), gel in oil emulsion, liquid crystal emulsion, and liposomes dispersed in gel. The release of esters from the O/W emulsion is diffusion‐controlled (n = 0.5), while release kinetics from gel‐based formulations depends on coupled diffusion and polymer relaxations effect (0.5 < n < 1). The highest values of effective diffusion coefficient are obtained after release from O/W emulsion (24.64 × 10−10 m2 min−1 for phloridzin acetate and 6.55 × 10−10 m2 min−1 for phloridzin diacetate). The lag phase lasting from 1 h (gel emulsion) to 5 h (liquid crystal emulsion) indicates that esters permeation is significantly affected by the formulation used. Formulations in which the water is continuous phase are the most appropriate carrier system for transdermal delivery of phloridzin esters. Additionally, liposomes are successfully applied as carrier systems for the controlled release of esters, although it should be noted that liposomes without cholesterol show remarkable stability (ζ = −43 mV) and homogeneity (polydispersity index = 0.198).Practical application: Phloridzin is a flavonoid glycoside that possesses many beneficial activities such as antioxidant, UV‐protecting, and anti‐inflammatory activity, so the use of this flavonoid and its derivatives in numerous cosmetic and pharmaceutical formulations seems very attractive. Results obtained in this study give a comprehensive insight into the release mechanism of phloridzin acetates from emulsions and liposomes, enable the selection of optimum cosmetic formulations depending on the application, and provide significant scientific contribution in the field of topical administration of bioactive flavonoid derivatives.

Formulation of lyotropic liquid crystal emulsion based on natural sucrose ester and its tribological behavior as novel lubricant

The tribological behavior of oil-in-water emulsions formulated with natural lyotropic liquid crystal (LLC) emulsifiers based on natural sucrose ester was studied for the first time. Polarized optical microscopy, synchrotron radiation small-angle X-ray scattering, wide-angle X-ray scattering, and synchrotron radiation infrared microspectroscopy demonstrated that LLC emulsifiers were tightly ordered at the oil—water interface with a distinct nematic texture. The viscosity of emulsion was observed to change over time. Moreover, the zeta potential and laser particle size distribution verified the emulsion’s satisfactory stability. The frictional shearing test proved that the coefficient of friction of the emulsion versus pure oil decreased by 34.2%. The coefficient of friction of the emulsion with liquid crystal decreased 10.1% versus that without liquid crystal. Although liquid crystal emulsion did not exhibit outstanding anti-wear performance compared with pure oil, its wear volume was 29.4% less than the emulsion without liquid crystal. X-ray photoelectron spectroscopy and scanning electron microscope—energy dispersive X-ray spectroscopy (SEM—EDS) proved that the tribo-film of the emulsion with liquid crystal was formed synergistically by the liquid crystal phase with the base oil. The formulation affecting the lubricant quality was further studied by orthogonal experiments. The resulting Stribeck curve behavior suggested that proper composition with a slightly higher viscosity can better reduce friction in both boundary lubrication and mixed lubrication regimes. The lubrication mechanism indicated that the periodically ordered liquid crystal was transported to the sliding asperity in the form of emulsion droplets, which bored the pressure and released the oil to form a tribo-film. This LLC emulsion is environmentally friendly and potentially non-irritant to the skin. Thus, it has promising application prospects as novel water-based and biological lubricants.