Acoustic field visualisation using local absorption of ultrasound and thermochromic liquid crystals

Acoustic field and vibration visualisation is important in a wide range of applications. Laser vibrometry is often used for such visualisation, however, the equipment has a high cost and requires significant user expertise, and the method can be slow, as it requires scanning point by point. Here we suggest a different approach to visualisation of acoustic fields in the kHz - MHz range, using paint-on or removable film sensors, which produce a direct visual map of ultrasound displacement. The sensors are based on a film containing thermochromic liquid crystals (TLC), along with a backing/underlay layer which improves absorption of ultrasound. The absorption generates heat, which can be seen by a change in colour of the TLC film. A removable sensor is used to visualise the resonant modes of an air-coupled flexural transducer operated from 410 kHz to 7.23 MHz, and to visualise 40 kHz standing waves in a Perspex plate. The thermal basis of the visualisation is confirmed using thermal imaging. The speed and cost of visualisation makes the new sensor attractive for use in condition monitoring, for fast assessment of transducer quality, or for analysis of acoustic field distribution in power ultrasonic systems.

Supertwisted Chiral Gyroid Mesophase in Chiral Rod-Like Compounds

Among the intriguing bicontinuous self-assembled structures, the gyroid cubic is the most ubiquitous. It is found in block and star polymers, surfactants with or without solvent, in thermotropic liquid crystals with end- or side-chains, and in biosystems providing structural color and modelling cell mitosis. It contains two interpenetrating networks of opposite chirality and is thus achiral if, as usual, the content of the two nets is the same. However, we now find that this is not the case for strongly chiral compounds. While achiral molecules follow the opposite twists of nets 1 and 2, molecules with a chiral center in their rod-like core fail to follow the 70° twist between junctions in net 2 and instead wind against it by -110° to still match the junction orientation. The metastable chiral gyroid is a high-entropy high-heat-capacity mesophase. The homochirality of its nets makes the CD signal of the thienofluorenone compounds close to that in the stable I23 phase with 3 isochiral nets.

Investigation of solute-solvent interactions of 4'-alkyl-4-cyanobiphenyl liquid crystals using Raman spectroscopy

Liquid crystal materials possess hybrid liquid and solid-like properties with high response to stimuli. The 4'-alkyl-4-cyanobiphenyls (nCB) are an important class of liquid crystals that are widely used for various applications. In this study, six alkylcyanobiphenyl liquid crystal samples (5CB to 10CB) were examined using Raman spectroscopy in a total of twelve solvents of various polarities. The distinctive bands contributed by the LC sample are from C≡N stretch, C-C aromatic ring breathing, C-C biphenyl linking stretch, and C-H in-plane deformation. These modes are found to be responsive to different solvent environments by shifting positions. For instance, the cyano stretching mode of 5CB is blue-shifted from 2229 cm-1 for the pure sample to 2233 cm-1 when measured in hexane due to the repulsive interaction between the mode and the solvent bath. On the other hand, this mode undergoes a red-shift to 2220 cm-1 in methanol due to hydrogen bond interaction between the mode and solvent molecules. Overall, the shift in the position of the vibrational modes of nCB molecules was correlated with solvent properties such as acceptor number, donor number, and Kamlet-Taft dipolarity constants, which are a measure of solvent polarity. In samples with longer alkyl chains (8CB, 9CB, and 10CB), the wavenumber of the stretching modes was generally shifted to around the same position in all the solvents. Such observations are related to the folding back effect and enhanced dimerization constant with an increase in the chain length.

Targeted delivery of genistein for pancreatic cancer treatment using hyaluronic-coated cubosomes bioactivated with frankincense oil

Pancreatic cancer is an aggressive malignancy that remains a major cause of cancer-related deaths. Research for innovative anticancer therapeutic options is thus imperative. In this regard, phytotherapeutics offer great promise as efficient treatment modalities, especially leveraging nanodrug delivery. Herein, we innovatively coloaded the flavonoid genistein (Gen) and frankincense essential oil (FO) within cubosomes, which were then coated with the bioactive ligand hyaluronic acid (HA/Gen-FO-Cub) for active-targeting of pancreatic cancer. The novel HA/Gen-FO-Cub displayed optimum nanosize (198.2 ± 4.5 nm), PDI (0.27 ± 0.01), zeta-potential (-34.7 ± 1.2 mV), Gen entrapment (99.3 ± 0.01 %), and controlled Gen release (43.7 ± 1.2 % after 120 h). HA/Gen-FO-Cub exerted selective anticancer activity on pancreatic cancer cells (PANC-1; 8-fold drop in IC50), cellular uptake and anti-migratory effect compared to Gen solution. HA/Gen-FO-Cub revealed prominent cytocompatibility (100 ± 5.9 % viability of human dermal fibroblast). Moreover, HA/Gen-FO-Cub boosted the in vivo anticancer activity of Gen in an orthotopic cancer model, affording tumor growth suppression (2.5-fold drop) and downregulation of NFκB and VEGF (2.9- and 1.8-fold decrease, respectively), compared to Gen suspension. Antimetastatic efficacy and Bcl-2-downexpression was histologically confirmed. Our findings demonstrate the promising anticancer aptitude of HA/Gen-FO-Cub as an effective phytotherapeutic nanodelivery system for pancreatic cancer therapy.

Polarisation and rheology characterisation of monoolein/water liquid crystal dynamical behaviour during high-viscosity injector extrusion

HYPOTHESIS

The use of monoolein/water mixtures in serial crystallography experiments using high-viscosity injectors (HVI) results in significant departures from equilibrium behaviour. This is expected to include changes in phase, viscosity, and associated flow behaviour. It should be possible to detect these changes, in-situ, using a combination of polarisation and rheology characterisation techniques.

EXPERIMENTS

A systematic study was performed using monoolein, varying the water content to create a range of mixtures. Injection induced phase changes within the HVI flow were established using real-time cross-polarization measurements. Dynamic flow characteristics and viscosity was characterized by particle tracking and rheology.

FINDINGS

HVI injection induces deformation and phase changes within monoolein (MO)/water mixtures which can be detected through variations in the transmitted intensity during in-situ polarisation studies. The heterogeneity of the extruded sample results in a highly viscous cubic phase in the central region of the stream and a less viscous lamellar-rich phase at the edges adjacent to the walls. The extent of these variations depends on sample composition and injection conditions. Shear-thinning behaviour and increasing heterogeneity in the vicinity of the capillary walls under dynamic flow conditions. This is the first report observing injection induced dynamical behaviour in MO/water mixtures under realistic flow conditions.

Lyotropic liquid crystalline phases: Drug delivery and biomedical applications

Liquid crystal (LC)-based nanoformulations may efficiently deliver drugs and therapeutics to targeted biological sites. Lyotropic liquid crystalline phases (LLCPs) have received much interest in recent years due to their unique structural characteristics of both isotropic liquids and crystalline solids. These LLCPs can be utilized as promising drug delivery systems to deliver drugs, proteins, peptides and vaccines because of their improved drug loading, stabilization, and controlled drug release. The effects of molecule shape, microsegregation, and chirality are very important in the formation of liquid crystalline phases (LCPs). Homogenization of self-assembled amphiphilic lipids, water and stabilizers produces LLCPs with different types of mesophases, bicontinuous cubic (cubosomes) and inverse hexagonal (hexosomes). Moreover, many studies have also shown higher bioadhesivity and biocompatibility of LCs due to their structural resemblance to biological membranes, thus making them more efficient for targeted drug delivery. In this review, an outline of the engineering aspects of LLCPs and polymer-based LLCPs is summarized. Moreover, it covers parenteral, oral, transdermal delivery and medical imaging of LC in targeting various tissues and is discussed with a scope to design more efficient next-generation novel nanosystems. In addition, a detailed overview of advanced liquid crystal-based drug delivery for vaccines and biomedical applications is reviewed.

Controlling the nanocellulose morphology by preparation conditions

Nanocellulose (NC) is the desired building block for novel biomaterials. The morphology of NC is one of the core parameters impacting the functionality and property of engineered functional materials. This work aims to reveal the relationship between the product morphology and sulfuric acid hydrolysis conditions (including acid concentration, temperature and time), and to realize morphological regulation of obtained NC. Three representative products were obtained from microcrystalline cellulose via sulfuric acid hydrolysis, which are cellulose nanocrystals with broad size distribution (W-CNC, 383.9 ± 131.7 nm in length, 6 ± 2.1 nm in height) obtained by 61 % H2SO4, 55 °C and 90 min, cellulose nanospheres (CNS, 61.3 ± 15.9 nm in diameter) obtained by 64 % H2SO4, 35 °C and 75 min, and CNC with narrow size distribution (N-CNC, 276.1 ± 28.7 nm in length, 4.1 ± 0.6 nm in height), obtained by 64 % H2SO4, 45 °C and 45 min. The results showed that the crystallographic form of W-CNC and N-CNC are cellulose I, while cellulose I and II coexist in CNS. Only W-CNC and N-CNC can form chiral nematic structures through evaporation-induced self-assembly strategy and reflected light with specific wavelengths. In addition, the formation mechanism of CNS with cellulose I/II was proposed, which provided a better understanding of NC morphology regulation.

The Influence of Positional Isomerism of Terminal Alkyl Chains on Mesomorphic and Photophysical Behavior of Unsymmetric α-cyanostilbene-based Tetracatenars

Two series of unsymmetric α-cyanostilbene-based tetracatenars containing three hexadecyl chains at one end and one alkyl chain with varying lengths at the other end were prepared by using Suzuki coupling and Knoevenagel reactions. These tetracatenars with the terminal three hexadecyl chains, which are adjacent to the cyano group are non-mesogens, whereas the isomers with one alkyl chain, which is adjacent to the cyano group display transition from non-mesogens to monotropic hexagonal columnar liquid crystal upon elongation of the alkyl chain. This transition could be attributed to that the three hexadecyl chains which are adjacent to the cyano group decrease the interactions between π-conjugated rigid cores, hindering the formation of mesophase. In addition, weak slovatochromism implies weak ICT in both series tetracatenars. Both series isomers exhibit distinct AIE characteristics attributing to the presence of α-cyanostilbene, which could induce stereoisomerism and restricted intermolecular rotation in the aggregated state. Different mechanochromism behaviors could be achieved due to the positional isomerism of terminal alkyl chains. Therefore, tuning the position of terminal alkyl chains could give rise to distinct changes in the molecular aggregate, which provides a scheme to build multifunctional materials with diverse potentials.

Diverse Synthetic Transformations Using 4-Bromo-3,3,4,4-tetrafluorobut-1-ene and Its Applications in the Preparation of CF2 CF2 -Containing Sugars, Liquid Crystals, and Light-Emitting Materials

Organic molecules with fluoroalkylene scaffolds, especially a tetrafluoroethylene (CF2 CF2 ) moiety, in their molecular structures exhibit unique biological activities, or can be applied to functional materials such as liquid crystals and light-emitting materials. Although several methods for the syntheses of CF2 CF2 -containing organic molecules have been reported to date, they have been limited to methods using explosives and fluorinating agents. Therefore, there is an urgent need to develop simple and efficient approaches to synthesize CF2 CF2 -containing organic molecules from readily available fluorinated substrates using carbon-carbon bond formation reactions. This personal account summarizes the simple and efficient transformation of functional groups at both ends of 4-bromo-3,3,4,4-tetrafluorobut-1-ene and discusses its synthetic applications to biologically active fluorinated sugars and functional materials, such as liquid crystals and light-emitting molecules.

Development of Donor-π-Acceptor-Type Fluorinated Tolanes as Compact Condensed Phase Luminophores and Applications in Photoluminescent Liquid-Crystalline Molecules

Fluorinated tolanes, produced by introducing fluorine atoms into one of the aromatic rings of tolane, emitted almost no fluorescence in a solution state, but the fluorescence intensity increased dramatically in the crystalline state because of intermolecular H⋅⋅⋅F hydrogen bonds. The photoluminescent (PL) colors depend on the molecular orbitals, dipole moments, and molecular aggregated structures can be varied by controlling terminal substituents along the major molecular axis. The introduction of a long alkoxy or semifluoroalkoxy unit as a flexible chain into the terminal positions along the major molecular axis induced the formation of a liquid-crystalline (LC) phase; fluorinated tolanes act both as luminophores and as mesogens, leading to the molecular design of new photoluminescent LC molecules (PLLCs). The results also indicated that a fluorinated tolane dimer, which consists of two fluorinated tolanes linked by a flexible alkylene spacer, also becomes a novel PLLC.

F3 peptide functionalized liquid crystalline nanoparticles for delivering Salinomycin against breast cancer

Salinomycin (Sal) is a potent veterinary antibiotic known to offer significant toxicity to the variety of neoplastic cells. Its therapeutic utility is limited due to its higher lipophilicity (logP 7.5) and poor hydrophilicity. Liquid crystalline nanoparticles (LCNPs) known to offer a suitable delivery platform for these kinds of drugs. The overexpressed nucleolin receptor on the cell surface and cytoplasm, could be selected as a target in cancer therapy. The present study involves the development and characterization of the F3 peptide functionalized LCNPs for delivering Sal (F3-Sal-NPs) for selectively targeting to the nucleolin receptor. The optimized LCNPs were characterized for particle size, zeta potential, surface morphology, drug release kinetics and stability. The LCNPs have a structure similar to nematic phases. In vitro drug release studies revealed sustained drug release characteristics (89.5 ± 1.5% at 120 h) with F3-Sal-NPs. The cytotoxicity results demonstrated that F3-Sal-NPs were 4.8, 2.6 and 5.5 folds more effective than naïve drug in MDA-MB-468, MDA-MB-231 and MCF-7 cells, respectively and the cell cycle was arrested in the S and G2/M phases. The expression of the gene responsible for the stemness (CD44 gene), apoptosis (BAX/Bcl-2 ration) and angiogenesis (LCN-2) was reduced by F3-Sal-NPs treatment. Ex vivo hemolytic toxicity was reduced (6.5 ± 1.5%) and the pharmacokinetics and bioavailability of Sal was improved with F3-Sal-NPs. The in vivo antitumor efficacy was tested in EAC bearing mice, where F3-Sal-NPs significantly reduced the tumor growth by 2.8-fold compared to pure Sal and induced necrosis of tumor cells. The results clearly demonstrate the outstanding performance of F3 peptide functionalized LCNPs for delivering Sal against breast cancer.

Liquid-crystalline assembly of spherical cellulose nanocrystals

Rod-shaped cellulose nanocrystals (CNCs), also called cellulose nanorods (CNRs), possess anisotropic properties that allow for their self-organization into chiral nematic liquid crystals. Interestingly, spherical cellulose nanocrystals (cellulose nanospheres, CNSs) have also been shown to form a chiral liquid-crystalline phase in recent years. Herein, to understand how the similar assembly takes places as particle dimension changes, the organization features of CNSs were investigated. Results of this study demonstrate that above a critical concentration in suspension, CNSs organize into a liquid-crystal phase consisting of periodically parallel-aligned layer structures. This structure persists after suspension drying. In comparison with CNRs, the alignment of CNSs exhibits a shorter layer distance, lower order degree, and weaker long-range orientation. To explain the early stages of tactoid formation, a "caterpillar-like" model was proposed, which was captured by freezing the CNS suspension in an intermediate aggregation state. This structure serves as the fundamental unit for further liquid-crystal assembly.

Exploring temozolomide encapsulated PEGylated liposomes and lyotropic liquid crystals for effective treatment of glioblastoma: in-vitro, cell line, and pharmacokinetic studies

Temozolomide (TMZ) is one of the best choices for treating glioblastoma. However, due to the short plasma half-life, only 20-30 % brain bioavailability can be achieved using traditional formulations. In the present study, PEGylated liposomes and lyotropic liquid crystals (LLCs) were developed and investigated to prolong the plasma circulation time of TMZ. Industrially feasible membrane extrusion and modified hot melt emulsification techniques were utilized during the formulation. Liposomes and LLCs in the particle size range of 80-120 nm were obtained with up to 50 % entrapment efficiency. The nanocarriers were found to show a prolonged release of up to 72 h. The cytotoxicity studies in glioblastoma cell lines revealed a ∼1.6-fold increased cytotoxicity compared to free TMZ. PEGylated liposomes and PEGylated LLCs were found to show a 3.47 and 3.18-fold less cell uptake in macrophage cell lines than uncoated liposomes and LLCs, respectively. A 1.25 and 2-fold increase in the plasma t1/2 was observed with PEGylated liposomes and PEGylated LLCs, respectively, compared to the TMZ when administered intravenously. Extending plasma circulation time of TMZ led to significant increase in brain bioavailability. Overall, the observed improved pharmacokinetics and biodistribution of TMZ revealed the potential of these PEGylated nanocarriers in the efficient treatment of glioblastoma.

Non-equilibrium ordering of liquid crystalline (LC) films driven by external gradients in surfactant concentration

HYPOTHESIS

Gradients in the concentration of amphiphiles play an important role in many non-equilibrium processes involving complex fluids. Here we explore if non-equilibrium interfacial behaviors of thermotropic (oily) liquid crystals (LCs) can amplify microscopic gradients in surfactant concentration into macroscopic optical signals.

EXPERIMENTS

We use a milli-fluidic system to generate gradients in aqueous sodium dodecyl sulfate (SDS) concentration and optically quantify the dynamic ordering of micrometer-thick nematic LC films that contact the gradients.

FINDINGS

We find that the reordering of the LCs is dominated by interfacial shearing by Marangoni flows, thus providing simple methods for rapid mapping of interfacial velocities from a single optical image and investigating the effects of confinement of surfactant-driven interfacial flows. Additionally, we establish that surface advection and surfactant desorption are the two key processes that regulate the interfacial flows, revealing that the dynamic response of the LC can provide rapid and potentially high throughput approaches to measurement of non-equilibrium interfacial properties of amphiphiles. We also observe flow-induced assemblies of microparticles to form at the LC interface, hinting at new non-equilibrium approaches to microparticle assembly. We conclude that dynamic states adopted by LCs in the presence of surfactant concentration gradients provide new opportunities for engineering complex fluids beyond equilibrium.

Controlling liquid crystal boojum defects on fixed microparticle arrays via capillarity-assisted particles assembly

HYPOTHESIS

Colloidal particles in nematic liquid crystals (LCs) are of high interest for self-assembly of soft matter systems. When two free particles approach within a uniaxially-oriented nematic LC, an elastic force is generated due to the distorted nematic director configuration around them, allowing particles to self-assemble by an attractive force. We hypothesize that if particles are immobilized, repulsive forces emerge instead, causing the deflection of the interacting defects to compensate for the energy increase.

EXPERIMENTS

We fabricated tailored arrays of spherical silica microparticles via capillarity-assisted particle assembly (CAPA) to investigate the interactions of defects as a function of particle separation. By transferring the particle arrays from the CAPA templates to a glass substrate, we studied interacting boojum defect textures within thin LC films sandwiched between two substrates using polarized optical microscopy (POM).

FINDINGS

We observed deflected boojum defects on arrays of fixed silica particles, confirming our hypothesis that the elastic repulsive force between the particles affects the defect orientation. The nematic director configuration is reconstructed by Landau-de Gennes q-tensor modeling, and simulated POM images are obtained by the Jones-Matrix method. Our results provide a new platform for controlling defect interactions and pave the way for future work to study topology and implement new defect based applications in LC films.

Effects of Biliary Phospholipids on Cholesterol Crystallization and Growth in Gallstone Formation

The prevalence of cholesterol gallstone disease is increasing, primarily due to the global epidemic of obesity associated with insulin resistance, and this trend leads to a considerable healthcare, financial, and social burden worldwide. Although phospholipids play an essential role in maintaining cholesterol solubility in bile through both mixed micelles and vesicles, little attention has been paid to the impact of biliary phospholipids on the pathogenesis of cholesterol gallstone formation. A reduction or deficiency of biliary phospholipids results in a distinctly abnormal metastable physical-chemical state of bile predisposing to supersaturation with cholesterol. Changes in biliary phospholipid concentrations influence cholesterol crystallization by yielding both liquid crystalline and "anhydrous" crystalline metastable intermediates, evolving into classical parallelogram-shaped cholesterol monohydrate crystals in supersaturated bile. As a result, five distinct crystallization pathways, A-E, have been defined, mainly based on the prime habits of liquid and solid crystals in the physiological or pathophysiological cholesterol saturation of gallbladder and hepatic bile. This review concisely summarizes the chemical structures and physical-chemical properties of biliary phospholipids and their physiological functions in bile formation and cholesterol solubility in bile, as well as comprehensively discusses the latest advances in the role of biliary phospholipids in cholesterol crystallization and growth in gallstone formation, largely based on the findings from clinical and animal studies and in vitro experiments. The insights gleaned from uncovering the cholelithogenic mechanisms are expected to form a fundamental framework for investigating the hitherto elusive events in the earliest stage of cholesterol nucleation and crystallization. This may help to identify better measures for early diagnosis and prevention in susceptible subjects and effective treatment of patients with gallstones.

Liquid crystal based active electrocaloric regenerator

The active electrocaloric (EC) regenerator exploiting electric conversion into thermal energy has recently become important for developing a new generation of heat-management devices. We analyze an active EC regenerator numerically. We establish a temperature span across the regenerator Δ T by commuting a liquid crystalline (LC) unit between regions with and without an external electric field E. In modelling, we use Landau-de Gennes mesoscopic approach, focusing on the temperature regime where isotropic (paranematic) and nematic phase order compete. We determined conditions enabling a large enough value of Δ T suitable for potential applications. In particular, (i) the vicinity of the paranematic-nematic (P-N) phase transition, (ii) large enough latent heat of the transition, (iii) strong enough applied external field (exceeding the critical field E _c at which the P-N transition becomes gradual), and (iv) relatively short contact times between LC unit and heat sink and heat source reservoirs are advantageous. Our analysis reveals that Δ T ≫ 1 K could be achieved using appropriate LC material.

Lipidic lyotropic liquid crystals: Insights on biomedical applications

Liquid crystals (LCs) possess unique physicochemical properties, translatable into a wide range of applications. To date, lipidic lyotropic LCs (LLCs) have been extensively explored in drug delivery and imaging owing to the capability to encapsulate and release payloads with different characteristics. The current landscape of lipidic LLCs in biomedical applications is provided in this review. Initially, the main properties, types, methods of fabrication and applications of LCs are showcased. Then, a comprehensive discussion of the main biomedical applications of lipidic LLCs accordingly to the application (drug and biomacromolecule delivery, tissue engineering and molecular imaging) and route of administration is examined. Further discussion of the main limitations and perspectives of lipidic LLCs in biomedical applications are also provided. STATEMENT OF SIGNIFICANCE: Liquid crystals (LCs) are those systems between a solid and liquid state that possess unique morphological and physicochemical properties, translatable into a wide range of biomedical applications. A short description of the properties of LCs, their types and manufacturing procedures is given to serve as a background to the topic. Then, the latest and most innovative research in the field of biomedicine is examined, specifically the areas of drug and biomacromolecule delivery, tissue engineering and molecular imaging. Finally, prospects of LCs in biomedicine are discussed to show future trends and perspectives that might be utilized. This article is an ampliation, improvement and actualization of our previous short forum article "Bringing lipidic lyotropic liquid crystal technology into biomedicine" published in TIPS.

Liquid crystal phase formation and non-Newtonian behavior of oligonucleotide formulations

Viscosity behavior of liquid oligonucleotide therapeutics and its dependence on formulation properties has been poorly studied to date. We observed a high increase in viscosity and solidification of therapeutic oligonucleotide formulations with increasing oligonucleotide concentration creating challenges during drug product manufacturing. In this study, we characterized the viscosity behavior of three different single strand DNA oligonucleotides based on oligonucleotide concentration and formulation composition. We subsequently studied the underlying mechanism for increased viscosity at higher oligonucleotide concentrations by dynamic light scattering (DLS), 1H nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and polarized light microscopy. Viscosity was highly dependent on formulation composition, oligonucleotide sequence, and concentration, and especially dependent on the presence and combination of different individual ions, such as the presence of sodium chloride in the formulation. In samples with elevated viscosity, the viscosity behavior was characterized by non-Newtonian, shear-thinning flow behavior. We further studied these samples by DLS and 1H NMR, which revealed the presence of supra-molecular assemblies, and further characterization by polarized light and DSC characterized these assemblies as liquid crystals in the formulation. The present study links the macroscopic viscosity behavior of oligonucleotide formulations to the formation of supra-molecular assemblies and to the presence of liquid crystals, and highlights the importance of formulation composition selection for these therapeutics.

Rapid, label-free and low-cost diagnostic kit for COVID-19 based on liquid crystals and machine learning

We report a label-free method for detection of the SARS-CoV-2 virus in nasopharyngeal swab samples without purification steps and multiplication of the target which simplifies and expedites the analysis process. The kit consists of a textile grid on which liquid crystals (LC) are deposited and the grid is placed in a crossed polarized microscopy. The swab samples are subsequently placed on the LCs. In the presence of a particular biomolecule, the direction of LCs changes locally based on the properties of the biomolecule and forms a particular pattern. As the swab samples are not perfectly purified, image processing and machine learning techniques are employed to detect the presence of specific molecules or quantify their concentrations in the medium. The method can differentiate negative and positive COVID-19 samples with an accuracy of 96% and also differentiate COVID-19 from influenza types A and B with an accuracy of 93%. The kit is portable, simple to manufacture, convenient to operate, cost effective, rapid and sensitive. The simplicity of the specimen processing, the speed of image acquisition, and fast diagnostic operations enable the deployment of the proposed technique for performing extensive on-spot screening of COVID-19 in public places.

Interactions of a biological macromolecule with thermotropic liquid crystals: Applications of liquid crystals in biosensing platform

Liquid crystal biosensor was developed based on a 4'-octyl-4-biphenylcarbonitrile (8CB) by adsorption of biological macromolecule bovine serum albumin (BSA) at the 8CB interface. BSA was detected by examining the changes in the director configurations of 8CB molecules under a polarizing optical microscope. The transitions in the director configuration were due to the non-covalent bonds. This technique demonstrated high sensitivity at a concentration of 100 µM of BSA. The binding events between the 8CB and BSA were investigated through molecular docking studies that confirmed the protein-ligand interaction. The most probable binding location of 8CB to dock with BSA were determined at a subdomain IB of Sudlow's site I. The active residues on analyzing were found to stabilize the 8CB molecules through different interactions. These active residues that were involved in the protein-ligand interaction were further confirmed with Raman spectroscopy. This study provided the vibrational properties and structural changes that occurred due to the various interactions between the 8CB and BSA. The results presented in this work lead to a potential biosensing tool for detecting and sensing proteins using LCs.

Monodomain Liquid Crystals of Two-Dimensional Sheets by Boundary-Free Sheargraphy

Eliminating topological defects to achieve monodomain liquid crystals is highly significant for the fundamental studies of soft matter and building long-range ordered materials. However, liquid crystals are metastable and sensitive to external stimuli, such as flow, confinement, and electromagnetic fields, which cause their intrinsic polycrystallinity and topological defects. Here, we achieve the monodomain liquid crystals of graphene oxide over 30 cm through boundary-free sheargraphy. The obtained monodomain liquid crystals exhibit large-area uniform alignment of sheets, which has the same optical polarized angle and intensity. The monodomain liquid crystals provide bidirectionally ordered skeletons, which can be applied as lightweight thermal management materials with bidirectionally high thermal and electrical conductivity. Furthermore, we extend the controllable topology of two-dimensional colloids by introducing singularities and disclinations in monodomain liquid crystals. Topological structures with defect strength from - 2 to + 2 were realized. This work provides a facile methodology to study the structural order of soft matter at a macroscopic level, facilitating the fabrication of metamaterials with tunable and highly anisotropic architectures.

Advanced cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF) aerogels: Bottom-up assembly perspective for production of adsorbents

The most common and abundant polymer in nature is the linear polysaccharide cellulose, but processing it requires a new approach since cellulose degrades before melting and does not dissolve in ordinary organic solvents. Cellulose aerogels are exceptionally porous (>90 %), have a high specific surface area, and have low bulk density (0.0085 mg/cm³), making them suitable for a variety of sophisticated applications including but not limited to adsorbents. The production of materials with different qualities from the nanocellulose based aerogels is possible thanks to the ease with which other chemicals may be included into the structure of nanocellulose based aerogels; despite processing challenges, cellulose can nevertheless be formed into useful, value-added products using a variety of traditional and cutting-edge techniques. To improve the adsorption of these aerogels, rheology, 3-D printing, surface modification, employment of metal organic frameworks, freezing temperature, and freeze casting techniques were all investigated and included. In addition to exploring venues for creation of aerogels, their integration with CNC liquid crystal formation were also explored and examined to pursue "smart adsorbent aerogels". The objective of this endeavour is to provide a concise and in-depth evaluation of recent findings about the conception and understanding of nanocellulose aerogel employing a variety of technologies and examination of intricacies involved in enhancing adsorption properties of these aerogels.

A systemic review on liquid crystals, nanoformulations and its application for detection and treatment of SARS - CoV- 2 (COVID - 19)

The COVID-19 is a pandemic caused by the SARS-CoV-2 virus, has instigated major health problems and prompted WHO to proclaim a worldwide medical emergency. The knowledge of SARS-CoV-2 fundamental structure, aetiology, its entrance mechanism, membrane hijacking and immune response against the virus, are important parameters to develop effective vaccines and medicines. Liquid crystals integrated nano-techniques and various nanoformulations were applied to tackle the severity of the virus. It was reported that nanoformulations have helped to enhance the effectiveness of presently accessible antiviral medicines or to elicit a fast immunological response against COVID-19 virus. Applications of liquid crystals, nanostructures, nanoformulations and nanotechnology in diagnosis, prevention, treatment and tailored vaccine administration against COVID-19 which will help in establishing the framework for a successful pandemic combat are reviewed. This review also focuses on limitations associated with liquid crystal-nanotechnology based systems and suggests the possible ways to address these limitations. Also, topical advancements in the ground of liquid crystals and nanostructures established diagnostics (nanosensor/biosensor) are discussed in detail.

Ordered porous and uniform electric-field-strength micro-supercapacitors by 3D printing based on liquid-crystal V2O5 nanowires compositing carbon nanomaterials

The design of electrode internal structure plays an important role in improving the performance of micro-supercapacitors (MSCs). However, the complexity of the program hinders the development and application of Three-dimensional(3D)-printed MSCs. Herein, printable inks were prepared by using vanadium pentoxide nanowires as active materials, carbon nanotubes as collector and conductive agent, graphene oxide as adhesive, scaffold and water retaining agent. Benefiting from the liquid-crystal properties of materials and 3D printing technology as well as the adjustment of the materials proportion, onion-like structures with ordered porous layered structure and uniform electric-field-strength MSCs were constructed. The 3D-printed MSC has fine area capacitance (34.68 mF cm^-2) and area energy density (1.73 µWh cm^-2 at a current density of 0.24 mA cm^-2). Therefore, using the unique characteristics of materials to build an efficient 3D printing strategy is expected to provide a feasible solution for the construction of various MSCs and other high-energy storage systems.

Lyotropic liquid crystals for parenteral drug delivery

The necessity for long-term treatments of chronic diseases has encouraged the development of novel long-acting parenteral formulations intending to improve drug pharmacokinetics and therapeutic efficacy. Lately, one of the novel approaches has been developed based on lipid-based liquid crystals. The lyotropic liquid crystal (LLC) systems consist of amphiphilic molecules and are formed in presence of solvents with the most common types being cubic, hexagonal and lamellar mesophases. LC injectables have been recently developed based on polar lipids that spontaneously form liquid crystal nanoparticles in aqueous tissue environments to create the in-situ long-acting sustained-release depot to provide treatment efficacy over extended periods. In this manuscript, we have consolidated and summarized the various type of liquid crystals, recent formulation advancements, analytical evaluation, and therapeutic application of lyotropic liquid crystals in the field of parenteral sustained release drug delivery.

The stochastic organization of genomes and the doctrine of energy-information evolution based on bio-antenna arrays

The article is devoted to the possibilities of considering the evolution of biological systems in connection with the unique emergent properties of antenna arrays, that is, systems of mutually matched antennas widely used in technology. Materials are presented in favor of the proposition that the evolution of biosystems can be formally considered as the evolution of systems of bio-antenna arrays and their energy-information wave activity, which participates in biological computation and contributes to the unification of body parts into a coherent whole. The use of digital antenna arrays in technology is based on their tensor-matrix theory. The author discovers a structural analogy of this theory with the tensor-matrix features of genetic coding systems, as well as algebraic modeling of the universal rules for the stochastic DNA organization of the genomes of higher and lower organisms. This analogy is just one of the facts presented in the article in favor of the usefulness of borrowing knowledge from modern antenna technology to consider the evolution of biosystems. The described new approach may exist along with other known approaches in evolutionary biology.

Assembling Microtubule-Based Active Matter

Studied for more than a century, equilibrium liquid crystals provided insight into the properties of ordered materials, and led to commonplace applications such as display technology. Active nematics are a new class of liquid crystal materials that are driven out of equilibrium by continuous motion of the constituent anisotropic units. A versatile experimental realization of active nematic liquid crystals is based on rod-like cytoskeletal filaments that are driven out of equilibrium by molecular motors. We describe protocols for assembling microtubule-kinesin based active nematic liquid crystals and associated isotropic fluids. We describe the purification of each protein and the assembly process of a two-dimensional active nematic on a water-oil interface. Finally, we show examples of nematic formation and describe methods for quantifying their non-equilibrium dynamics.

Stability, flow alignment and a phase transition of the lipidic cubic phase during continuous flow injection

Continuous flow injection is a key technology for serial crystallography measurements of protein crystals suspended in the lipidic cubic phase (LCP). To date, there has been little discussion in the literature regarding the impact of the injection process itself on the structure of the lipidic phase. This is despite the fact that the phase of the injection matrix is critical for the flow properties of the stream and potentially for sample stability. Here we report small-angle X-ray scattering measurements of a monoolein:water mixture during continuous delivery using a high viscosity injector. We observe both an alignment and modification of the LCP as a direct result of the injection process. The orientation of the cubic lattice with respect to the beam was estimated based on the anisotropy of the diffraction pattern and does not correspond to a single low order zone axis. The solvent fraction was also observed to impact the stability of the cubic phase during injection. In addition, depending on the distance traveled by the lipid after exiting the needle, the phase is observed to transition from a pure diamond phase (Pn3m) to a mixture containing both gyriod (Ia3d) and lamellar (L_α) phases. Finite element modelling of the observed phase behaviour during injection indicates that the pressure exerted on the lipid stream during extrusion accounts for the variations in the phase composition of the monoolein:water mixture.

Nanoparticle adsorption induced configurations of nematic liquid crystal droplets

Nematic liquid crystal (LC) droplets have been widely used for the detection of molecular species. We investigate the response of micrometer sized nematic LC droplets against the adsorption of nanoparticles from aqueous media. We synthesized ∼ 100 nm-in-diameter silica nanoparticles and modified their surfaces to mediate either planar or homeotropic LC anchoring and a pH-dependent charge. We show surface functionality- and concentration-dependent configurations of the droplets consistent with the change in the surface anchoring and the formation of local heterogeneities upon adsorption of the nanoparticles to LC-aqueous interfaces. The adsorption of nanoparticles modified with dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (DMOAP, homeotropic) exhibit a transition from bipolar to radial, whereas the adsorption of -COOH-terminated counterparts (planar) did not cause a configuration transition. By manipulating the electrostatic interactions, we controlled the adsorption of the nanoparticles to the LC-aqueous interfaces, providing access to the physicochemical properties of the nanoparticles. We demonstrate a temporal change in the droplet configurations caused by the adsorption of the nanoparticles functionalized with -COOH/DMOAP mixed monolayers. These results provide a basis for studies in applications for the detection of nano-sized species, for sensing applications that combine nanoparticles with LCs, and for the synthesis of anisotropic composite particles with complex structures.

Metal-Organic Framework superstructures with long-ranged orientational order via E-field assisted liquid crystal assembly

Most MOFs are non-cubic, with functionality dependent upon crystallographic direction, and are largely prepared as microcrystalline powders. Therefore, general methods to orient and assemble free-standing MOF crystals are especially important and urgently needed. This is addressed here through the novel strategy of E-field assisted liquid crystal assembly, applied to MIL-53-NH₂(Al), MIL-68(In) and NU-1000 MOF crystals, with aspect ratios ranging from 10 to 1.2, to form highly oriented MOF superstructures which were photopolymerized to fix their long-ranged order. This new strategy for controlling MOF orientation and packing side-steps the traditional requirements of particle monodispersity, shape homogeneity and high aspect ratios (>4.7) typical of colloidal and liquid crystal assembly, and is applicable even to polydispersed MOF crystals, thereby paving the way towards the development of highly oriented MOF composites with improved functionality.

Methods for Small-Angle Scattering Measurements on Peptiplexes of DNA with Cell-Penetrating Peptides

Peptiplexes are soft biomaterials formed through the noncovalent association between cell-penetrating peptides and nucleic acids. Although internalization often involves electrostatic anchoring followed by endocytosis, the mode of action of these transporters remains elusive in many cases, and proper understanding of mechanisms behind their penetrating capabilities necessarily entails structural data at the nanoscopic scale. In this chapter, we examine the structural landscape of peptiplexes, emphasizing the complex behavior of these polyelectrolyte self-assemblies and how supramolecular order impacts their translocation efficiency. We discuss experimental tools commonly used to investigate the structure of peptiplexes and pay special attention to small-angle X-ray scattering (SAXS) as a suitable method for unveiling their nanoscale organization. A roadmap for standard SAXS measurements in CPP/DNA samples is presented alongside a selection of observations from our own experience dealing with SAXS applied to the investigation of CPPs.

Measurement of octanol-air partition coefficients for liquid crystals based on gas chromatography-retention time and its implication in predicting long-range transport potential

Liquid crystals (LCs) are widely used in the modern society, but their environmental fate and related human health effects remain inadequately recognized. To assist in better understanding the environmental fate of LCs, the octanol-air partition coefficients (K_OA) of 21 target LCs were determined with a gas chromatography-retention time (GC-RT) approach. Four classes of traditional organic pollutants, including polycyclic aromatic hydrocarbons, organochlorides, polybrominated diphenyl ethers, and polychlorinated biphenyls were employed as reference or calibration compounds. Cluster analysis indicated that the reference and calibration compounds somewhat influenced the relative and absolute magnitudes of GC-RT results. A quantitative structure-property relationship (QSPR) model was constructed from the experimental results and outperformed a widely-used model, KOAWIN, in estimating log K_OA of LCs. This model was used to predict log K_OAs for 116 LCs with the same element compositions and similar structures as the target LCs. Overall persistence and long-range transport potential were predicted based on the measured and estimated log K_OA values, yielding consistent results. Several LCs were shown to have comparable characteristic travel distances and transport efficiencies as the traditional organic pollutants, suggesting they are potential environmental pollutants and the QSPR model is applicable in predicting the environmental fate of LCs.

Synthesis and Liquid Crystalline Properties of Low Molecular Weight Bis-Chalcone Compounds

AIMS

In this paper, we report on the synthesis and liquid crystalline properties of some low molecular weight bis-chalcone compounds derived from acetone, cyclopentanone and cyclohexanone mesogenic cores.

BACKGROUND

Structurally bis-chalcones belong to a broader family of chalcone compounds. Chalcone is a compound that consists of two aromatic rings linked by an unsaturated α, β-ketone.

OBJECTIVE

Liquid crystalline chalcones are prepared by aliphatic chain substituents on two aromatic rings. Chalcones are well studied for their mesomorphic properties. Compared to a large number of chalcone based LCs reported, only a few articles have been published on the mesomorphic properties of bis-chalcone compounds. The target compounds of the present study varied not only in their central core but also in number and position of terminal aliphatic chain substitution-a key structural unit in deciding the liquid crystalline properties of a compound.

METHOD

All target compounds were synthesized in good yield by base catalyzed Claisen-Schmidt condensation reaction. Molecular structures were confirmed by FT-IR, 1H NMR, 13C NMR, and mass spectroscopic methods. Liquid crystalline property of these compounds was evaluated using polarizing optical microscopy and differential scanning calorimetry.

RESULTS

Although none of the acetone based compounds exhibited mesomorphism, cyclopentanone and cyclohexanone based compounds with octyloxy chain at para position on either side of the dibenzylidine ring stabilized liquid crystalline smectic (SmA and SmC) and nematic (N) phases. The observed structure-liquid crystalline property relationship was explained by structural analysis of molecules using DFT calculations. Considering the inherent photoluminescence nature of the chalcone moiety, a preliminary study was carried out on a selected compound to reveal its fluorescence property.

CONCLUSION

Our study brings about an important structure-liquid crystalline property relationship in a relatively unexplored class of bis-chalcone liquid crystals.

Recent advances on semiconducting nanomaterials-ferroelectric liquid crystals nanocomposites

Ferroelectric liquid crystals (FLCs) possess excellent electro-optical properties compared to nematic liquid crystals including lower threshold voltage, faster switching response, good optical contrast and bi-stable switching, memory effect, etc. Due to such characteristic features, FLCs are more promising for next generation high performance photonic applications. Moreover, the synergy of FLCs with nanoscience has clearly shown the enormous possibilities to improve upon their electro-optical properties. Over the past two decades, several investigations of nanomaterial (metal, metal oxide, ferroelectric, insulating, graphene, semiconducting etc.) dispersed FLC nanocomposites have been carried out. Semiconducting nanomaterials (SNMs), exhibiting quantum confinement effect, have been one of the most explored nanomaterials as dopants in FLCs leading to better molecular alignment, enhanced dielectric behavior, pronounced memory effect, power efficient, faster switching response and enhanced photoluminescence. Here, we present a focused review on SNMs-FLCs nanocomposites and propose future work to advance liquid crystal nanoscience.

Nanotechnology-based Drug Delivery Systems as Potential for Skin Application: A Review

Administration of substances through the skin represents a promising alternative, in relation to other drug administration routes, due to its large body surface area, in order to offer ideal and multiple sites for drug administration. In addition, the administration of drugs through the skin avoids the first-pass metabolism, allowing an increase in the bioavailability of drugs, as well as reducing their side effects. However, the stratum corneum (SC) comprises the main barrier of protection against external agents, mainly due to its structure, composition and physicochemical properties, becoming the main limitation for the administration of substances through the skin. In view of the above, pharmaceutical technology has allowed the development of multiple drug delivery systems (DDS), which include liquid crystals (LC), cubosomes, liposomes, polymeric nanoparticles (PNP), nanoemulsions (NE), as well as cyclodextrins (CD) and dendrimers (DND). It appears that the DDS circumvents the problems of drug absorption through the SC layer of the skin, ensuring the release of the drug, as well as optimizing the therapeutic effect locally. This review aims to highlight the DDS that include LC, cubosomes, lipid systems, PNP, as well as CD and DND, to optimize topical skin therapies.

Cellulose nanocrystals suspensions: Liquid crystal anisotropy, rheology and films iridescence

The properties of aqueous suspensions of cellulose nanocrystals (CNC) and their casted films are revised. The bio-nanoparticles are briefly introduced, including modifications of the crystals and the suspending media. The formation of CNC-derived liquid crystals (LC) and their resulting rheological behavior are presented. The effects of different variables are addressed: CNC aspect ratio, surface chemistry, concentration, time required for the appearance of an anisotropic phase and addition of other components to the suspension media. The changes on the structure induced by alignment, and by conditions of the drying process are also reported. The optical properties of the films are considered, and the effect of the above variables on the final transparency, iridescence and overall optical response of these bio-inspired photonic materials. Control of the reviewed variables is needed to achieve reliable materials in applications such as sensors, smart inks and papers, transparent flexible supports for electronics, decorative coatings and films.

Inclusion of Laponite nanoparticles in a lyotropic lamellar phase

In this work, we consider a ternary system formed by a surfactant with a lamellar phase (lecithin) that was doped with a solution of Laponite at 1% by volume. The inclusion of nanoparticles in the lamellar phase was investigated by the small-angle X-ray scattering (SAXS) technique, which revealed three types of structures according to the observed scattering pattern. The lamellar period increased linearly with hydration up to a certain limit; this type of behavior is not the same as that found for a similar system using AOT as a surfactant. In the region that corresponds to an isotropic phase, it was observed that the period corresponds to 60 Å, and in the lamellar system of pure lecithin, with the same volumetric fraction (1/φ = 0.66), the corresponding periodicity is 62 Å, indicating that the presence of Laponite nanoparticles increases the attractive interaction, reducing the lamellar period, causing the bilayer to become more rigid, that is, with less fluctuations. In the more diluted region, the periodicity reached a limit value of 64 Å, which is slightly higher than the lamellar system in the absence of Laponite particles, so there was an expansion of the lamellar phase due to the lack of consistency of Laponite nanoparticles. In the more concentrated lamellar phase (under strong confinement), it was observed that the distance between the bilayers decreased, establishing a long-range order.

How mobile phase composition and column temperature affect enantiomer elution order of liquid crystals on amylose tris(3-chloro-5-methylphenylcarbamate) as chiral selector

A comprehensive study into the effects of mobile phase composition and column temperature on enantiomer elution order was conducted with a set of chiral rod-like liquid crystalline materials. The analytes were structurally similar and comprised variances such as length of terminal alkyl chain, presence of chlorine, number of phenyl rings, and type of chiral center. Experiments were carried out in polar organic and reversed-phase modes using amylose tris(3-chloro-5-methylphenylcarbamate) immobilized on silica gel as the chiral stationary phase. For all liquid crystals, reversal of elution order of enantiomers was observed based on type of used cosolvent and/or its content in the mobile phase; for some of the liquid crystals a temperature-induced reversal was also observed. Both linear and nonlinear dependencies of natural logarithm of enantioselectivity on temperature were found. Tested mobile phases comprised pure organic solvents and binary and tertiary mixtures of acetonitrile with organic solvents and/or water. Effect of acidic/basic mobile phase additives was also tested. Effect of structure of chiral selector is briefly discussed.

An acetylcholinesterase-based biosensor for the detection of pesticides using liquid crystals confined in microcapillaries

Here, we demonstrate a capillary-sensing platform based on liquid crystals (LCs) confined in microcapillaries for simple and sensitive detection of acetylcholinesterase (AChE) and its inhibitors. LC droplets were formed through sequential injection of LCs and an aqueous solution into trichloro(octyl)silane (OTS)-treated microcapillaries. When the confined LC droplets make contact with a cationic surfactant solution, myristoylcholine chloride (Myr), the formation of a Myr monolayer at the aqueous/LC interface induces a horizontal orientation of the LCs at the interface along the microcapillary, producing an optical LC droplet texture of a four-petal shape. On the other hand, AChE can catalyze the hydrolysis of Myr into choline and myristic acid. The hydrolyzed Myr is unable to form a monolayer at the aqueous/LC interface, and therefore the confined LC droplets exhibit two bright-lined optical images when in contact with the pre-incubated mixture of Myr and AChE, corresponding to the homeotropic orientation of LCs at the interface. However, in the presence of AChE-inhibiting pesticides, such as fenobucarb and malathion, the activity of AChE is inhibited, and thus, the enzymatic hydrolysis of Myr cannot occur. As a result, the confined LC droplets present the four petal-shaped optical images when in contact with the pre-incubated mixture of Myr, AChE, and pesticides. Based on this principle, an LC-based microcapillary sensor was developed and utilized for the detection of pesticides. Using this sensing platform, fenobucarb and malathion were detected at limits of 5 pg/mL and 2.5 pg/mL, respectively. Moreover, the proposed biosensor was successfully applied to the determination of pesticides in real river water. Therefore, this LC-based microcapillary sensor is a promising platform for simple, rapid, and label-free detection of pesticides with very high sensitivity.

An ultrasensitive platform for PCB77 detection: New strategy for liquid crystal-based aptasensor fabrication

Polychlorinated biphenyls (PCBs) are considered persistent bio-accumulative toxicants which threats global food safety and environmental health. Traditional analytical techniques for detection of PCBs are time-consuming and they do not satisfy urgent need for rapid and accurate monitoring of these persistent pollutants. Biosensor technology may be promising in this respect. Here we demonstrate a novel liquid crystal (LC)-based aptasensing platform as a promising label-free and rapid biosensor for PCB77 detection. This novel molecular strategy utilize triple-helix molecular conformational switch which is mediated formation of duplex on sensing platform in presence of target. Duplex forming leads to optical change from dark to bright in a liquid crystal based aptasensor. The limit of quantification of the LC-aptasensor to PCB77 is 1.5 × 10^-5 μg/L with comparable selectivity. Besides, we also demonstrated that this system is able to detect PCB77 in tap water, environmental water and milk. This strategy has potential for label-free and portable detection of different targets without any aptamer sequence length restrictions.

The geometry of the toxicity of silver nanoparticles to freshwater mussels

The question about the influence of the geometry of silver nanoparticle (nAg) towards toxicity in aquatic organisms is largely unanswered. The purpose of this study was to examine if different geometries of nAg could initiate biophysical stress in the soft tissues of mussels. Freshwater Dreissenna bugensis mussels were exposed for 48 h at 15 °C to 10 and 50 μg/L of ionic Ag and to 3 forms of polyvinylpyrrolidone (PVP)-coated nAg of similar size: sphere, cube and prism. At the end of the exposure period, mussels were allowed to depurate overnight and the post-mitochondrial fraction of the soft tissues were analyzed for the levels of liquid crystals (LCs), changes in the activity and fractal dimensions of pyruvate kinase-lactate dehydrogenase (PK-LDH), F-actin and protein-ubiquitin (UB) levels. The data revealed that exposure to nAg forms lead to increased formation of LCs in increasing order of intensity: prismatic > cubic > spherical nAg. The activity in PK-LDH was decreased by all forms of nAg but not by ionic Ag⁺ (as with the following effects). Fractal kinetics of the PK-LDH system revealed that the nAg forms increased the spectral dimension (sD) in increasing order: spherical > cubic > prismatic nAg. A decrease in the fractal diffusion rate (fDR) with small changes in the fractal dimension (fD) was also obtained. The levels of F-actin and protein-UB were significantly affected for most forms of nAg and followed a pattern similar to LCs levels. In conclusion, the geometry of nAg could influence the formation of LCs, alter the fractal kinetics of the PK-LDH system, F-actin levels and protein damage in the soft tissues of freshwater mussels.

Graphene-assembly liquid crystalline and nanopolymer hybridization: A review on switchable device implementations

Two-dimensional graphene and its hybrid derivatives combined with liquid crystals, polymers, and nanomaterials enable the formation of hybrid nanocomposites possessing extraordinary and unique properties. Among others, these assemblies could exhibit stimulus-induced optical and electrical changes, which are essential for many new switchable device technologies. The current review deals straight forward and versatile techniques of the fabrication of exclusive graphene self-assembly of liquid crystalline polymer nanocomposite which exhibiting novel emerging equities as well as unique functionalities. Unique design makes hybrid composite matrix multidomain structures serve as both alignment and conductive layers, thus sustaining novel switchable device fabrication mechanism. Exhibited ultra thin-film nanocomposite based smart switchable devices are promising candidates for diverse applications in the field of stretchable electronics, energy storage, photodetectors, high contrast displays, and optoelectronics. Furthermore, the brand new device implementation through novel materials have the potentials of cost-effective production, large-area compatibility and scalability, and seamless heterogeneous integration.

Luliconazole loaded lyotropic liquid crystalline nanoparticles for topical delivery: QbD driven optimization, in-vitro characterization and dermatokinetic assessment

Fungal infections are an important cause of morbidity and pose a serious health concern especially in immunocompromised patients. Luliconazole (LUL) is a topical imidazole antifungal drug with a broad spectrum of activity. To overcome the limitations of conventional dosage forms, LUL loaded lyotropic liquid crystalline nanoparticles (LCNP) were formulated and characterized using a three-factor, five-level Central Composite Design of Response Surface Methodology. LUL loaded LCNP showed particle size of 181 ± 12.3 nm with an entrapment efficiency of 91.49 ± 1.61 %. The LUL-LCNP dispersion in-vitro drug release showed extended release up to 54 h. Ex-vivo skin permeation studies revealed transdermal flux value (J) of LUL-LCNP gel (7.582 μg/h/cm²) 2 folds higher compared to marketed cream (3.3706 μg/h/cm²). The retention of LUL in the stratum corneum was ∼1.5 folds higher and ∼2 folds higher in the epidermis and other deeper layers in comparison to the marketed cream. The total amount of drug penetrated (AUC_0-∞) with LCNP formulation was 4.7 folds higher in epidermis and 6.5 folds higher in dermis than marketed cream. The study's findings vouch that LCNP can be a promising and effective carrier system for the delivery of antifungal drugs with enhanced skin permeation.

Sustainable plant polyesters as substrates for optical gas sensors

The fast and non-invasive detection of odors and volatile organic compounds (VOCs) by gas sensors and electronic noses is a growing field of interest, mostly due to a large scope of potential applications. Additional drivers for the expansion of the field include the development of alternative and sustainable sensing materials. The discovery that isolated cross-linked polymeric structures of suberin spontaneously self-assemble as a film inspired us to develop new sensing composite materials consisting of suberin and a liquid crystal (LC). Due to their stimuli-responsive and optically active nature, liquid crystals are interesting probes in gas sensing. Herein, we report the isolation and the chemical characterization of two suberin types (from cork and from potato peels) resorting to analyses of gas chromatography–mass spectrometry (GC-MS), solution nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS). The collected data highlighted their compositional and structural differences. Cork suberin showed a higher proportion of longer aliphatic constituents and is more esterified than potato suberin. Accordingly, when casted it formed films with larger surface irregularities and a higher C/O ratio. When either type of suberin was combined with the liquid crystal 5CB, the ensuing hybrid materials showed distinctive morphological and sensing properties towards a set of 12 VOCs (comprising heptane, hexane, chloroform, toluene, dichlormethane, diethylether, ethyl acetate, acetonitrile, acetone, ethanol, methanol, and acetic acid). The optical responses generated by the materials are reversible and reproducible, showing stability for 3 weeks. The individual VOC-sensing responses of the two hybrid materials are discussed taking as basis the chemistry of each suberin type. A support vector machines (SVM) algorithm based on the features of the optical responses was implemented to assess the VOC identification ability of the materials, revealing that the two distinct suberin-based sensors complement each other, since they selectively identify distinct VOCs or VOC groups. It is expected that such new environmentally-friendly gas sensing materials derived from natural diversity can be combined in arrays to enlarge selectivity and sensing capacity.

Identification and sorting of particle chirality using liquid crystallinity

Particles dispersed in liquid crystals (LCs) have been shown to assemble due to the elastic interactions arising from the molecular anisotropy. Studies have shown that the alignment of the particles within LCs were strongly dependent on the surface director of LCs on particles. Different from the past studies involving particles with degenerate planar anchoring of LCs, this study shows that the azimuthal surface director can be used to control and finely tune the positioning of the particles in LCs. Specifically, polymeric particles with two flat surfaces that mediate parallel or non-parallel (chiral) anchoring were synthesized and dispersed in nematic 5CB with spatial variations in the director profile. Besides demonstration of their positioning, it was observed that the particles with same chiral handedness with the LC twist were distributed within the LC film, whereas particles with opposite handedness were repelled from the LC medium due to the elastic energy contributions. In addition, a pronounced effect of the surface anchoring of the particles were present on their orientation during non-equilibrium events such as sedimentation. Overall, the studies presented here will find potential use in sensors, separations, optics or soft robotic applications that will take advantages of chirality or chiral interactions.

Enhanced nose-to-brain delivery of tranilast using liquid crystal formulations

Intranasal administration is poised as a competent method in delivering drugs to the brain, because the nasal route has a direct link with the central nervous system bypassing the formidable blood-brain barrier. C₁₇-monoglycerol ester (MGE) and glyceryl monooleate (GMO) as liquid crystal (LC)-forming lipids possess desirable formulation characteristics as drug carriers for intranasally administered drugs. This study investigated the effect of LC formulations on the pharmacokinetics of tranilast (TL), a lipophilic model drug, and its distribution in the therapeutic target regions of the brain in rats. The anatomical biodistribution of LC formulations was monitored using micro-computed tomography tandem in vivo imaging systems. MGE and GMO effectively formed LC with suitable particle size, zeta potential, and viscosity supporting the delivery of TL to the brain. MGE and GMO LC formulations enhanced brain uptake by 10- to 12-fold and 2- to 2.4- fold, respectively, compared with TL solution. The olfactory bulb had the highest TL concentration and fluorescent signals among all the brain regions, indicating a direct nose-to-brain delivery pathway of LC formulations. LC-forming lipids, MGE and GMO, are potential biomaterials in formulations intended for intranasal administration.

Label-free liquid crystal-based biosensor for detection of dopamine using DNA aptamer as a recognition probe

We present a label-free liquid crystal-based biosensor for the detection of dopamine (DA) in aqueous solutions using dopamine-binding aptamers (DBA) as recognition elements. In this system, the dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (DMOAP) self-assembled monolayers immobilized on glass slides support the long alkyl chains that keep the liquid crystal (LC) molecules in a homeotropic orientation. Glutaraldehyde (GA) is used as a cross-linker to immobilize DBA onto the surface of glass slides. The specific binding of DA and DBA disrupts the homeotropic orientation of LCs, thereby inducing a change in the orientation from homeotropic to a random alignment. This orientation change can be converted and visualized simply as a transition from a dark optical LC image to a brighter image under a polarized optical microscope (POM), enabling the detection of DA. The developed LC-based aptasensor shows a good linear optical response towards DA in the very wide range of 1 pM-10 μM (0.19 pg/mL to 1.9 μg/mL) and has a very low detection limit of 10 pM (∼1.9 pg/mL). The biosensor also exhibited satisfactory selectivity and could be successfully applied to detect DA in human urine. The proposed LC-based aptamer sensing method offers a simple, rapid, highly sensitive and selective, and a label-free method for the analysis of DA in real clinical samples.

Nanostructure generation during milk digestion in presence of a cell culture model simulating the small intestine

HYPOTHESIS

The development of advanced oral delivery systems for bioactive compounds requires the fundamental understanding of the digestion process within the gastrointestinal tract. Towards this goal, dynamic invitro digestion models, capable of characterising the molecular as well as colloidal aspects of food, together with their biological interactions with relevant invitro cell culture models, are essential.

EXPERIMENTS

In this study, we demonstrate a novel digestion model that combines flow-through time resolved small angle X-ray scattering (SAXS) with an invitro Caco-2/HT-29 cell co-culture model that also contained a mucus layer. This set-up allows the dynamic insitu characterisation of colloidal structures and their transport across a viable intestinal cell layer during simulated digestion.

FINDINGS

An integrated online SAXS - invitro cell co-culture model was developed and applied to study the digestion of nature's own emulsion, milk. The impact of the invitro cell culture on the digestion-triggered formation and evolution of highly ordered nanostructures in milk is demonstrated. Reported is also the crucial role of the mucus layer on top of the cell layer, protecting the cells from degradation by digestive juice components such as lipase. The novel model can open unique possibilities for the dynamic investigation of colloidal structure formation during lipid digestion and their effect on the uptake of bioactive molecules by the cells.

Electrically controlled white laser emission through liquid crystal/polymer multiphases

White lasers are becoming increasingly relevant in various fields since they exhibit unprecedented properties in terms of beam brightness and intensity modulation. Here we introduce a white laser based on a polymer matrix encompassing liquid crystals and multiple organic chromophores in a multifunctional phase-separation system. The separation of the hydrophilic matrix and the hydrophobic liquid crystals leads to the formation of a complex optically active layer, featuring lasing emission tuneable from blue to red. White laser emission is found with an optical excitation threshold of approximately 12 mJ/cm2. Importantly, an external electric field can be used to control the device emission intensity. White lasers with low-voltage (≤10 V) controllable emission might pave the way for a new generation of broadband light sources for analytical, computational, and communication applications.